chore(release): v0.7.0

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Fix #30 white box: stop zeroing alpha in the watermark region on save
2026-10-18 23:37:14 +02:00 · 2026-05-30 12:35:32 -07:00 · 2026-05-30 12:27:37 -07:00 · 2026-05-30 11:44:53 -07:00 · 2026-05-29 19:49:09 -07:00 · 2026-05-29 12:28:30 -07:00
30 changed files with 1991 additions and 353 deletions
@@ -0,0 +1,46 @@
+name: Tests
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+concurrency:
+  group: tests-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: astral-sh/setup-uv@v7
+      - name: Sync dev environment
+        run: uv sync --frozen --extra dev
+      - name: Ruff lint
+        run: uv run ruff check
+      - name: Ruff format check
+        run: uv run ruff format --check
+
+  test:
+    name: test ${{ matrix.os }} py${{ matrix.python-version }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        # Cross-OS x Python-floor/recent. The default-install surface only
+        # needs the core deps plus dev tooling (no GPU extra): the model-running
+        # paths are availability-gated and skip when torch/diffusers are absent,
+        # so this matrix exercises metadata, identify, visible, and the cv2
+        # eraser on every OS without pulling the heavy ML stack.
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        python-version: ["3.10", "3.12"]
+    steps:
+      - uses: actions/checkout@v6
+      - uses: astral-sh/setup-uv@v7
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Sync dev environment
+        run: uv sync --frozen --extra dev
+      - name: Run tests
+        run: uv run pytest -q
@@ -34,6 +34,7 @@ yolov8n.pt

 # Claude Code local settings
 .claude/settings.local.json
+.claude/scheduled_tasks.lock

 # Doubao watermark calibration (local only; ship only the derived alpha-map asset).
 # Synthetic seeds + raw Doubao captures are regenerable and not committed.
@@ -5,7 +5,7 @@ You are a **principal Python engineer** maintaining a CLI tool and library for r
 ## How to run

 - `uv run remove-ai-watermarks all <image.png> -o <output.png>`
- `uv run remove-ai-watermarks visible <image.png> -o <out.png>` — visible-mark removal, CPU, no GPU. `--mark auto` (default) routes between the Gemini sparkle and the Doubao "豆包AI生成" text strip by detector confidence; `--mark gemini` / `--mark doubao` force one.
+- `uv run remove-ai-watermarks visible <image.png> -o <out.png>` — known-visible-mark removal, CPU, no GPU. **Reverse-alpha only**: every mark is removed by inverting its captured alpha map (exact pixel recovery, no inpaint). `--mark auto` (default) picks the strongest detected of the Gemini sparkle and the Doubao "豆包AI生成" text strip; `--mark gemini` / `--mark doubao` force one. For arbitrary logos/objects use `erase`.
 - `uv run remove-ai-watermarks erase <image.png> --region x,y,w,h -o <out.png>` — universal region eraser (any logo/object, any position). `--backend cv2` (default, no deps) or `--backend lama` (big-LaMa via onnxruntime, extra `lama`); `--region` is repeatable.
 - `uv run remove-ai-watermarks identify <image>` — provenance verdict (platform + watermark inventory + confidence); `--json` for machine output, `--no-visible` to skip the cv2 sparkle detector
 - `uv run remove-ai-watermarks metadata <image.png> --check` — inspect AI metadata (C2PA, EXIF, PNG chunks)
@@ -13,6 +13,7 @@ You are a **principal Python engineer** maintaining a CLI tool and library for r

 ## Test and lint

+- **CI** (`.github/workflows/test.yml`): runs on push to `main` + every PR. A `lint` job (ubuntu: `ruff check` + `ruff format --check`) plus a `test` matrix (ubuntu/macos/windows x py3.10/3.12) that does `uv sync --frozen --extra dev` then `pytest`. The matrix installs only core + dev (no `gpu` extra), so the GPU/model-running tests skip there and it exercises the metadata/identify/visible/cv2-eraser surface on all three OSes. Keep `uv.lock` valid (don't break `--frozen`) when editing `pyproject.toml`. `publish.yml` stays release-only.
 - `bash maintain.sh` — uv-outdated, uv-secure, ruff check/fix, ruff format, pyright, pytest -n auto
 - **Strict pyright is clean across `src/` (0 errors).** The cv2/torch/diffusers boundary files (`gemini_engine`, `region_eraser`, `doubao_engine`, `face_protector`, `humanizer`, `invisible_engine`, `noai/watermark_remover`, and the whole `noai/ctrlregen/` subpackage) carry a documented per-file `# pyright:` relax pragma (or, for `ctrlregen`, a `tool.pyright.executionEnvironments` entry) that turns off only the unknown-type / untyped-third-party rules — those libs ship no usable types, so strict typing there fights the ecosystem. Pure-logic files stay fully strict; `typings/piexif/__init__.pyi` is a local stub so `metadata.py`/`extractor.py` resolve piexif. Public ndarray-returning signatures on the relaxed engines are still annotated `NDArray[Any]` so strict consumers (`cli.py`) stay clean. When touching a relaxed file, prefer fixing real issues over widening the pragma; keep the pragma scoped to genuinely-untyped boundaries. (`uv-secure` is clean since idna was bumped 3.11 -> 3.16, fixing GHSA-65pc-fj4g-8rjx.)
 - **Full-project `uv run pyright` (no path) OOMs/crashes node on this ML-heavy repo** (emits a `libnode` stack frame, no summary) — a known environment limit, not a code error. Gate with `uv run --extra dev --extra gpu pyright src/` (completes, authoritative) or scope to changed files; also run `uv run ruff check` and `uv run pytest` directly.
@@ -31,29 +32,38 @@ You are a **principal Python engineer** maintaining a CLI tool and library for r

 - `noai/c2pa.py` — PNG chunk parser; use `extract_c2pa_chunk(path)` to get raw caBX payload, `has_c2pa_metadata(path)` to detect. Do not reimplement chunk parsing. `extract_c2pa_info(path)` sets `synthid_watermark`/`synthid_vendors` when the manifest is signed by a SynthID-using vendor, and `soft_binding`/`soft_binding_vendors` when a `c2pa.soft-binding` `alg` names a forensic-watermark vendor (`soft_binding_vendors_in(buffer)` is the shared byte-scan, used by both the PNG parser and the non-PNG binary path).
 - `noai/constants.py` — PNG_SIGNATURE, C2PA_CHUNK_TYPE, C2PA_SIGNATURES, C2PA_ISSUERS, `SYNTHID_C2PA_ISSUERS` (issuers that pair SynthID with C2PA: Google, OpenAI), and `C2PA_SOFT_BINDINGS` (soft-binding `alg` prefix → forensic-watermark vendor: Adobe TrustMark, Digimarc, Imatag, Steg.AI, Microsoft, ...). Add a new issuer/binding here, not inline.
- `metadata.py` — `scan_head(path, size=1MB)` is the shared input for every C2PA/AIGC/IPTC byte scan: first `size` bytes plus, for ISOBMFF, the late provenance-box payloads from `isobmff.scan_c2pa_region` (catches a manifest after a large `mdat`); behavior-neutral (`f.read(size)`) for non-ISOBMFF. Use it instead of `open().read(1MB)` for any new marker scan. `synthid_source(path)` returns the vendor name(s) if the C2PA manifest implies a SynthID pixel watermark, else None. Format-agnostic: PNG via the caBX parser, JPEG/WebP/AVIF/HEIF/JXL via a binary scan (C2PA marker + SynthID issuer + AI-source marker). `get_ai_metadata` surfaces the verdict, and `metadata --check` prints it as a callout. Both `get_ai_metadata` and `has_ai_metadata` guard the PIL open with `except Exception` (HEIC/unknown formats raise non-OSError) and fall through to the binary scan. `xai_signature(path)` detects xAI/Grok's EXIF-only scheme (`ImageDescription` = `Signature: <base64>` + UUID `Artist`); it feeds `has_ai_metadata`, `get_ai_metadata` (key `xai_signature`), and `identify`. `iptc_ai_system(path)` detects the IPTC Photo Metadata 2025.1 AI-disclosure XMP properties (`IPTC_AI_FIELD_MARKERS` = `AISystemUsed`/`AISystemVersionUsed`/`AIPromptInformation`/`AIPromptWriterName`) and returns the `AISystemUsed` generator name (or `"fields present"`). `remove_ai_metadata` routes **ISOBMFF video** (`.mp4`/`.mov`/`.m4v`) through the same `isobmff.strip_c2pa_boxes` as AVIF/HEIF (MP4 is ISOBMFF), and `_scrub_ai_exif` removes the xAI signature + AI-generator EXIF tags on JPEG output.
- `identify.py` — `identify(path)` aggregates every locally-readable signal (C2PA issuer→platform, C2PA soft-binding forensic-watermark vendor, IPTC "Made with AI" + IPTC 2025.1 `AISystemUsed`, embedded SD/ComfyUI params, SynthID proxy, xAI/Grok EXIF signature via `metadata.xai_signature`, the China TC260 AIGC label via `metadata.aigc_label`, the HuggingFace `hf-job-id` job marker via `metadata.huggingface_job`, visible Gemini sparkle, open invisible watermark, Adobe TrustMark via `trustmark_detector`) into one `ProvenanceReport`. `is_ai_generated` is True or None (never asserted False — stripped metadata is not proof of clean origin). The `hf_job` and visible-sparkle signals are **medium** confidence: each lifts an otherwise-Unknown verdict to a tentative AI (`hf_only` / `visible_only`, parallel branches) but is excluded from the high-confidence `ai_from_metadata` set, so neither overrides a hard metadata signal. Visible-sparkle is promoted only at confidence ≥ `_SPARKLE_THRESHOLD` (0.5; corpus-tuned to separate Gemini sparkles ≥0.56 from non-sparkle ≤0.49). The cv2 dependency lives in `gemini_engine.detect_sparkle_confidence`, not here. **C2PA platform attribution is device-token-first, issuer-scan fallback** (`_device_platform` scans manifest bytes for `_DEVICE_C2PA_PLATFORM` tokens, then `_attribute_platform`/`_ISSUER_PLATFORM`). **Why, verified on real signed files 2026-05-26:** the old issuer-only byte-scan matched ANY issuer substring anywhere, so multi-entity manifests mis-attributed -- Leica→"Truepic" (a signing authority in the trust chain), Nikon→"Adobe Firefly" (XMP-toolkit "Adobe" + the sample's "Adobe_MAX" name), Pixel→"Google (Gemini)" ("Google LLC" cert org), Truepic→"Google". A distinctive device token wins instead. **Token distinctiveness is load-bearing:** bare `b"Truepic"` mis-fires (it appears in unrelated trust chains -- it mis-attributed the OpenAI `chatgpt-1.png` fixture), so the token is the specific `b"Truepic_Lens"` from the Lens SDK claim generator; likewise `b"Pixel Camera"` (cert CN) not bare `b"Pixel"`. `_DEVICE_C2PA_PLATFORM` lists ONLY tokens **verified against a real C2PA file**: Leica (`lc_c2pa`/`Leica Camera`), Nikon (`NIKON`), Pixel (`Pixel Camera` -- from a real Pixel 10 Pro file attached to c2pa-rs issue #1609/#1554), Sony (`sony.sig`/`sony.cert` -- Sony's own C2PA assertion namespace, verified on a real Sony PXW-Z300 file; NOT bare "Sony" which is a common EXIF Make), Truepic (`Truepic_Lens`). Canon/Samsung/Bria have **no public direct-download C2PA sample** (checked exhaustively: GitHub issue/PR attachments, contentcredentials gallery, HF datasets -- all upload-to-verify or token-gated; Canon's only public file was a self-signed hobbyist CR3, not factory), so they stay unmapped until a real file is captured (same fixture discipline as Grok/Doubao). The Sony sample is video (MP4) -- our ISOBMFF C2PA path detects it; Sony Alpha stills likely share the `sony.*` namespace but are not separately verified. Camera C2PA marks capture authenticity, not AI (Pixel carries `computationalCapture`, not `trainedAlgorithmicMedia`), so these never set `is_ai` -- that stays driven by digital-source-type. `c2pa.cbor_text_after` (now public) is best-effort for the `generator` detail string only and can be None when the manifest keys it `claim_generator_info` (Pixel). **Issuer→generator mapping is `is_ai`-gated** (`_attribute_platform(issuers, is_ai=c2pa_is_ai)`): a specific AI-generator platform is named only when the digital-source-type is `trainedAlgorithmicMedia`; on a non-AI source an issuer substring is treated as incidental (an "Adobe XMP" toolkit string in an *unmapped* Canon/Sony capture would otherwise mislabel it "Adobe Firefly"), so it degrades to the neutral "C2PA signer: X" label. Real Firefly/OpenAI/Google output carries the AI source-type, so it is unaffected (verified: chatgpt-1.png→OpenAI, firefly-1.png→Adobe Firefly still attribute). `_attribute_platform` defaults `is_ai=True` so the mapping stays unit-testable in isolation. Add device tokens to `_DEVICE_C2PA_PLATFORM`, generator/issuer platforms to `_ISSUER_PLATFORM`, not inline. For non-PNG containers (JPEG/WebP/AVIF/HEIF/JXL) the caBX parser returns nothing, so issuer (`_issuers_in`) and generator (`_ai_tools_in`, reusing `C2PA_AI_TOOLS`) are recovered by binary-scanning the first MB. EXIF `Software` / `Make` / `Artist` / `ImageDescription` and XMP `CreatorTool` generator tags are read by `metadata.exif_generator` (PIL+piexif for any format PIL opens incl. AVIF, plus a container-agnostic XMP raw-byte scan that also covers HEIF/JXL), matched against `AI_GENERATOR_TOKENS` so ordinary editors (plain "Adobe Photoshop") and real-camera `Make` ("Apple"/"Canon") are not flagged. **Ideogram tags its output with EXIF `Make="Ideogram AI"`** (verified on a real download 2026-05-24) — that's why `Make` is read. **Integrity-clash detection** (`_integrity_clashes`, surfaced as `ProvenanceReport.integrLine truncated
+- `metadata.py` — `scan_head(path, size=1MB)` is the shared input for every C2PA/AIGC/IPTC byte scan: first `size` bytes plus the payloads of any provenance metadata found beyond that window — for ISOBMFF, the late provenance boxes from `isobmff.scan_c2pa_region` (catches a manifest after a large `mdat`); for **PNG**, the late `tEXt`/`iTXt`/`zTXt`/`eXIf`/`iCCP` chunks from `_png_late_metadata` (catches an XMP/EXIF packet appended after a large `IDAT`, e.g. a TC260 AIGC label at ~2.7 MB). Behavior-neutral (`f.read(size)`) for non-ISOBMFF inputs and for any file that fits within `size`. Use it instead of `open().read(1MB)` for any new marker scan. `synthid_source(path)` returns the vendor name(s) if the C2PA manifest implies a SynthID pixel watermark, else None. Format-agnostic: PNG via the caBX parser, JPEG/WebP/AVIF/HEIF/JXL via a binary scan (C2PA marker + SynthID issuer + AI-source marker). `get_ai_metadata` surfaces the verdict, and `metadata --check` prints it as a callout. Both `get_ai_metadata` and `has_ai_metadata` guard the PIL open with `except Exception` (HEIC/unknown formats raise non-OSError) and fall through to the binary scan. `xai_signature(path)` detects xAI/Grok's EXIF-only scheme (`ImageDescription` = `Signature: <base64>` + UUID `Artist`); it feeds `has_ai_metadata`, `get_ai_metadata` (key `xai_signature`), and `identify`. `iptc_ai_system(path)` detects the IPTC Photo Metadata 2025.1 AI-disclosure XMP properties (`IPTC_AI_FIELD_MARKERS` = `AISystemUsed`/`AISystemVersionUsed`/`AIPromptInformation`/`AIPromptWriterName`) and returns the `AISystemUsed` generator name (or `"fields present"`). `remove_ai_metadata` routes **ISOBMFF video** (`.mp4`/`.mov`/`.m4v`) through the same `isobmff.strip_c2pa_boxes` as AVIF/HEIF (MP4 is ISOBMFF), and `_scrub_ai_exif` removes the xAI signature + AI-generator EXIF tags on JPEG output.
+- `identify.py` — `identify(path)` aggregates every locally-readable signal (C2PA issuer→platform, C2PA soft-binding forensic-watermark vendor, IPTC "Made with AI" + IPTC 2025.1 `AISystemUsed`, embedded SD/ComfyUI params, SynthID proxy, xAI/Grok EXIF signature via `metadata.xai_signature`, the China TC260 AIGC label via `metadata.aigc_label`, the HuggingFace `hf-job-id` job marker via `metadata.huggingface_job`, the Samsung Galaxy AI editing marker via `metadata.samsung_genai`, visible Gemini sparkle, open invisible watermark, Adobe TrustMark via `trustmark_detector`) into one `ProvenanceReport`. `is_ai_generated` is True or None (never asserted False — stripped metadata is not proof of clean origin). The `hf_job`, visible-sparkle, and Samsung `samsung_genai` signals are **medium** confidence: each lifts an otherwise-Unknown verdict to a tentative AI (`hf_only` / `visible_only` / `samsung_only`, parallel branches) but is excluded from the high-confidence `ai_from_metadata` set, so none overrides a hard metadata signal. Visible-sparkle is promoted only at confidence ≥ `_SPARKLE_THRESHOLD` (0.5; corpus-tuned to separate Gemini sparkles ≥0.56 from non-sparkle ≤0.49). The cv2 dependency lives in `gemini_engine.detect_sparkle_confidence`, not here. **C2PA platform attribution is device-token-first, issuer-scan fallback** (`_device_platform` scans manifest bytes for `_DEVICE_C2PA_PLATFORM` tokens, then `_attribute_platform`/`_ISSUER_PLATFORM`). **Why, verified on real signed files 2026-05-26:** the old issuer-only byte-scan matched ANY issuer substring anywhere, so multi-entity manifests mis-attributed -- Leica→"Truepic" (a signing authority in the trust chain), Nikon→"Adobe Firefly" (XMP-toolkit "Adobe" + the sample's "Adobe_MAX" name), Pixel→"Google (Gemini)" ("Google LLC" cert org), Truepic→"Google". A distinctive device token wins instead. **Token distinctiveness is load-bearing:** bare `b"Truepic"` mis-fires (it appears in unrelated trust chains -- it mis-attributed the OpenAI `chatgpt-1.png` fixture), so the token is the specific `b"Truepic_Lens"` from the Lens SDK claim generator; likewise `b"Pixel Camera"` (cert CN) not bare `b"Pixel"`. `_DEVICE_C2PA_PLATFORM` lists ONLY tokens **verified against a real C2PA file**: Leica (`lc_c2pa`/`Leica Camera`), Nikon (`NIKON`), Pixel (`Pixel Camera` -- from a real Pixel 10 Pro file attached to c2pa-rs issue #1609/#1554), Sony (`sony.sig`/`sony.cert` -- Sony's own C2PA assertion namespace, verified on a real Sony PXW-Z300 file; NOT bare "Sony" which is a common EXIF Make), Truepic (`Truepic_Lens`). Canon/Bria have **no public direct-download C2PA sample** (checked exhaustively: GitHub issue/PR attachments, contentcredentials gallery, HF datasets -- all upload-to-verify or token-gated; Canon's only public file was a self-signed hobbyist CR3, not factory), so they stay unmapped until a real file is captured (same fixture discipline as Grok/Doubao). The Sony sample is video (MP4) -- our ISOBMFF C2PA path detects it; Sony Alpha stills likely share the `sony.*` namespace but are not separately verified. **Samsung Galaxy + ASUS Gallery live in a separate `_SIGNER_C2PA_PLATFORM` (scanned after `_device_platform`, before the issuer fallback), NOT in `_DEVICE_C2PA_PLATFORM`** — verified on real signed files 2026-05-29. Reason: a Galaxy phone stamps BOTH its device cert AND a `trainedAlgorithmicMedia`/genAIType AI marker on a Generative-Edit image, so treating it as a "genuine camera capture" would false-fire integrity-clash rule 2 on every Galaxy AI edit. The signer tokens (`b"Samsung Galaxy"` cert org — distinct from the EXIF `SM-xxxx` model string on ordinary Samsung photos; `b"com.asus.gallery"` claim generator) only resolve the platform label; the AI verdict still comes from the source-type / genAIType. ASUS Gallery is a C2PA-signed edit with no AI marker, so it attributes the platform without asserting `is_ai`. **Samsung's `genAIType` (in the proprietary `PhotoEditor_Re_Edit_Data` JSON) is an undocumented Galaxy-AI editing marker** (`metadata.samsung_genai`, gated on the `PhotoEditor_Re_Edit_Data` container; non-zero value = AI tool used, values {1,5} observed): medium-confidence because the field has no public spec (verified 2026-05-29: absent from C2PA spec + Samsung docs), but it co-occurred with `trainedAlgorithmicMedia` in 3/3 verified files that record a source-type and was the SOLE AI marker on a Galaxy S24 file that omits the source type. Camera C2PA marks capture authenticity, not AI (Pixel carries `computationalCapture`, not `trainedAlgorithmicMedia`), so these never set `is_ai` -- that stays driven by digital-source-type. `c2pa.cbor_text_after` (now public) is best-effort for the `generator` detail string only and can be None when the manifest keys it `claim_generator_info` (Pixel). **Issuer→generator mapping is `is_ai`-gated** (`_attribute_platform(issuers, is_ai=c2pa_is_ai)`): a specific AI-generator platform is named only when the Line truncated
+- `watermark_registry.py` — **single catalog of known visible watermarks**, the unified "find known marks in their usual places, recognize, remove" entry. **Reverse-alpha only by policy**: a mark is listed only once a real alpha map has been captured for it, and removal inverts that map (`original = (wm - a*logo)/(1-a)`, exact recovery) — no inpaint/heuristic removal here (arbitrary-region inpainting lives in `region_eraser`/`erase`). Each `KnownMark` ties a key to {usual `location`, `in_auto` flag, `recovery` (="reverse-alpha"), a `detect` adapter → uniform `MarkDetection`, a `remove` adapter}. Entries today: `gemini` (bottom-right sparkle) and `doubao` (bottom-right "豆包AI生成"). `detect_marks` scans all; `best_auto_mark` picks the highest-confidence detection. **Cross-engine confidences aren't directly comparable**, so the gemini adapter applies the corpus-validated 0.5 sparkle threshold (`_GEMINI_AUTO_MIN_CONF`) for its `detected` flag — otherwise the gemini engine's loose internal threshold weakly fires (~0.36) on the Doubao text and hijacks `auto`. `cli.cmd_visible` is registry-driven: `--mark auto` → `best_auto_mark`, `--mark <key>` → that mark; `--mark` choices come from `mark_keys()`. `_doubao_remove` applies reverse-alpha only when the mark is detected AND `reverse_alpha_available` (resolution in the alpha band); outside that, removal is **skipped** (not inpainted). Add a new visible mark = one `KnownMark` entry + its engine (with a captured alpha map); do not re-add per-mark `if` branches in the CLI. **Alpha-on-save policy (issue #30):** `cli._write_bgr_with_alpha` rejoins the input's alpha plane **unchanged** — it must NOT zero alpha in the watermark bbox. Reverse-alpha (and `erase` inpaint) recover real pixels there, so zeroing alpha punched a transparent hole that renders as a solid **white box** on any non-transparent viewer (Gemini app exports are opaque RGBA, so every user hit it; regression-guarded by `test_visible_keeps_alpha_opaque_in_watermark_region`). The registry `remove()` still returns its region (used for `inpaint_residual` positioning), but the CLI no longer uses it to clear alpha.
 - `gemini_engine.py` — visible Gemini-sparkle remover/detector (cv2/numpy, no GPU). `detect_sparkle_confidence(path)` is the file-level entry point used by `identify.py`.
- `doubao_engine.py` — visible Doubao "豆包AI生成" remover/detector (cv2/numpy, no GPU). `DoubaoEngine.locate` anchors a bottom-right box by **geometry** (mark scales with image WIDTH, fractions in module constants; no bundled template), `extract_mask` pulls the light low-saturation glyphs with a **polarity-aware white top-hat** (brighter-than-blurred-local-bg, so white-paper documents are left untouched instead of smeared), `detect` thresholds glyph coverage (`DETECT_MIN_COVERAGE` 0.16 separates real marks ≥0.20 from corner noise, which stays ≤0.06 on large images but can spike to ~0.15 on tiny ones), `remove_watermark` inpaints (cv2 Telea/NS) and **bails when coverage > `MAX_INPAINT_COVERAGE` 0.50** (dense-text background → would smear). Wired into `visible --mark` via `cli._run_doubao_if_selected`. **Logo is near-white (~253), not the gray some third-party tools assume.** Best on photo/illustration backgrounds; high-contrast edges leave faint residue (cv2-inpaint limit). Clean per-pixel reverse-alpha (Gemini-style) is the future upgrade but needs a captured/distilled alpha map — see below.
+- `doubao_engine.py` — visible Doubao "豆包AI生成" remover/detector (cv2/numpy, no GPU), **reverse-alpha only**. `DoubaoEngine.locate` anchors a bottom-right box by **geometry** (mark scales with image WIDTH), `extract_mask` pulls the light low-saturation glyphs (the detection candidate). `detect` is **reverse-alpha-consistent**: it matches the bundled alpha glyph silhouette (`assets/doubao_alpha.png`, the exact shape we invert) against the candidate via zero-mean normalized correlation (`_template_match_score`, cv2 `TM_CCOEFF_NORMED`), gated at `DETECT_NCC_THRESHOLD` 0.4 over a small `DETECT_MIN_COVERAGE` floor. Keying on glyph SHAPE (not coverage/structure heuristics) fixed #23: corpus FP fell to 7/1243 (0.6%); old coverage-only fired on ~28%. **Removal is exact reverse-alpha** (`remove_watermark_reverse_alpha`): `original = (wm - a*logo)/(1-a)` from the bundled alpha map + `_ALPHA_LOGO_BGR` (near-white ~253) + `_ALPHA_*_FRAC` geometry. The alpha map + logo were **solved from real black+gray Doubao captures** (`data/doubao_capture/captures/`, gitignored): on black `captured = a*logo`, the black/gray pair solves `a` per-pixel without assuming the logo colour (white capture cross-validates: mark → flat fill). The single captured alpha map (at width 2048) **generalizes to any resolution**: at (near) the captured width (`_ALPHA_NATIVE_BAND` of `_ALPHA_NATIVE_WIDTH`) `_fixed_alpha_map` places it by exact width-relative geometry (pixel-exact recovery, ~0.9 mean error — the whole point of reverse-alpha); off that width it **tries BOTH placements -- fixed geometry AND `_aligned_alpha_map`'s `TM_CCOEFF_NORMED` scale+position search (`_ALPHA_ALIGN_SEARCH`) -- and keeps whichever leaves the least residual mark** (re-`detect` confidence on the bare reverse-alpha). On a faint/busy-background mark the NCC peak wanders a few px and geometry wins; on a clear mark alignment wins -- no magic threshold, it just picks the better removal. Verified **56/56 real detected-Doubao removed clean across all corpus resolutions** (2048 fixed 27/27, 1773 22/22, plus 1185/1187/1535/1672); a single fixed-vs-aligned choice left 2/56 busy-background residuals, try-both fixed them. `reverse_alpha_available` is just "asset present"; the registry still gates removal on `detect` so a clean corner is never touched. **Residual inpaint is off-native-only:** at the captured width the fixed-geometry recovery is exact, so it is returned untouched -- inpainting over exactly-recovered interior pixels only swaps them for a cv2 hallucination (measured worse, native textured-bg error vs true bg **1.6 reverse-alpha-only vs 2.6 with the old always-on full-footprint inpaint**; regression-guarded by `test_native_returns_exact_reverse_alpha_no_inpaint`). Off-native the NCC alignment is only sub-pixel-approximate, so the interior is no longer exact and a residual inpaint over the glyph footprint cleans the seam (costs nothing there and reliably clears the mark). The shipped third-party `_refs/zhengsuanfa_doubao_alpha_120x20.png` is NOT a usable alpha (≈0.85 everywhere → blacks out on inversion; wrong resolution/version), verified 2026-05-29. There is no inpaint-based removal here (removed 2026-05-29; arbitrary-region inpainting is `region_eraser`/`erase`).
 - `region_eraser.py` — universal region eraser (`erase` CLI). `erase(image, boxes=|mask=, backend=)`: `boxes_to_mask` → `cv2.inpaint` (`cv2` backend, default, no deps) or big-LaMa via onnxruntime (`lama` backend, extra `lama`, `Carve/LaMa-ONNX` Apache-2.0 model downloaded on first use, never bundled). `erase_lama` crops a padded region around the mask, runs LaMa at its fixed 512² input, pastes only masked pixels back (untouched areas stay pixel-exact). Lazy `_get_lama_session` singleton; `lama_available()` guards the optional import. **LaMa-ONNX costs ~3.5-4 GB peak RAM and ~5-6 s/call on CPU** (FFC working set, not arena — `enable_cpu_mem_arena=False` does not help), so it does NOT fit a minimal droplet; the cv2 backend (tens of MB, ~30 ms) does. LaMa quality at low RAM = serverless/GPU, mirroring how raiw.cc offloads SDXL to fal.
 - `invisible_watermark.py` — `detect_invisible_watermark(path)` decodes the OPEN DWT-DCT watermarks (public decoder, no key) embedded by Stable Diffusion / SDXL / FLUX via the `imwatermark` library. Known fixed patterns (verified against upstream source) live in `_BITS_48` (SDXL 48-bit, FLUX.2 48-bit) and `_SD1_STRING` ("StableDiffusionV1", SD 1.x/2.x). Optional dep (extra `detect`); returns None when absent. The `detect` extra pulls **torch** transitively (invisible-watermark declares torch a hard dep, and `WatermarkDecoder` eagerly imports `rivaGan` -> `torch` at import time), so detection needs torch present even though dwtDct runs CPU-only on cv2/numpy/pywavelets — no GPU and no separate `gpu` extra required. **Unlike SynthID this is locally detectable**, but the watermark is fragile (does not survive JPEG re-encode/resize — verified gone after JPEG q90), so it confirms origin only on pristine files. Add new known patterns here. The file carries a top-of-module pyright pragma because imwatermark/cv2 ship no type stubs.
- `trustmark_detector.py` — `detect_trustmark(path)` decodes the OPEN, keyless **Adobe TrustMark** watermark (the soft binding behind Adobe Durable Content Credentials, `alg` `com.adobe.trustmark.P`) via the optional `trustmark` package (extra `trustmark`; pulls torch, downloads model weights on first use). Mirrors `invisible_watermark.py` (lazy singleton, top-of-module pyright pragma, returns None when absent). It detects *provenance*, not AI origin as such (TrustMark also marks human-authored content), so `identify` lists it as a watermark without setting `is_ai_generated`. Other soft-binding vendors (Digimarc/Imatag/Steg.AI/...) have no public decoder — they are only *named* via the `C2PA_SOFT_BINDINGS` scan, not decoded.
- `text_protector.py` — text-region protection for the `invisible` SDXL img2img pass (issue #21: CJK/small text deforms at watermark-removal strengths). `is_available()` gates on `cv2.dnn.TextDetectionModel_DB`; `TextProtector.detect_text_boxes(bgr)` runs the **PP-OCRv3 CN** ONNX detector (~2.4 MB, Apache-2.0, opencv_zoo, CJK-native, returns rotated quad polygons) — downloaded+cached to `~/.cache/remove-ai-watermarks` on first use via atomic temp-rename, never bundled, **no torch (cv2.dnn only)**. `build_change_map(boxes, h, w, preserve=0.9, feather=15)` paints a Differential-Diffusion change map. **Polarity (verified empirically):** white(1.0)=PRESERVE original pixels, black(0.0)=MAX change; map is black bg + `preserve` inside text polygons, Gaussian-feathered edges, clipped to [0,1]. `preserve` stays below a hard 1.0 freeze by default so text still scrubs lightly (SynthID survives cropping). Wired into `watermark_remover._run_differential` via the community `pipeline_stable_diffusion_xl_differential_img2img` (loaded with `custom_revision="0.38.0"` — HF resolves the **PyPI** version string, not the `v0.38.0` git tag); gated to the SDXL `DEFAULT_MODEL_ID` only (`_can_protect_text`), falls back to plain img2img otherwise. **Autonomous by default** (`protect_text=True` in `invisible_engine`/`watermark_remover`, mirroring `protect_faces`): the detector runs per image and `_run_differential` falls back to plain img2img when **no boxes** are found, so text-free inputs pay only the cheap cv2 detection (no differential-pipeline load). CLI exposes a single off-switch `--no-protect-text` on `invisible`/`all` (passed as `protect_text=not no_protect_text`); the unavailable-model case logs at debug, not warning, since it is now the default path. The diff pipeline upcasts the VAE to fp32 internally, so do **not** add `upcast_vae()`/`enable_attention_slicing` (both produced NaN/black on fp16 MPS). `build_change_map` is unit-tested without any model download (`tests/test_text_protector.py`).
+- `trustmark_detector.py` — `detect_trustmark(path)` decodes the OPEN, keyless **Adobe TrustMark** watermark (the soft binding behind Adobe Durable Content Credentials, `alg` `com.adobe.trustmark.P`) via the optional `trustmark` package (extra `trustmark`; pulls torch, downloads model weights on first use). Mirrors `invisible_watermark.py` (lazy singleton, top-of-module pyright pragma, returns None when absent). It detects *provenance*, not AI origin as such (TrustMark also marks human-authored content), so `identify` lists it as a watermark without setting `is_ai_generated`. Other soft-binding vendors (Digimarc/Imatag/Steg.AI/...) have no public decoder — they are only *named* via the `C2PA_SOFT_BINDINGS` scan, not decoded. **False-positive gate (added 2026-05-29):** TrustMark's `wm_present` is a BCH error-correction validity flag that spuriously validates on a content-correlated fraction of un-watermarked images — AI-generated textures trip it far more than camera photos (verified 2026-05-29 on real files: it fires on Gemini/OpenAI/Doubao output that *cannot* carry Adobe's watermark, with a random-bytes decoded secret, while signal-free camera photos did not trip it). A genuine TrustMark is a *durable* soft binding engineered to survive re-encoding, so `detect_trustmark` re-decodes after a mild JPEG round-trip (`_survives_reencode`, `_REENCODE_QUALITY` 95) and requires the same schema both times; every observed false positive collapsed (none survived even q95), so the gate is the durability property the watermark guarantees. The second decode runs only on the rare initial hit, so the cost is negligible. Do NOT remove the gate to "catch more" — a lone TrustMark hit without it is almost always content noise.
+- `text_protector.py` — text-region protection for the `invisible` SDXL img2img pass (issue #21: CJK/small text deforms at watermark-removal strengths). `is_available()` gates on `cv2.dnn.TextDetectionModel_DB`; `TextProtector.detect_text_boxes(bgr)` runs the **PP-OCRv3 DB** ONNX detector (~2.4 MB, Apache-2.0, opencv_zoo, returns rotated quad polygons) — downloaded+cached to `~/.cache/remove-ai-watermarks` on first use via atomic temp-rename, never bundled, **no torch (cv2.dnn only)**. **Detection is script-agnostic** (DB segments text *regions*, not characters), so Latin / Cyrillic / CJK / Hangul / Arabic / digits all detect identically — language was never the recall lever, **resolution was**. `_detection_input_size(h, w)` (pure, unit-tested) detects at the **native long side capped at `_DET_MAX_LONG_SIDE` (1536), never upscaled**: the old fixed 736 downscaled large canvases so small text fell below the detector and was missed (issue #14, e.g. ~16 px text on a 2048 image). `scripts/text_detection_benchmark.py` measures recall across scripts × sizes × canvas: the cap fix lifts overall hit-rate 0.91 → 1.00 (worst cell 2048/16 px: 0.06 → 1.00) at ~100 ms CPU. Very large canvases with tiny text may still need tiling (documented limit, not built). `build_change_map(boxes, h, w, preserve=0.9, feather=15)` paints a Differential-Diffusion change map. **Polarity (verified empirically):** white(1.0)=PRESERVE original pixels, black(0.0)=MAX change; map is black bg + `preserve` inside text polygons, Gaussian-feathered edges, clipped to [0,1]. `preserve` stays below a hard 1.0 freeze by default so text still scrubs lightly (SynthID survives cropping). Wired into `watermark_remover._run_differential` via the community `pipeline_stable_diffusion_xl_differential_img2img` (loaded with `custom_revision="0.38.0"` — HF resolves the **PyPI** version string, not the `v0.38.0` git tag); gated to the SDXL `DEFAULT_MODEL_ID` only (`_can_protect_text`), falls back to plain img2img otherwise. **Autonomous by default** (`protect_text=True` in `invisible_engine`/`watermark_remover`, mirroring `protect_faces`): the detector runs per image and `_run_differential` falls back to plain img2img when **no boxes** are found, so text-free inputs pay only the cheap cv2 detection (no differential-pipeline load). CLI exposes a single off-switch `--no-protect-text` on `invisible`/`all` (passed as `protect_text=not no_protect_text`); the unavailable-model case logs at debug, not warning, since it is now the default path. The diff pipeline upcasts the VAE to fp32 internally, so do **not** add `upcast_vae()`/`enable_attention_slicing` (both produced NaN/black on fp16 MPS). `build_change_map` is unit-tested without any model download (`tests/test_text_protector.py`).
 - `face_protector.py` — YOLO detect + soft-blend pattern; mirror this for any "protect region during diffusion" features
 - `image_io.py` — Unicode-safe cv2 IO (issue #17). `imread(path, flags=None)` / `imwrite(path, img)` wrap `np.fromfile`+`cv2.imdecode` / `cv2.imencode`+`tofile` so non-ASCII paths work on Windows -- bare `cv2.imread`/`cv2.imwrite` use the platform ANSI code-page API there and fail (empty decode + `can't open/read file`) on Chinese/Cyrillic/accented filenames. `imread` keeps `cv2.imread` semantics (defaults to `IMREAD_COLOR`, returns `None` on missing/empty/undecodable). **Every cv2 file read/write in the package routes through here; do not call `cv2.imread`/`cv2.imwrite` directly.** macOS/Linux already accept UTF-8 paths, so it is behavior-neutral there (the bug only reproduces on Windows). cv2/numpy are imported lazily inside the functions, so the module is cheap to import in a bare env.

-### Doubao clean-reverse-alpha distillation (researched 2026-05-26, NOT yet shipped)
+### Doubao clean-reverse-alpha distillation (re-investigated 2026-05-29)

-Plan to get Gemini-style pixel-accurate reverse-alpha for Doubao at cv2 cost (so it runs on a minimal CPU droplet): use LaMa **offline** to reconstruct the clean background `O`, then per-pixel solve `I=(1-α)O+αL` for the alpha map + logo colour (this is Google's CVPR-2017 multi-image idea, with LaMa standing in for the multi-image optimisation). Validated in principle (glyph error drops as alignment improves) but **blocked on data**, confirmed empirically over 6 attempts: a clean canonical alpha map needs **several PRISTINE images at ONE resolution** with varied backgrounds. The findable public Doubao images (ayaya, Tools_CleanMark, ours) are all different resolutions AND lossy (jpg/webp), and Doubao's mark position drifts ~±50 px even at the same resolution, so cross-image registration (ECC / phase-correlation) fails (1/11 templates aligned) — error floor ~64/255 on glyph pixels, not shippable. To finish: ~5-8 pristine same-resolution Doubao originals → per-image α via LaMa → align the clean α templates → median → ship the tiny map + an NCC localiser (Doubao's mark drifts, so runtime needs the same locate-then-reverse-alpha the Gemini engine already does). Don't retry on lossy/mixed-resolution scraped images — proven insufficient.
+**RESOLVED 2026-05-29: black+gray Doubao captures were obtained and the exact reverse-alpha is built** (`doubao_engine.remove_watermark_reverse_alpha`, `assets/doubao_alpha.png`; see the `doubao_engine.py` bullet above). The captures (`data/doubao_capture/captures/`, gitignored) confirmed the alpha-composite model: on black `captured = a*logo`, the black/gray pair solves `a` per-pixel (`a_max≈0.65`, logo near-white), and the white capture cross-validates. A single 2048 capture suffices: sub-pixel NCC alignment (`_aligned_alpha_map`) registers the alpha glyph to the real mark, so it works at any resolution (verified on the 1773×2364 3:4 corpus size), not just 2048. The notes below (the failed content-image distillation) are retained as the record of why captures were necessary.
+
+**Conclusion (historical): pure reverse-alpha distilled from content images does NOT work, and the blocker is the WRONG kind of data, not too little of it.** The earlier framing ("need ~5-8 PRISTINE same-resolution originals") is obsolete -- `data/spaces/originals/` holds plenty. Curate them with `DoubaoEngine.detect` + an NCC filter against a clean glyph template, keeping only marks at offset ≈ (0,0): that yields e.g. **15 pixel-aligned 2048² marks** (sub-pixel drift, not the ±50 px the old lossy/mixed-res scrapes had), plus 1086x1448 / 1792x2400 clusters. With those, LaMa-clean `O` + weighted-LS (and per-pixel I-on-O regression) for `α` (+ logo colour) was tried end-to-end and **still leaves a persistent ghost outline.**
+
+Diagnosed why, empirically (cached stacks, `/tmp/doubao_distill`): (1) the mark is a clean white overlay with **no dark halo** -- over glyph pixels ~54% are brighter than the clean bg, only ~4% darker -- so the white-logo model `I=(1-α)O+α·255` is correct; (2) but content backgrounds are almost never dark *under* the mark (median darkest available bg over glyph pixels = **58/255**; only ~13% of mark pixels are ever observed on a bg < 40), so on bright backgrounds the equation is ill-conditioned and `α` is unidentifiable; (3) LaMa's `O` is a plausible **hallucination**, not the true pre-mark background, which compounds the error, and per-pixel regression on ~15 obs overfits into colour noise.
+
+**Why Gemini's engine is clean (verified in GeminiWatermarkTool `src/core/watermark_engine.cpp`): its alpha map is the watermark stamped on a PURE-BLACK background**, where `watermarked = α·255 + (1-α)·0 = α·255`, so `alpha = capture/255` exactly -- no estimation. (`gemini_bg_*.png` is literally the sparkle in grey on black.) So the real Doubao unlock is the same controlled capture, **not more content images**. Black/white/gray seeds exist (`data/doubao_capture/seeds/seed_*_1x1_2048x2048.png`); a capture run (feed a black seed through doubao.com edit mode, download the *original*) was requested from the #13 reporter 2026-05-29. With ~2-3 black captures we get `α = capture/255` for free, Gemini-quality.
+
+**Until black captures arrive, the shipped direction is precise canonical glyph mask + inpaint (cv2 default, lama optional), NOT reverse-alpha.** The consensus glyph silhouette across the aligned marks distills cleanly (proto: a tight "豆包AI生成" strip, width ≈ 0.156 × image-width) and is good both as an exact inpaint mask and as an NCC localiser -- the latter also fixes the #23 detector false-positives (match the real glyph shape, not any bright low-saturation corner). Do **not** retry content-image reverse-alpha: it is data-limited by physics (no dark-background observations), not by effort.

 ## Watermarking landscape (research 2026-05-24)

 Who embeds what, and whether it is locally detectable (so we know which gaps are fillable). See `identify.py` for what we read.
 - **Locally detectable (open decoder, no key/API):** Stable Diffusion / SDXL / FLUX via `imwatermark` DWT-DCT (now covered by `invisible_watermark.py`). FLUX uses the same library (`black-forest-labs/flux2` `src/flux2/watermark.py`, 48-bit `0b001010101111111010000111100111001111010100101110`); SDXL is the diffusers `WATERMARK_MESSAGE` (`0b101100111110110010010000011110111011000110011110`). Caveat: fragile to re-encoding.
- **C2PA / IPTC (covered by the issuer/marker scan):** OpenAI, Google, Adobe Firefly, Microsoft (Designer + **Bing Image Creator** — collected 2026-05-24; Bing now runs Microsoft's own **MAI-Image** model, signs C2PA as "Microsoft", NOT OpenAI/DALL-E), and **Stability AI** (collected from Brand Studio / DreamStudio successor; signs C2PA as "Stability AI Ltd", no SynthID, no imwatermark on its current Stable Image model — issuer added to `C2PA_ISSUERS`). Still unsampled: Canva (its downloads are re-encoded design *exports* that strip C2PA, so a Canva "positive" is inconclusive — skipped), Getty, Shutterstock. Midjourney embeds NO C2PA and no invisible watermark (our `mj-*` sample carried only the IPTC tag).
+- **C2PA / IPTC (covered by the issuer/marker scan):** OpenAI, Google, Adobe Firefly, Microsoft (Designer + **Bing Image Creator** — collected 2026-05-24; Bing now runs Microsoft's own **MAI-Image** model, signs C2PA as "Microsoft", NOT OpenAI/DALL-E), and **Stability AI** (collected from Brand Studio / DreamStudio successor; signs C2PA as "Stability AI Ltd", no SynthID, no imwatermark on its current Stable Image model — issuer added to `C2PA_ISSUERS`). Still unsampled: Canva (its downloads are re-encoded design *exports* that strip C2PA, so a Canva "positive" is inconclusive — skipped), Getty, Shutterstock. Midjourney embeds NO C2PA and no invisible watermark (our `mj-*` sample carried only the IPTC tag). **Samsung Galaxy AI** (Generative Edit / Sketch to Image / Portrait Studio on Galaxy S23 FE / S24 / S25, One UI 7+) signs C2PA as "Samsung Galaxy" with the standard `trainedAlgorithmicMedia` source type AND a proprietary `genAIType` marker; verified on real signed files 2026-05-29 (the standard scan catches the source type; `genAIType` additionally catches a Galaxy S24 file that omits it). **ASUS Gallery** also signs edited photos as C2PA (`com.asus.gallery`) but with no AI source type — a signer, not an AI marker. **Black Forest Labs (FLUX)** API output signs C2PA: `claim_generator_info "Black Forest Labs API"` + a `c2pa.ai_generated_content` assertion + `trainedAlgorithmicMedia` (issuer `b"Black Forest Labs"` added to `C2PA_ISSUERS`, platform "Black Forest Labs (FLUX)"). **ByteDance Volcano Engine (Volcengine)** — the cloud behind Doubao / Jimeng — signs its AI image output with a cert from `certificate_center@volcengine.com` + `trainedAlgorithmicMedia` (issuer `b"volcengine"` → "ByteDance (Volcano Engine)", platform "ByteDance (Doubao / Jimeng / Volcano Engine)"); note this is the C2PA-signed surface, distinct from the XMP/PNG TC260 `AIGC` label Doubao also uses. All three verified on real signed files 2026-05-29.
 - **EXIF/XMP generator tag (caught by `exif_generator`):** **Ideogram** writes EXIF `Make="Ideogram AI"` (collected 2026-05-24 — no C2PA, no SynthID, no imwatermark; the Make tag is the only signal).
 - **xAI / Grok — its own EXIF signature scheme, NOT C2PA (DETECTED by `metadata.xai_signature`, built 2026-05-26).** Grok JPEG downloads (Aurora model) carry **no C2PA, no XMP, no SynthID, no IPTC** — only EXIF `Artist` = a UUID and EXIF `ImageDescription` = `Signature: <base64>` (a crypto signature, unverifiable locally without xAI's public key). This empirically kills the earlier unverified "xAI signs C2PA as xAI" lead — xAI is not even a C2PA member. `exif_generator` misses it (neither field holds an `AI_GENERATOR_TOKENS` token), so a dedicated detector `xai_signature(path)` matches the pair (`ImageDescription ~ ^Signature: [A-Za-z0-9+/=]{64,}` AND UUID `Artist`); wired into `has_ai_metadata`, `get_ai_metadata` (key `xai_signature`), and `identify` (signal `xai_signature`, platform "xAI (Grok / Aurora)"). **Format confirmed stable across n=3 genuine generations:** exactly three EXIF tags (`Artist`, `ExifOffset`, `ImageDescription`), `Signature:` prefix constant, base64 payload 300-1004 chars. Two capture facts: (a) the `Artist` UUID **equals the public image id** in the asset URL (`https://imagine-public.x.ai/imagine-public/images/<uuid>.jpg`), so it is NOT a private per-user secret — only the `Signature` blob is; (b) the Grok web-UI image is a re-encoded **WebP with no signature** — the EXIF survives only in the *original* JPEG (download button or that public tokenless URL), which is why screenshots / re-encodes are metadata-stripped. A real fixture `data/samples/grok-1.jpg` plus **synthetic** JPEG fixtures (fake UUID + fake `Signature:` blob) cover the detector; never add a real Grok image carrying private content (the repo is public). **Stripped on removal too:** `remove_ai_metadata` now calls `_scrub_ai_exif` on the JPEG EXIF, which deletes the xAI Signature+UUID-Artist pair **and** any `Software`/`Make`/`Artist`/`ImageDescription` tag holding an `AI_GENERATOR_TOKENS` token (so Ideogram's `Make="Ideogram AI"` is scrubbed too), while keeping genuine camera/editor EXIF. The shared `_is_xai_signature_pair` helper (module-level compiled regexes) is the single source of truth for the pattern, used by both `xai_signature` and `_scrub_ai_exif`. (AVIF/HEIF/JXL still strip only C2PA boxes via `isobmff`, not EXIF — unchanged.)
- **China TC260 AIGC label (caught by `AIGC_MARKERS` / `metadata.aigc_label`, surfaced by `identify` as the `aigc` signal):** China-served generators embed an XMP `<TC260:AIGC>{"Label":"1","ContentProducer":...}` block — China's mandatory AI-content labeling (TC260 namespace `tc260.org.cn/ns/AIGC`). **Doubao** (ByteDance) uses it (verified on the real #13 sample 2026-05-25; `ContentProducer` `001191110102MACQD9K64010000`, no C2PA/SynthID/imwatermark — the XMP block is the only signal; GitHub attachment upload did NOT strip it). The same standard is mandatory for Jimeng/Kling/Qwen/Ernie etc., so the one marker covers the whole China-AIGC-labeled ecosystem. `aigc_label` reads **two serializations** through a shared `_parse` helper: the HTML-entity-encoded XMP `<TC260:AIGC>` block (container-agnostic raw-byte scan, any JSON object accepted) **and** a raw-JSON PNG `AIGC` tEXt chunk — Doubao also writes the label this way, with no namespaced marker at all (confirmed on the corpus 2026-05-28, `ContentProducer="doubao"`). The PNG-chunk path is gated on at least one TC260 field (`_TC260_FIELDS`) so a generic `AIGC` key cannot false-positive. In `identify`, `aigc` fires on the parsed label **or** the `AIGC_MARKERS` byte scan (the latter preserves the laundering-tell case where the JSON payload is truncated).
+- **China TC260 AIGC label (caught by `AIGC_MARKERS` / `metadata.aigc_label`, surfaced by `identify` as the `aigc` signal):** China-served generators embed an XMP `<TC260:AIGC>{"Label":"1","ContentProducer":...}` block — China's mandatory AI-content labeling (TC260 namespace `tc260.org.cn/ns/AIGC`). **Doubao** (ByteDance) uses it (verified on the real #13 sample 2026-05-25; `ContentProducer` `001191110102MACQD9K64010000`, no C2PA/SynthID/imwatermark — the XMP block is the only signal; GitHub attachment upload did NOT strip it). The same standard is mandatory for Jimeng/Kling/Qwen/Ernie etc., so the one marker covers the whole China-AIGC-labeled ecosystem. `aigc_label` reads **three serializations** through a shared `_parse` helper: the HTML-entity-encoded XMP `TC260:AIGC` block in **either RDF form** — the nested element `<TC260:AIGC>{...}</TC260:AIGC>` (Doubao) or the attribute `TC260:AIGC="{...}"` (**PicWish**, `ContentProducer="picwish"`, verified on the corpus 2026-05-30) — via a container-agnostic raw-byte scan (any JSON object accepted), a raw-JSON PNG `AIGC` tEXt chunk (Doubao also writes the label this way, no namespaced marker at all — confirmed on the corpus 2026-05-28, `ContentProducer="doubao"`), **and** a bare raw-JSON `{"AIGC":{...}}` object embedded in **JPEG EXIF (UserComment)** by some China-served generators, brace-matched from the scan head with `json.JSONDecoder().raw_decode` (no namespaced marker, no PNG chunk — confirmed on the corpus 2026-05-30, `ContentProducer="001191440300708461136T1308L"`). Both generic forms (the PNG chunk and the bare `{"AIGC":...}` object) are gated on at least one TC260 field (`_TC260_FIELDS`) so a generic `AIGC` key cannot false-positive; the namespaced XMP element is unambiguous and needs no gate. In `identify`, `aigc` fires on the parsed label **or** the `AIGC_MARKERS` byte scan (the latter preserves the laundering-tell case where the JSON payload is truncated).
 - **HuggingFace-hosted job (caught by `metadata.huggingface_job`, surfaced by `identify` as the `hf_job` signal, MEDIUM confidence):** HuggingFace Jobs / Spaces stamp generated PNGs with an `hf-job-id` tEXt chunk holding the job UUID (3 on the corpus 2026-05-28, no other signal). It marks the *hosting job*, not a model — most commonly diffusion output — so it lifts an Unknown verdict to a tentative AI via `hf_only` (parallel to the visible sparkle) but never overrides a hard metadata signal; `_HF_JOB_CAVEAT` states the limit (job, not model; not proof of AI pixels). Stripped on removal (the PNG save whitelist keeps only `STANDARD_METADATA_KEYS`, so `hf-job-id` and the `AIGC` chunk are both dropped). The exact writer is not authoritatively documented (HF Jobs are generic GPU jobs), hence medium not high.
 - **No detectable signal on download (correctly reported `unknown`):** **Recraft** (PNG export is a re-encoded design export — strips everything), **Krea hosting FLUX 2** (no imwatermark despite FLUX — the host omits the encoder, same as Stability's hosted SDXL), and Midjourney (embeds nothing). Lesson: the imwatermark detector only fires on *pristine* output from a pipeline that runs the encoder (diffusers default, official BFL), not from re-hosts (Krea/Stability) or re-encoded exports (Recraft/Canva).
 - **Invisible but NOT locally detectable (proprietary, API/oracle only — same wall as SynthID):** Amazon Titan Image Generator + Nova Canvas (Bedrock `DetectGeneratedContent` API), Kakao (new SynthID image adopter, May 2026), NVIDIA Cosmos (SynthID video). No local detector possible; treat like SynthID.
@@ -8,6 +8,7 @@ Strips SynthID, C2PA Content Credentials, EXIF/XMP "Made with AI" labels, and vi
 >
 > No Python, no GPU, no setup. Visible-watermark and metadata removal are **free**. Invisible-watermark removal (SynthID / SDXL regeneration) normally needs a local GPU and ~2 GB of models. On **[raiw.cc](https://raiw.cc)** it runs on cloud GPUs in one click for a small per-image fee.

+[![Tests](https://github.com/wiltodelta/remove-ai-watermarks/actions/workflows/test.yml/badge.svg)](https://github.com/wiltodelta/remove-ai-watermarks/actions/workflows/test.yml)
 [![Sponsor](https://img.shields.io/badge/Sponsor-GitHub-db61a2?logo=githubsponsors&logoColor=white)](https://github.com/sponsors/wiltodelta)

 If this tool saves you time, consider [sponsoring its development](https://github.com/sponsors/wiltodelta).
@@ -16,7 +17,7 @@ If this tool saves you time, consider [sponsoring its development](https://githu

 ## Features

- **Visible watermark removal** — Gemini / Nano Banana sparkle logo (reverse alpha blending) and the Doubao "豆包AI生成" text strip (locate + mask + inpaint); fast, offline, deterministic, no GPU. `visible --mark auto` picks the right one
+- **Visible watermark removal** — a registry of known marks in their usual places: the Gemini / Nano Banana sparkle and the Doubao "豆包AI生成" text strip. Each is removed by **exact reverse-alpha blending** against a captured alpha map (`original = (wm − α·logo)/(1−α)`), recovering the true pixels rather than inpainting a guess. Fast, offline, no GPU. `visible --mark auto` finds and removes the strongest detected mark. (For arbitrary logos/objects, see `erase`.)
 - **Universal region eraser (`erase`)** — remove any logo / watermark / object inside boxes you specify, regardless of position or colour. Default cv2 inpainting (CPU, instant); optional big-LaMa via onnxruntime (`lama` extra) for higher quality
 - **Invisible watermark removal** — SynthID, StableSignature, TreeRing via diffusion-based regeneration (needs a local GPU, or run it with no setup on [raiw.cc](https://raiw.cc))
 - **AI metadata stripping** — EXIF, PNG text chunks, C2PA provenance manifests (PNG / JPEG / AVIF / HEIF / JPEG-XL, **MP4 / MOV / M4V / M4A** at the container level, and **WebM / MP3 / WAV / FLAC / OGG** losslessly via ffmpeg), XMP DigitalSourceType
@@ -25,7 +26,7 @@ If this tool saves you time, consider [sponsoring its development](https://githu
 - **Smart Face Protection** — automatic extraction and blending of human faces to prevent AI distortion
 - **Batch processing** — process entire directories
 - **Detection** — three-stage NCC watermark detection with confidence scoring
- **Provenance detection (`identify`)** — aggregate C2PA issuer, the C2PA soft-binding forensic-watermark vendor (Adobe TrustMark, Digimarc, Imatag, ...), IPTC "Made with AI" plus the IPTC 2025.1 `AISystemUsed` field, embedded SD/ComfyUI params, EXIF/XMP generator tags, the xAI/Grok EXIF signature, the China TC260 AIGC label (XMP or PNG chunk), the HuggingFace `hf-job-id` job marker, the SynthID metadata proxy, the visible sparkle, the open SD/SDXL/FLUX invisible watermark, and (with the `trustmark` extra) the open Adobe TrustMark watermark into one origin-platform + watermark-inventory verdict (`--json` for machine output)
+- **Provenance detection (`identify`)** — aggregate C2PA issuer, the C2PA soft-binding forensic-watermark vendor (Adobe TrustMark, Digimarc, Imatag, ...), IPTC "Made with AI" plus the IPTC 2025.1 `AISystemUsed` field, embedded SD/ComfyUI params, EXIF/XMP generator tags, the xAI/Grok EXIF signature, the China TC260 AIGC label (XMP, PNG chunk, or EXIF), the HuggingFace `hf-job-id` job marker, the SynthID metadata proxy, the visible sparkle, the open SD/SDXL/FLUX invisible watermark, and (with the `trustmark` extra) the open Adobe TrustMark watermark into one origin-platform + watermark-inventory verdict (`--json` for machine output)

 ## Examples

@@ -48,13 +49,15 @@ If this tool saves you time, consider [sponsoring its development](https://githu
 | **xAI Grok (Aurora)** | — | — | ✅ EXIF signature scheme (no C2PA): `Signature:` blob + UUID `Artist` | Detected (`identify`); metadata strip |
 | **Midjourney** | — | — | ✅ EXIF + XMP (prompt, model, seed) | Metadata strip |
 | **Meta AI** | — | — | ✅ IPTC "Made with AI" (digitalSourceType) | Metadata strip (removes the label) |
-| **Doubao** (ByteDance) / China AIGC generators | ✅ "豆包AI生成" text strip (bottom-right) | — | ✅ TC260 AIGC label — `<TC260:AIGC>` XMP **or** `AIGC` PNG chunk (China's mandatory AI labeling) | Locate + mask + inpaint (cv2, CPU) + metadata strip |
+| **Doubao** (ByteDance) / China AIGC generators | ✅ "豆包AI生成" text strip (bottom-right) | — | ✅ TC260 AIGC label (`<TC260:AIGC>` XMP, `AIGC` PNG chunk, or EXIF JSON) **+ C2PA** signed by ByteDance Volcano Engine (`volcengine`) | Exact reverse-alpha (captured α map): pixel-exact at native width, NCC-aligned at other resolutions, + metadata strip |
+| **Samsung Galaxy AI** (Generative Edit, Sketch to Image, ...) | — | — | ✅ C2PA (signer "Samsung Galaxy") + `trainedAlgorithmicMedia` / proprietary `genAIType` marker | Detected (`identify`) + metadata strip |
+| **Black Forest Labs** (FLUX API) | — | — | ✅ C2PA (`Black Forest Labs API` + `c2pa.ai_generated_content` + `trainedAlgorithmicMedia`) | Metadata strip |
 | **StableSignature** (Meta) | — | ✅ In-model watermark | — | Diffusion regeneration |
 | **TreeRing** | — | ✅ Latent space watermark | — | Diffusion regeneration |

 > Visible overlays are used by Google Gemini / Nano Banana (sparkle logo) and by Doubao / China AIGC generators (the mandated "...AI生成" corner text). Both are removed deterministically on CPU. Other services rely on invisible watermarks and/or metadata; our diffusion-based regeneration works against any invisible watermark in pixel or frequency domain. For a visible mark from any other source (any position, any colour), use the universal `erase --region` command.

-> **Detection:** `remove-ai-watermarks identify <image>` reports the origin platform and watermark inventory for all the signals above — C2PA issuer, the C2PA soft-binding forensic-watermark vendor (TrustMark / Digimarc / Imatag / ...), IPTC "Made with AI" plus the IPTC 2025.1 `AISystemUsed` field, the China TC260 AIGC label (XMP or PNG chunk), the HuggingFace `hf-job-id` job marker, embedded generation params, EXIF/XMP generator tags, the xAI/Grok EXIF signature, the SynthID metadata proxy, the visible sparkle, and (with the `[detect]` / `[trustmark]` extras) the open SD/SDXL/FLUX and Adobe TrustMark invisible watermarks. SynthID and the proprietary soft-binding watermarks (Digimarc etc.) have no local decoder, so they are reported by metadata proxy / vendor name only.
+> **Detection:** `remove-ai-watermarks identify <image>` reports the origin platform and watermark inventory for all the signals above — C2PA issuer, the C2PA soft-binding forensic-watermark vendor (TrustMark / Digimarc / Imatag / ...), IPTC "Made with AI" plus the IPTC 2025.1 `AISystemUsed` field, the China TC260 AIGC label (XMP, PNG chunk, or EXIF), the HuggingFace `hf-job-id` job marker, embedded generation params, EXIF/XMP generator tags, the xAI/Grok EXIF signature, the SynthID metadata proxy, the visible sparkle, and (with the `[detect]` / `[trustmark]` extras) the open SD/SDXL/FLUX and Adobe TrustMark invisible watermarks. SynthID and the proprietary soft-binding watermarks (Digimarc etc.) have no local decoder, so they are reported by metadata proxy / vendor name only.

 ## How it works

@@ -78,9 +81,9 @@ A three-stage NCC (Normalized Cross-Correlation) detector finds the watermark po

 ### Removing the Doubao "豆包AI生成" text watermark

-Doubao (ByteDance) stamps every output with a light, semi-transparent "豆包AI生成" text strip in the bottom-right corner — the visible AIGC label mandated by China's TC260 standard. Unlike the fixed-size Gemini sparkle, it is a text strip that scales with image width, so we anchor a generous bottom-right box by geometry, extract the light low-saturation glyph pixels with a polarity-aware white top-hat mask, and inpaint them (cv2 Telea/NS). The mask is background-relative, so it leaves white-paper documents untouched instead of smearing their text. On dense-text backgrounds where the mask would explode, removal is skipped rather than guessed.
+Doubao (ByteDance) stamps every output with a light, semi-transparent "豆包AI生成" text strip in the bottom-right corner — the visible AIGC label mandated by China's TC260 standard. It is a fixed semi-transparent white overlay, so — like the Gemini sparkle — it is removed by **exact reverse-alpha blending**: `original = (watermarked - α·logo) / (1 - α)`, recovering the true pixels instead of hallucinating them. The α map and logo colour were solved from controlled black + gray captures (on black, `captured = α·logo`; the black/gray pair solves α per-pixel). At the captured width the placement is exact, so the recovery is returned untouched (inpainting over exactly-recovered pixels only degrades them). The single capture generalizes to any resolution: off the captured width an NCC scale-and-position search registers the α template to the actual mark, and a light residual inpaint cleans the sub-pixel seam there. Detection is consistent with removal: it matches the same alpha glyph silhouette against the corner (normalized correlation), so it keys on the actual "豆包AI生成" shape, not on textured corners.

-**Speed**: ~0.03s per image. No GPU needed. Best on photo / illustration backgrounds; on high-contrast edges a faint residue can remain (use `erase --backend lama` for neural-quality fill).
+**Speed**: ~0.05s, no GPU needed. Reverse-alpha at the captured resolution recovers the true background pixels exactly.

 ### Universal region eraser

@@ -107,7 +110,7 @@ SDXL is the default since May 2026: empirically defeats SynthID v2 on Gemini 3 P

 **Analog Humanizer**: optional film grain and chromatic aberration injection that mimics a photo of a screen, raising the bar for AI-generated image classifiers. (It frustrates generic classifiers but does not guarantee forensic invisibility — see the [arXiv:2605.09203](https://arxiv.org/abs/2605.09203) note above.)

-**Text Protection** (automatic): SDXL img2img regenerates every pixel, so small text and CJK glyphs get deformed at the strengths that defeat SynthID. The SDXL pipeline guards against this by default: a CJK-native PP-OCRv3 text detector (a 2.4 MB ONNX model run on CPU via OpenCV's DNN module, downloaded and cached on first use) locates text regions, and if any are found the pass switches to Differential Diffusion so a per-pixel change map keeps the text regions largely intact while the background is regenerated normally. Text-free images run the standard pass at no extra cost. Pass `--no-protect-text` to turn it off. SDXL default pipeline only.
+**Text Protection** (automatic): SDXL img2img regenerates every pixel, so small text and glyphs get deformed at the strengths that defeat SynthID. The SDXL pipeline guards against this by default: a PP-OCRv3 text detector (a 2.4 MB ONNX model run on CPU via OpenCV's DNN module, downloaded and cached on first use) locates text regions, and if any are found the pass switches to Differential Diffusion so a per-pixel change map keeps the text regions largely intact while the background is regenerated normally. Detection is **language-agnostic** (it finds text regions, not characters), so Latin, Cyrillic, CJK, Hangul, Arabic, and digits are all protected, and it runs at the image's native resolution so small text on large images is not missed. Text-free images run the standard pass at no extra cost. Pass `--no-protect-text` to turn it off. SDXL default pipeline only.

 ### Stripping C2PA, EXIF, and "Made with AI" metadata

@@ -236,9 +239,9 @@ remove-ai-watermarks batch ./images/ --mode all
 # of a clean origin. Add --json for machine-readable output.
 remove-ai-watermarks identify image.png

-# Visible watermark only — fast, offline, CPU. --mark auto (default) picks
-# between the Gemini sparkle and the Doubao "豆包AI生成" text strip; force one
-# with --mark gemini / --mark doubao.
+# Visible watermark only — fast, offline, CPU. --mark auto (default) finds the
+# strongest known mark (Gemini sparkle / Doubao "豆包AI生成" text); force one
+# with --mark gemini / doubao. Removed by exact reverse-alpha (true-pixel recovery).
 remove-ai-watermarks visible image.png -o clean.png

 # Erase arbitrary region(s) — universal, any logo/watermark/object, any position.
@@ -328,7 +331,7 @@ Tracked but not yet implemented:
 - **Real non-PNG C2PA fixtures**. SynthID-source detection for JPEG / WebP / AVIF is currently covered only by synthetic byte blobs; replace with real vendor-emitted files to ground the binary-scan path.
 - **Maintenance debt**. Strict pyright is now clean across `src/` (0 errors): pure-logic files are fully typed, the cv2 / torch / diffusers boundary files carry a documented per-file relax pragma, and a local `typings/piexif` stub covers piexif. Remaining: full-project `pyright` (no path) still OOMs node on this ML-heavy repo, so it must be scoped to `src/`; narrowing the boundary pragmas back toward full strict (as upstream stubs improve) is the long tail. (`uv-secure` is already clean since `idna` was bumped to 3.16.)
 - **AVIF / HEIF `Exif` item inside the `meta` box**. An AI-label *XMP* packet in a `meta`-box item is now blanked in place (v0.6.9), but EXIF stored as a `meta`-box `Exif` *item* is still not removed — it needs full `iinf`/`iloc` surgery (offset rewrite, corruption risk) or `exiftool` (a non-bundled binary dependency). Low priority: the AI labels we target are XMP, not EXIF, so an EXIF-only meta-box case is rare.
- **More C2PA device signers**. Leica, Nikon, Google Pixel, Sony, and Truepic are mapped (each verified against a real signed file). Canon and Samsung Galaxy (AI-edit) are deferred until a real signed sample surfaces — no public direct-download C2PA file exists for them today (upload-to-verify / news-agency-licensed only).
+- **More C2PA device signers**. Leica, Nikon, Google Pixel, Sony, and Truepic capture cameras are mapped (each verified against a real signed file); **Samsung Galaxy AI**, **Black Forest Labs (FLUX)**, and **ByteDance Volcano Engine** (Doubao / Jimeng) are now attributed too (verified on real signed files). Canon is still deferred until a real signed sample surfaces — no public direct-download C2PA file exists for it today (upload-to-verify / news-agency-licensed only).
 - **Resemble PerTh audio detection** — evaluated, not feasible with the public API: `get_watermark()` returns a raw bit array with no presence/confidence flag, so watermarked vs. clean audio can't be reliably separated without Resemble's fixed payload or a confidence service. Same wall as the SynthID pixel detector.
 - **Video pipeline (`noai-video`)**: per-frame inpainting and tracking for Sora 2 dynamic logo, Veo 3.1 badge, Kling, Runway. Separate package, not folded into this repo.

@@ -0,0 +1,138 @@
+# Text protection research: crisp text under a "watermark removed everywhere" constraint
+
+Date: 2026-05-29. Source: a deep-research run (104 agents, 5 search angles, sources
+fetched and 3-vote adversarially verified). Not committed automatically — saved as a
+research note for the next session.
+
+## The constraint that frames everything
+
+The invisible watermark (Google SynthID) must be removed **everywhere, including inside
+text regions**. Therefore any technique that keeps or composites the **original
+(watermarked) text pixels** is disqualified — the text must be *regenerated / freshly
+synthesized* enough to scrub the watermark, yet rendered crisply. This single rule is the
+filter applied to every candidate below.
+
+## Problem recap
+
+The `invisible` pipeline is SDXL base 1.0 img2img at low strength (~0.05) to defeat
+SynthID with minimal visible change. Text is protected via Differential Diffusion with a
+per-pixel change map (`preserve` ~0.9) driven by the PP-OCRv3 DB detector
+(`text_protector.py`). Large text survives; **small text (sub ~8 px strokes) softens or
+garbles** (issue #14, confirmed on real content).
+
+## Executive summary
+
+The fine-text softening is an **architectural consequence of latent-space processing, not
+a tuning problem**: SDXL's 4-channel VAE (~48x compression) discards high-frequency signal
+on encode, and Differential Diffusion blends in latent space with the change map
+downsampled by 8x, so any stroke under ~8 px sits inside one latent cell and cannot be
+preserved or edited cleanly **regardless of `preserve`** (the Differential Diffusion
+authors state this limit explicitly). Two structurally sound directions keep the
+"watermark removed everywhere" guarantee because they **synthesize fresh glyph pixels**
+rather than compositing originals: (1) glyph/text-conditioned diffusion re-render of
+detected text (AnyText2, EasyText), and (2) a two-stage architecture — global scrub, then
+a dedicated text-restoration / text-aware super-resolution pass over detected regions
+(TIGER, TextSR, TeReDiff/TAIR). **EasyText** and **TextSR** are the most promising for this
+CJK-first pipeline (both multilingual via DiT/ByT5, both regenerate from glyph or
+character-shape priors). The deepest fix — a 16-channel (SD3/FLUX) VAE — materially reduces
+the softening but means switching the base model, not a drop-in VAE swap.
+
+## Constraint reconciliation (important)
+
+The generic research "quick win: bump `preserve` toward 1.0" is **invalid under our hard
+constraint**: raising `preserve` freezes the text region, so SynthID there is **not
+scrubbed**. Likewise, pixel paste-back of the original text is disqualified. The only
+constraint-compatible quick win is **higher resolution / tiled diffusion** (strokes span
+more latent cells, less VAE softening, while the text is still fully regenerated and thus
+scrubbed). The real answer is **regenerate text crisply**, not freeze it.
+
+## Findings (with confidence and sources)
+
+### Finding 1 — confidence: high
+
+**Claim.** The small-text softening is an architectural latent-space limit, not a tuning issue. SDXL's VAE compressively encodes (losing exact color and fine detail on every round-trip), and Differential Diffusion blends in latent space with the change map downsampled to latent resolution (8x), so the method explicitly caps edit/preserve granularity at ~8 px under SD settings. Text strokes below one latent cell cannot be cleanly preserved even at preserve ~0.9.
+
+**Evidence.** Differential Diffusion's paper states a "cap on the resolution of the change map ... can limit the ability to precisely edit small objects (less than 8 pixels for Stable-Diffusion's settings)"; the official SDXL pipeline downsamples the map by `vae_scale_factor=8` and blends `latents = original*mask + latents*(1-mask)` in latent space. The VAE encode is "compressive ... exact color qualities and exact visual fine-details are lost." arXiv:2512.05198 confirms "resizing the pixel mask to latent resolution discards fine structure ... downsamples by 1/8" and that linear latent blending "cannot be pixel-equivalent." Higher compression = more high-frequency loss (arXiv:2305.02541).
+
+**Sources.** https://onlinelibrary.wiley.com/doi/10.1111/cgf.70040 · https://differential-diffusion.github.io/ · https://github.com/exx8/differential-diffusion · https://arxiv.org/abs/2512.05198 · https://omriavrahami.com/blended-latent-diffusion-page/ · https://arxiv.org/pdf/2305.02541
+
+### Finding 2 — confidence: low (do not build on it yet)
+
+**Claim.** Pixel-space differential / blended-latent variants exist as a research direction, but the specific full-resolution-mask solution (PELC/DecFormer, arXiv:2512.05198) was NOT verified to deliver its claimed seam/edge improvements.
+
+**Evidence.** arXiv:2512.05198 argues linear latent blending is not pixel-equivalent and proposes decoder-equivariant compositing; PixPerfect (arXiv:2512.03247) does pixel-space refinement of chromatic shifts at edit boundaries. But the specific PELC full-resolution-mask and DecFormer "53% error reduction" claims were **refuted on adversarial vote (0-3 and 1-2)**. Treat pixel-equivalent latent compositing as an emerging idea to watch, not a production fix.
+
+**Sources.** https://arxiv.org/abs/2512.05198 · https://arxiv.org/abs/2512.03247
+
+### Finding 3 — confidence: high
+
+**Claim.** Glyph/text-conditioned diffusion can re-render detected text as freshly synthesized pixels (not copied), which inherently scrubs any watermark in the text region while rendering glyphs crisply. AnyText/AnyText2 inject text-rendering into a pretrained T2I model and support generation AND editing of existing scene images; multilingual including CJK and English.
+
+**Evidence.** AnyText2 "enables precise control over multilingual text attributes in natural scene image generation and editing" (WriteNet+AttnX); +3.3% (Chinese) / +9.3% (English) accuracy over AnyText v1. AnyText "can be plugged into existing diffusion models ... for rendering or editing text" and synthesizes text latent features through diffusion (fresh pixels), supporting zh/en/ja/ko/ar/bn/hi. **Caveat:** both are SD1.5-based, so NOT a drop-in into the SDXL scrub (separate base model); AnyText's own limitation: "the inpainting manner ... impedes editing quality on small text," and it ranks weak on STRICT (EMNLP 2025) — small-text crispness not guaranteed.
+
+**Sources.** https://github.com/tyxsspa/AnyText2 · https://arxiv.org/abs/2411.15245 · https://arxiv.org/abs/2311.03054
+
+### Finding 4 — confidence: high
+
+**Claim.** EasyText is a strong glyph-conditioned re-render candidate: built on the FLUX-dev DiT framework with LoRA tuning, renders compact per-character glyph patches (64px-high adaptive for alphabetic, 64x64 for logographic) concatenated in latent space, supports 10+ languages including Chinese, Japanese, Korean, Thai, Vietnamese, Greek, and Latin.
+
+**Evidence.** AAAI 2025 + arXiv:2505.24417: "implemented based on the open-source FLUX-dev framework with LoRA-based parameter-efficient tuning," VAE and text encoder frozen, two-stage 512->1024 training. Glyph conditioning via "64-pixel-high images ... adaptive widths for alphabetic; fixed 64x64 for logographic," VAE-encoded and concatenated with denoised latents, "less than one-tenth the spatial size of layout-matching methods." FLUX-based (16-channel VAE, DiT) also sidesteps the SDXL 4-channel wall. Fresh-pixel generation preserves the watermark-removal guarantee. Cyrillic/Arabic crispness not separately benchmarked.
+
+**Sources.** https://arxiv.org/html/2505.24417 · https://ojs.aaai.org/index.php/AAAI/article/view/37697
+
+### Finding 5 — confidence: high
+
+**Claim.** A two-stage "global watermark scrub then text-restoration pass" architecture is validated by recent literature, and the restoration stage can synthesize glyph pixels from priors (no original-pixel reintroduction). TIGER reconstructs stroke geometry then injects it as guidance into full-image super-resolution; TextSR uses a detector + multilingual OCR to regenerate text from character-shape priors; TeReDiff/TAIR couples a jointly-trained text-spotter with diffusion.
+
+**Evidence.** TIGER (arXiv:2510.21590): "a diffusion-based local text refiner ... reconstructing fine-grained stroke geometry ... injected as conditional guidance into the subsequent full-image restoration." TextSR (arXiv:2505.23119, Google): "leverages a text detector ... then employs OCR to extract multilingual text," regenerating from "multilingual character-to-shape diffusion priors" that "produce character shapes solely based on text prompts, even without visual input" — fresh pixels. TAIR/TeReDiff (ICLR 2026): standard restoration "frequently generates plausible but incorrect textures"; TeReDiff feeds text-spotter outputs back as prompts. **Caveat:** TIGER orders text-first then global (reverse of scrub-then-text); these target degraded-input super-resolution, not watermark removal, so the SynthID-scrub of the restoration stage must be verified empirically (the stages are themselves diffusion-based, so fresh-pixel = no SynthID is plausible but unproven here).
+
+**Sources.** https://arxiv.org/html/2510.21590v1 · https://arxiv.org/html/2505.23119v1 · https://cvlab-kaist.github.io/TAIR/ · https://arxiv.org/abs/2506.09993
+
+### Finding 6 — confidence: high
+
+**Claim.** Switching to a 16-channel VAE (SD3/FLUX class) materially reduces small-text/latent softening vs SDXL's 4-channel VAE, but it requires switching the base model — not a drop-in latent swap into an SDXL UNet img2img pipeline. RAE approaches are DiT-native and likewise not drop-in.
+
+**Evidence.** SD3/FLUX moved from 4-channel (48x) to 16-channel (12x) VAEs specifically to preserve fine detail (diffusers Discussion #8713; madebyollin VAE notes; arXiv:2305.02541). RAE (arXiv:2510.11690) "should be the new default for diffusion transformer training" but produces high-dimensional latents needing a DiT wide-DDT head — NOT compatible with an SDXL 4-channel UNet. EasyText shows the practical path: adopt a FLUX-DiT base rather than retrofit SDXL. The VAE upgrade couples to a base-model migration.
+
+**Sources.** https://arxiv.org/abs/2510.11690 · https://arxiv.org/pdf/2305.02541 · https://arxiv.org/html/2505.24417
+
+## Recommendation
+
+Under the hard constraint, the correct architecture is **not "protect text during the
+scrub" (Differential Diffusion)** but **"scrub everywhere, then restore text crisply by
+regeneration"**:
+
+1. Global SDXL scrub with text protection OFF (text region is scrubbed too).
+2. On detected text regions, a **glyph-conditioned restoration** that re-renders the same
+   glyphs as fresh pixels (no original reused).
+
+This is the only path that delivers both "watermark everywhere" and crisp text.
+
+**Top-2 to prototype:**
+- **TextSR** — detector + multilingual OCR + character-shape diffusion priors; closest to
+  the existing detector-driven pipeline.
+- **EasyText** — FLUX-DiT glyph re-render, multilingual incl. CJK; also gets the 16-channel
+  VAE for free.
+
+**Honest costs / unknowns:** this is a re-architecture, not a quick fix. It needs a new
+**OCR-recognition** step (we currently only detect text; we must know *what* to re-render).
+Models are FLUX/DiT-class (heavy) -> serverless GPU. Maturity is research-grade; CJK is
+covered, Cyrillic/Arabic crispness is not separately benchmarked -> a prototype must
+measure real fidelity. The restoration stage being diffusion-based makes "fresh pixels =
+no SynthID" plausible but **must be verified empirically** (run the SynthID oracle on the
+restored output).
+
+**Constraint-compatible quick win to try first:** run the global scrub at **higher
+resolution / tiled** so strokes exceed the latent cell — less softening, full scrub, no
+freezing. Cheap to test; quantify recall/quality vs cost.
+
+**Do not pursue:** raising `preserve` toward 1.0 or pixel paste-back (both leave original
+watermarked pixels in text); PELC/DecFormer pixel-equivalent latent compositing (refuted,
+not production-ready).
+
+## Provenance
+
+Deep-research workflow run `wf_118b9a03-3eb` (2026-05-29). Findings adversarially verified
+(2/3 refutes required to kill a claim). This note records research only; no code change is
+implied until a prototype validates fidelity and the SynthID-scrub guarantee on the
+restored output.
@@ -1,10 +1,20 @@
 [project]
 name = "remove-ai-watermarks"
-version = "0.6.12"
+version = "0.7.0"
 description = "Remove visible and invisible AI watermarks from images (Gemini / Nano Banana, ChatGPT, Stable Diffusion)"
 readme = "README.md"
 requires-python = ">=3.10"
 license = {text = "MIT"}
+classifiers = [
+    "License :: OSI Approved :: MIT License",
+    "Operating System :: OS Independent",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
+    "Topic :: Multimedia :: Graphics",
+    "Topic :: Scientific/Engineering :: Image Processing",
+]
 dependencies = [
    "pillow>=10.0.0",
    "piexif>=1.1.3",
@@ -18,6 +28,15 @@ dependencies = [
 [project.optional-dependencies]
 gpu = [
    "torch>=2.0.0",
+    # The default PyPI torch wheel is a CPU/CUDA build. To drive an Intel GPU
+    # (Arc / Data Center) via ``--device xpu`` you need an XPU-enabled torch
+    # from PyTorch's XPU wheel index (Linux/Windows only -- there is no macOS
+    # XPU build). Install that build first, then this extra (torch is then
+    # already satisfied and won't be re-pulled):
+    #   pip install torch --index-url https://download.pytorch.org/whl/xpu
+    #   pip install 'remove-ai-watermarks[gpu]'
+    # uv users can target the ``pytorch-xpu`` index declared under [tool.uv]:
+    #   uv pip install torch --index-url https://download.pytorch.org/whl/xpu
    "diffusers>=0.38.0",
    # diffusers 0.38's auto-pipeline registry imports ``Qwen3VLForConditional
    # Generation`` (its ``nucleusmoe_image`` pipeline), which only exists in
@@ -77,6 +96,15 @@ all = ["remove-ai-watermarks[gpu,detect,trustmark,lama,dev]"]
 [tool.uv]
 prerelease = "allow"

+# PyTorch Intel-GPU (XPU) wheel index. ``explicit = true`` keeps it inert for
+# the default CPU/CUDA install: uv consults it only when a torch install
+# explicitly targets it (see the ``gpu`` extra comment), so it does not alter
+# the locked CPU/CUDA resolution. Linux/Windows only -- no macOS XPU build.
+[[tool.uv.index]]
+name = "pytorch-xpu"
+url = "https://download.pytorch.org/whl/xpu"
+explicit = true
+
 [project.scripts]
 remove-ai-watermarks = "remove_ai_watermarks.cli:main"

@@ -0,0 +1,215 @@
+"""Audit a local image corpus against the library's own ``identify`` detector.
+
+Two jobs in one pass:
+
+1. **Report** -- run ``identify`` over every image and write one CSV row per file
+   (verdict, platform, confidence, watermarks, signals, integrity clashes).
+2. **Gap audit** -- for every ``unknown``-verdict file, scan only its *metadata
+   region* (PNG text/eXIf chunks, JPEG APPn segments before SOS, or the file
+   head for other containers) for known provenance markers. A marker found there
+   on a file the detector calls ``unknown`` is a concrete lib gap: a serialization
+   or generator we do not yet parse. Scanning the metadata region -- not the whole
+   file -- is deliberate: short tokens collide randomly inside compressed PNG
+   ``IDAT`` / JPEG scan data, which produced false "xAI/Flux/AIGC" hits when the
+   first audit naively scanned the first megabyte.
+
+This is how new detector gaps get found (it is what surfaced the JPEG-EXIF
+``{"AIGC":{...}}`` form). Re-run after collecting a fresh corpus batch.
+
+Usage:
+    uv run python scripts/corpus_gap_scan.py --corpus data/spaces/originals
+    uv run python scripts/corpus_gap_scan.py --corpus data/spaces/originals \\
+        --report data/spaces/detector_report.csv
+"""
+
+from __future__ import annotations
+
+import csv
+import logging
+from collections import Counter
+from pathlib import Path
+
+import click
+from rich.console import Console
+from rich.table import Table
+
+from remove_ai_watermarks.identify import identify
+from remove_ai_watermarks.metadata import _png_late_metadata
+
+log = logging.getLogger(__name__)
+console = Console()
+
+# Distinctive, multi-byte provenance markers worth flagging when they appear in a
+# file the detector calls `unknown`. Kept long enough that a random collision in a
+# (non-scanned) compressed stream is implausible; the metadata-region restriction
+# below is the primary guard, this list is the second. Group: C2PA/JUMBF infra,
+# AI source-type / labeling schemes, and distinctive generator name strings.
+MARKERS: tuple[bytes, ...] = (
+    # C2PA / JUMBF infrastructure and AI source-type / labeling schemes.
+    b"c2pa",
+    b"jumbf",
+    b"contentauth",
+    b"trainedAlgorithmicMedia",
+    b"digitalSourceType",
+    b'"AIGC"',
+    b"<TC260:AIGC>",
+    b"TC260:AIGC",
+    b"tc260.org.cn",
+    b"AISystemUsed",
+    b"SynthID",
+    b"hf-job-id",
+    b"genAIType",
+    b"PhotoEditor_Re_Edit",
+    b"Signature:",
+    # Distinctive multi-word generator strings only. Bare single words (Luma,
+    # Gemini, Sora, ...) are omitted: they collide with unrelated metadata prose
+    # (e.g. "Luma" in Lightroom's EnhanceDenoiseLumaAmount), defeating precision.
+    b"Midjourney",
+    b"Stable Diffusion",
+    b"StableDiffusion",
+    b"ComfyUI",
+    b"Automatic1111",
+    b"DALL-E",
+    b"Ideogram AI",
+    b"Adobe Firefly",
+    b"Black Forest",
+    b"volcengine",
+    b"Doubao",
+    b"\xe8\xb1\x86\xe5\x8c\x85",
+    b"Nano Banana",
+    b"Stability AI",
+    b"Samsung Galaxy",
+)
+
+
+def _metadata_region(path: Path) -> bytes:
+    """Return only the bytes where provenance metadata can live, never the
+    compressed pixel stream (which produces random short-token collisions)."""
+    try:
+        head = path.read_bytes()
+    except OSError:
+        return b""
+    if head[:8] == b"\x89PNG\r\n\x1a\n":
+        # All ancillary metadata chunks (window=0), via the library's own walker.
+        return _png_late_metadata(path, 0)
+    if head[:2] == b"\xff\xd8":  # JPEG: APPn segments up to Start-Of-Scan
+        out = bytearray()
+        p = 2
+        n = len(head)
+        while p + 4 <= n and head[p] == 0xFF:
+            marker = head[p + 1]
+            if marker == 0xDA:  # SOS -> compressed scan data follows
+                break
+            seg_len = (head[p + 2] << 8) | head[p + 3]
+            out += head[p + 4 : p + 2 + seg_len]
+            p += 2 + seg_len
+        return bytes(out)
+    return head[:65536]  # webp/avif/heif/jxl: metadata sits near the head
+
+
+def _row(rep) -> dict[str, str]:  # noqa: ANN001 (ProvenanceReport)
+    return {
+        "path": "",  # filled by caller (relative)
+        "is_ai": str(rep.is_ai_generated),
+        "platform": rep.platform or "",
+        "confidence": rep.confidence,
+        "watermarks": "|".join(rep.watermarks),
+        "signals": "|".join(s.name for s in rep.signals),
+        "integrity_clashes": "|".join(rep.integrity_clashes),
+    }
+
+
+@click.command()
+@click.option(
+    "--corpus",
+    type=click.Path(exists=True, file_okay=False, path_type=Path),
+    default=Path("data/spaces/originals"),
+    show_default=True,
+    help="Directory of images to scan (recursively).",
+)
+@click.option(
+    "--report",
+    type=click.Path(path_type=Path),
+    default=None,
+    help="Write the per-file CSV here (default: <corpus>/../detector_report.csv).",
+)
+@click.option("--limit", type=int, default=0, help="Scan at most N files (0 = all).")
+def main(corpus: Path, report: Path | None, limit: int) -> None:
+    logging.basicConfig(level=logging.WARNING, format="%(message)s")
+    report = report or corpus.parent / "detector_report.csv"
+
+    files = sorted(p for p in corpus.rglob("*") if p.is_file())
+    if limit:
+        files = files[:limit]
+    console.print(f"Scanning [bold]{len(files)}[/bold] files under {corpus} ...")
+
+    verdicts: Counter[str] = Counter()
+    platforms: Counter[str] = Counter()
+    gap_tokens: Counter[str] = Counter()
+    gaps: list[tuple[str, list[str]]] = []
+    rows: list[dict[str, str]] = []
+    errors = 0
+
+    with click.progressbar(files, label="identify") as bar:
+        for p in bar:
+            rel = str(p.relative_to(corpus))
+            try:
+                rep = identify(p)
+            except Exception as exc:
+                log.warning("identify failed on %s: %s", rel, exc)
+                errors += 1
+                continue
+            row = _row(rep)
+            row["path"] = rel
+            rows.append(row)
+            if rep.is_ai_generated:
+                verdicts["ai"] += 1
+                platforms[rep.platform or "?"] += 1
+                continue
+            verdicts["unknown"] += 1
+            # A gap candidate is a file identify is *blind* to (no signal at all)
+            # yet whose metadata carries a known marker. A file that produced a
+            # signal but no AI verdict (e.g. an ASUS Gallery C2PA signer, which we
+            # attribute but do not call AI) is handled correctly -- not a gap.
+            if rep.signals:
+                continue
+            region = _metadata_region(p)
+            hits = sorted({m.decode("latin-1", "replace") for m in MARKERS if m in region})
+            if hits:
+                gaps.append((rel, hits))
+                gap_tokens.update(hits)
+
+    with report.open("w", newline="") as f:
+        writer = csv.DictWriter(
+            f,
+            fieldnames=["path", "is_ai", "platform", "confidence", "watermarks", "signals", "integrity_clashes"],
+        )
+        writer.writeheader()
+        writer.writerows(rows)
+    console.print(f"\nWrote [bold]{len(rows)}[/bold] rows -> {report}")
+
+    console.print(f"\n[bold]Verdicts:[/bold] AI {verdicts['ai']} | unknown {verdicts['unknown']} | errors {errors}")
+    plat = Table(title="AI platforms", show_header=False)
+    for name, n in platforms.most_common():
+        plat.add_row(str(n), name)
+    console.print(plat)
+
+    if gaps:
+        console.print(
+            f"\n[bold red]Gap candidates[/bold red]: {len(gaps)} unknown files carry a known "
+            f"marker in their metadata region (potential undetected serialization/generator):"
+        )
+        tok = Table(title="markers seen in unknown files")
+        tok.add_column("count", justify="right")
+        tok.add_column("marker")
+        for name, n in gap_tokens.most_common():
+            tok.add_row(str(n), name)
+        console.print(tok)
+        for rel, hits in gaps:
+            console.print(f"  {rel}  ->  {', '.join(hits)}")
+    else:
+        console.print("\n[green]No gap candidates: every unknown file is metadata-free.[/green]")
+
+
+if __name__ == "__main__":
+    main()
@@ -0,0 +1,150 @@
+"""Multilingual recall benchmark for the text-protection detector.
+
+Measures the core lever of text protection (`text_protector.TextProtector`): if
+the PP-OCRv3 DB detector misses a text region, that text is NOT preserved during
+the SDXL watermark-removal pass and gets deformed (issue #14). This renders short
+text in several scripts at several font sizes on two canvas sizes, runs detection,
+and reports the fraction of each known text bbox the detector covers.
+
+Findings (2026-05-29):
+  - Detection is script-agnostic: DB segments text *regions*, not characters, so
+    Latin / Cyrillic / CJK / Hangul / Arabic / digits score identically. Language
+    was never the lever.
+  - The only lever is resolution. A fixed small detector input downscaled large
+    canvases so far that small text was missed. Detecting at the native long side
+    (capped, see ``text_protector._DET_MAX_LONG_SIDE``) lifts overall hit-rate
+    from 0.91 to 1.00 and the worst cell (~16 px text on a 2048 canvas) from
+    0.06 to 1.00.
+
+This needs the detector model (downloaded on first use) and a font that covers
+all the scripts (macOS "Arial Unicode"; on Linux install a Noto super-font).
+No GPU. Run:
+
+    uv run python scripts/text_detection_benchmark.py
+"""
+
+from __future__ import annotations
+
+import logging
+import sys
+from collections import defaultdict
+from pathlib import Path
+from typing import Any
+
+import cv2
+import numpy as np
+from PIL import Image, ImageDraw, ImageFont
+from rich.console import Console
+
+from remove_ai_watermarks import text_protector as tp
+
+log = logging.getLogger(__name__)
+console = Console()
+
+# A single font covering every tested script isolates "language" from "font".
+_FONT_CANDIDATES = [
+    "/System/Library/Fonts/Supplemental/Arial Unicode.ttf",
+    "/Library/Fonts/Arial Unicode.ttf",
+    "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc",
+    "/usr/share/fonts/truetype/unifont/unifont.ttf",
+]
+SCRIPTS = {
+    "Latin": "Generated by AI",
+    "Cyrillic": "Сгенерировано ИИ",
+    "CJK": "豆包AI生成内容",
+    "Hangul": "AI로 생성됨",
+    "Arabic": "أنشئ بالذكاء",
+    "Digits": "0123456789",
+}
+FONT_SIZES = [16, 24, 32, 48, 64]
+CANVASES = [1024, 2048]
+PLACEMENTS = [(0.08, 0.15), (0.30, 0.55), (0.10, 0.82)]
+BG_COLORS = [(35, 40, 60), (210, 205, 200)]
+
+
+def _find_font() -> str:
+    for path in _FONT_CANDIDATES:
+        if Path(path).exists():
+            return path
+    raise SystemExit(
+        "No multi-script font found. Install one (macOS ships 'Arial Unicode'; "
+        "on Linux: a Noto CJK/super font) and add its path to _FONT_CANDIDATES."
+    )
+
+
+def _render(
+    font_path: str,
+    canvas: int,
+    text: str,
+    font_size: int,
+    place: tuple[float, float],
+    bg: tuple[int, int, int],
+) -> tuple[Image.Image, tuple[int, int, int, int]]:
+    img = Image.new("RGB", (canvas, canvas), bg)
+    draw = ImageDraw.Draw(img)
+    font = ImageFont.truetype(font_path, font_size)
+    x, y = int(place[0] * canvas), int(place[1] * canvas)
+    fg = (245, 245, 245) if sum(bg) < 360 else (20, 20, 20)
+    draw.text((x, y), text, font=font, fill=fg)
+    return img, draw.textbbox((x, y), text, font=font)
+
+
+def _coverage(boxes: list[Any], bbox: tuple[int, int, int, int], h: int, w: int) -> float | None:
+    gt = np.zeros((h, w), np.uint8)
+    cv2.rectangle(gt, (bbox[0], bbox[1]), (bbox[2], bbox[3]), 1, -1)
+    area = int(gt.sum())
+    if area == 0:
+        return None
+    det = np.zeros((h, w), np.uint8)
+    if boxes:
+        cv2.fillPoly(det, [np.asarray(b, np.int32) for b in boxes], 1)
+    return int((gt & det).sum()) / area
+
+
+def _hitrate(values: list[float], thr: float = 0.5) -> float:
+    return sum(c >= thr for c in values) / len(values) if values else float("nan")
+
+
+def main() -> int:
+    logging.basicConfig(level=logging.WARNING)
+    if not tp.is_available():
+        raise SystemExit("text detector unavailable (need opencv with cv2.dnn.TextDetectionModel_DB)")
+    font_path = _find_font()
+    detector = tp.TextProtector()
+
+    by_script_size: dict[tuple[str, int], list[float]] = defaultdict(list)
+    by_size_canvas: dict[tuple[int, int], list[float]] = defaultdict(list)
+    by_script: dict[str, list[float]] = defaultdict(list)
+
+    for canvas in CANVASES:
+        for script, text in SCRIPTS.items():
+            for font_size in FONT_SIZES:
+                for idx, place in enumerate(PLACEMENTS):
+                    img, bbox = _render(font_path, canvas, text, font_size, place, BG_COLORS[idx % len(BG_COLORS)])
+                    bgr = cv2.cvtColor(np.array(img), cv2.COLOR_RGB2BGR)
+                    cov = _coverage(detector.detect_text_boxes(bgr), bbox, canvas, canvas)
+                    if cov is None:
+                        continue
+                    by_script_size[(script, font_size)].append(cov)
+                    by_size_canvas[(font_size, canvas)].append(cov)
+                    by_script[script].append(cov)
+
+    console.print("=== hit-rate (coverage>=0.5) by script x font-size ===")
+    console.print("script".ljust(10) + "".join(f"{fs:>7}" for fs in FONT_SIZES))
+    for script in SCRIPTS:
+        console.print(
+            script.ljust(10) + "".join(f"{_hitrate(by_script_size[(script, fs)]):>7.2f}" for fs in FONT_SIZES)
+        )
+
+    console.print("\n=== hit-rate by font-size x canvas (the downscale effect) ===")
+    console.print("size".ljust(8) + "".join(f"{c:>8}" for c in CANVASES))
+    for fs in FONT_SIZES:
+        console.print(str(fs).ljust(8) + "".join(f"{_hitrate(by_size_canvas[(fs, c)]):>8.2f}" for c in CANVASES))
+
+    overall = _hitrate([c for vals in by_script.values() for c in vals])
+    console.print(f"\nOVERALL hit-rate: {overall:.2f}  (detector max long side = {tp._DET_MAX_LONG_SIDE})")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())
@@ -1,3 +1,3 @@
 """Remove-AI-Watermarks: Unified tool for removing visible and invisible AI watermarks."""

-__version__ = "0.6.12"
+__version__ = "0.7.0"
@@ -20,12 +20,12 @@ from rich.panel import Panel
 from rich.progress import BarColumn, Progress, SpinnerColumn, TextColumn, TimeElapsedColumn
 from rich.table import Table

-from remove_ai_watermarks import __version__
+from remove_ai_watermarks import __version__, watermark_registry

 if TYPE_CHECKING:
    from numpy.typing import NDArray

-    from remove_ai_watermarks.gemini_engine import DetectionResult, GeminiEngine
+    from remove_ai_watermarks.gemini_engine import DetectionResult

 console = Console()

@@ -101,15 +101,15 @@ def _write_bgr_with_alpha(
    path: Path,
    bgr: NDArray[Any],
    alpha: NDArray[Any] | None,
-    clear_region: tuple[int, int, int, int] | None = None,
-    pad: int = 6,
 ) -> None:
    """Write BGR (with optional alpha) to ``path``.

-    When ``alpha`` is provided and the output extension supports it, writes a
-    4-channel image. If ``clear_region`` is given as ``(x, y, w, h)``, alpha is
-    forced to 0 inside that bbox (expanded by ``pad`` px) so the watermark area
-    becomes fully transparent in the saved file.
+    When ``alpha`` is provided and the output extension supports it, the original
+    alpha plane is rejoined unchanged. The watermark region is NOT made
+    transparent: reverse-alpha (and inpaint) recover real pixels there, so
+    zeroing alpha would punch a transparent hole that renders as a white box on
+    any non-transparent viewer (issue #30). Preserving the input alpha keeps
+    genuinely transparent backgrounds intact without inventing new holes.
    """
    import numpy as np

@@ -119,86 +119,10 @@ def _write_bgr_with_alpha(
        image_io.imwrite(path, bgr)
        return

-    alpha_out = alpha
-    if clear_region is not None:
-        alpha_out = alpha.copy()
-        x, y, w, h = clear_region
-        height, width = alpha.shape[:2]
-        x0, y0 = max(0, x - pad), max(0, y - pad)
-        x1, y1 = min(width, x + w + pad), min(height, y + h + pad)
-        if x1 > x0 and y1 > y0:
-            alpha_out[y0:y1, x0:x1] = 0
-
-    bgra = np.dstack([bgr, alpha_out])
+    bgra = np.dstack([bgr, alpha])
    image_io.imwrite(path, bgra)


-def _run_doubao_if_selected(
-    ctx: click.Context,
-    image: NDArray[Any],
-    alpha: NDArray[Any] | None,
-    output: Path,
-    mark: str,
-    gemini_engine: GeminiEngine,
-    detect: bool,
-    detect_threshold: float,
-    inpaint_method: str,
-    strip_metadata: bool,
-) -> bool:
-    """Run the Doubao text-strip removal path when it is the selected mark.
-
-    Returns True when this path handled the image (caller should stop). In
-    ``auto`` mode the Doubao detector competes with the Gemini detector and wins
-    only when it is both positive and at least as confident.
-    """
-    from remove_ai_watermarks.doubao_engine import DoubaoEngine
-
-    doubao = DoubaoEngine()
-    d_det = doubao.detect(image)
-
-    if mark == "auto":
-        g_det = gemini_engine.detect_watermark(image)
-        use_doubao = d_det.detected and d_det.confidence >= g_det.confidence
-        console.print(
-            f"  [dim]Mark auto:[/] gemini={g_det.confidence:.2f} doubao={d_det.confidence:.2f} "
-            f"-> {'doubao' if use_doubao else 'gemini'}"
-        )
-    else:
-        use_doubao = mark == "doubao"
-
-    if not use_doubao:
-        return False
-
-    if detect and not d_det.detected and d_det.confidence < detect_threshold:
-        console.print(
-            f"  [yellow]⚠[/] Doubao mark not detected  [dim](coverage {d_det.coverage:.1%}). "
-            f"Use --no-detect to force.[/]"
-        )
-        raise SystemExit(0)
-
-    method: Literal["telea", "ns"] = "ns" if inpaint_method == "ns" else "telea"
-    t0 = time.monotonic()
-    with console.status("[cyan]Removing Doubao watermark…[/]"):
-        result = doubao.remove_watermark(image, inpaint_method=method)
-    elapsed = time.monotonic() - t0
-
-    output.parent.mkdir(parents=True, exist_ok=True)
-    _write_bgr_with_alpha(output, result, alpha, clear_region=d_det.region)
-
-    if strip_metadata:
-        try:
-            from remove_ai_watermarks.metadata import remove_ai_metadata
-
-            remove_ai_metadata(output, output)
-        except Exception as e:
-            if ctx.obj.get("verbose"):
-                console.print(f"  [yellow]⚠[/] Failed to strip metadata: {e}")
-
-    size_kb = output.stat().st_size / 1024
-    console.print(f"  [green]✓[/] Doubao mark removed → {output}  [dim]({size_kb:.0f} KB, {elapsed:.2f}s)[/]")
-    return True
-
-
 # ── Main group ───────────────────────────────────────────────────────


@@ -238,9 +162,10 @@ def main(ctx: click.Context, verbose: bool) -> None:
@click.option("--detect-threshold", type=float, default=0.25, help="Detection confidence threshold.")
@click.option(
    "--mark",
-    type=click.Choice(["auto", "gemini", "doubao"]),
+    type=click.Choice(["auto", *watermark_registry.mark_keys()]),
    default="auto",
-    help="Which visible mark to target. auto picks the stronger of the two detectors.",
+    help="Which known visible mark to target (auto picks the strongest detected). "
+    "All marks are removed by exact reverse-alpha against a captured alpha map.",
 )
@click.option("--strip-metadata/--keep-metadata", default=True, help="Strip AI metadata from output.")
@click.pass_context
@@ -256,13 +181,14 @@ def cmd_visible(
    mark: str,
    strip_metadata: bool,
 ) -> None:
-    """Remove a visible AI watermark from an image.
+    """Remove a known visible AI watermark from an image.

-    Targets the Gemini sparkle logo (reverse alpha blending) or the Doubao
-    "豆包AI生成" text strip (locate -> mask -> inpaint). Fast, deterministic,
-    offline. ``--mark auto`` picks whichever detector fires stronger.
+    Finds a known mark in its usual place (Gemini sparkle / Doubao text) via the
+    watermark registry and removes it by exact reverse-alpha against a captured
+    alpha map -- recovering the true pixels, not an inpaint guess. ``--mark auto``
+    picks the strongest detected mark. For arbitrary logos/objects, use ``erase``.
    """
-    from remove_ai_watermarks.gemini_engine import GeminiEngine
+    from remove_ai_watermarks import watermark_registry as registry

    _banner()
    source = _validate_image(source)
@@ -270,8 +196,6 @@ def cmd_visible(
    if output is None:
        output = source.with_stem(source.stem + "_clean")

-    engine = GeminiEngine()
-
    # Load image (preserving any alpha channel separately)
    image, alpha = _read_bgr_and_alpha(source)
    if image is None:
@@ -281,50 +205,49 @@ def cmd_visible(
    h, w = image.shape[:2]
    console.print(f"  [dim]Input:[/]  {source.name}  ({w}x{h})")

-    # Resolve which visible mark to target, then run the Doubao path if chosen.
-    if _run_doubao_if_selected(
-        ctx, image, alpha, output, mark, engine, detect, detect_threshold, inpaint_method, strip_metadata
-    ):
-        return
-
-    # Detection (we always detect softly, to find dynamic region for inpainting)
-    with console.status("[cyan]Detecting watermark…[/]"):
-        det = engine.detect_watermark(image)
-
-    if detect:
-        if det.detected:
-            console.print(
-                f"  [green]✓[/] Watermark detected  "
-                f"[dim](confidence: {det.confidence:.1%}, "
-                f"spatial: {det.spatial_score:.3f}, "
-                f"gradient: {det.gradient_score:.3f})[/]"
-            )
-        else:
-            console.print(f"  [yellow]⚠[/] Watermark not detected  [dim](confidence: {det.confidence:.1%})[/]")
-            if det.confidence < detect_threshold:
-                console.print("  [dim]Skipping. Use --no-detect to force removal.[/]")
+    # Resolve the target mark from the known-watermark registry. ``auto`` scans
+    # every in-auto mark in its usual place and picks the strongest; an explicit
+    # ``--mark <key>`` targets that one (the user asserts its presence).
+    if mark == "auto":
+        best = registry.best_auto_mark(image)
+        if best is None:
+            console.print("  [yellow]⚠[/] No known visible mark detected (gemini / doubao).")
+            if detect:
+                console.print("  [dim]Skipping. Use --mark <name> --no-detect to force.[/]")
                raise SystemExit(0)
+            target = "gemini"  # forced (no-detect): fall back to the default mark
+        else:
+            target = best.key
+            console.print(f"  [dim]Mark auto:[/] {best.label}  [dim]({best.location}, conf {best.confidence:.2f})[/]")
+    else:
+        target = mark

-    # Removal
+    chosen = registry.get_mark(target)
+    det = chosen.detect(image)
+    if detect and not det.detected:
+        console.print(
+            f"  [yellow]⚠[/] {chosen.label} not detected  "
+            f"[dim](conf {det.confidence:.2f}). Use --no-detect to force.[/]"
+        )
+        raise SystemExit(0)
+    if det.detected:
+        console.print(f"  [green]✓[/] {chosen.label} detected  [dim]({chosen.location}, conf {det.confidence:.2f})[/]")
+
+    method: Literal["telea", "ns"] = "ns" if inpaint_method == "ns" else "telea"
    t0 = time.monotonic()
-    region: tuple[int, int, int, int] | None = None
-    with console.status("[cyan]Removing watermark…[/]"):
-        result = engine.remove_watermark(image)
-
-        if inpaint:
-            region = _watermark_region(det, w, h)
-            result = engine.inpaint_residual(
-                result,
-                region,
-                strength=inpaint_strength,
-                method=inpaint_method,
-            )
-
+    with console.status(f"[cyan]Removing {chosen.label}… ({chosen.recovery})[/]"):
+        result, _ = chosen.remove(
+            image,
+            inpaint_method=method,
+            inpaint=inpaint,
+            inpaint_strength=inpaint_strength,
+            force=not detect,
+        )
    elapsed = time.monotonic() - t0

-    # Save (preserves transparency by clearing alpha in the watermark region)
+    # Save (rejoins the original alpha plane unchanged)
    output.parent.mkdir(parents=True, exist_ok=True)
-    _write_bgr_with_alpha(output, result, alpha, clear_region=region)
+    _write_bgr_with_alpha(output, result, alpha)

    # Strip metadata
    if strip_metadata:
@@ -416,8 +339,7 @@ def cmd_erase(
    elapsed = time.monotonic() - t0

    output.parent.mkdir(parents=True, exist_ok=True)
-    clear = boxes[0] if len(boxes) == 1 else None
-    _write_bgr_with_alpha(output, result, alpha, clear_region=clear)
+    _write_bgr_with_alpha(output, result, alpha)

    if strip_metadata:
        try:
@@ -448,7 +370,12 @@ def cmd_erase(
    default="default",
    help="Pipeline profile (default=SDXL, ctrlregen=CtrlRegen).",
 )
-@click.option("--device", type=click.Choice(["auto", "cpu", "mps", "cuda"]), default="auto", help="Inference device.")
+@click.option(
+    "--device",
+    type=click.Choice(["auto", "cpu", "mps", "cuda", "xpu"]),
+    default="auto",
+    help="Inference device.",
+)
@click.option("--seed", type=int, default=None, help="Random seed for reproducibility.")
@click.option("--hf-token", type=str, default=None, help="HuggingFace API token.")
@click.option(
@@ -675,7 +602,12 @@ def cmd_identify(ctx: click.Context, source: Path, no_visible: bool, as_json: bo
    help="Pipeline profile (default=SDXL, ctrlregen=CtrlRegen).",
 )
@click.option("--model", type=str, default=None, help="HuggingFace model ID for invisible removal.")
-@click.option("--device", type=click.Choice(["auto", "cpu", "mps", "cuda"]), default="auto", help="Inference device.")
+@click.option(
+    "--device",
+    type=click.Choice(["auto", "cpu", "mps", "cuda", "xpu"]),
+    default="auto",
+    help="Inference device.",
+)
@click.option("--seed", type=int, default=None, help="Random seed for reproducibility.")
@click.option("--hf-token", type=str, default=None, help="HuggingFace API token.")
@click.option(
@@ -752,7 +684,6 @@ def cmd_all(
        h, w = image.shape[:2]
        console.print(f"    [dim]Input:[/] {source.name}  ({w}x{h})")

-        region: tuple[int, int, int, int] | None = None
        with console.status("[cyan]Removing visible watermark…[/]"):
            det = engine.detect_watermark(image)
            if det.detected:
@@ -766,7 +697,7 @@ def cmd_all(
                console.print("    [dim]Skipped (no visible watermark detected)[/]")

        # Save to temp file for invisible engine input (preserve alpha if present)
-        _write_bgr_with_alpha(tmp_path, result, alpha, clear_region=region)
+        _write_bgr_with_alpha(tmp_path, result, alpha)

        # ── Step 2: Invisible watermark ──────────────────────────────
        console.print("\n  [bold cyan]② Invisible watermark removal[/]")
@@ -818,14 +749,14 @@ def cmd_all(

        # ── Write final result ────────────────────────────────────────
        # The invisible step (and downstream cv2.IMREAD_COLOR paths) drops alpha,
-        # so re-attach the original alpha (with the watermark region cleared)
-        # when writing the final output for transparent formats.
+        # so re-attach the original alpha plane unchanged when writing the final
+        # output for transparent formats.
        output.parent.mkdir(parents=True, exist_ok=True)
        final_bgr, _ = _read_bgr_and_alpha(tmp_path)
        if final_bgr is None:
            console.print(f"[red]Error:[/] Failed to read intermediate file: {tmp_path}")
            raise SystemExit(1)
-        _write_bgr_with_alpha(output, final_bgr, alpha, clear_region=region)
+        _write_bgr_with_alpha(output, final_bgr, alpha)

    finally:
        # Clean up temp file if it still exists
@@ -865,7 +796,6 @@ def _process_batch_image(
        ValueError: If the image cannot be opened.
    """
    saved_alpha: NDArray[Any] | None = None
-    saved_region: tuple[int, int, int, int] | None = None

    if mode in ("visible", "all"):
        from remove_ai_watermarks.gemini_engine import GeminiEngine
@@ -880,7 +810,6 @@ def _process_batch_image(
        if image is None:
            raise ValueError("Failed to read image")

-        region: tuple[int, int, int, int] | None = None
        det = engine.detect_watermark(image)
        if det.detected:
            result = engine.remove_watermark(image)
@@ -891,9 +820,8 @@ def _process_batch_image(
        else:
            result = image.copy()

-        _write_bgr_with_alpha(out_path, result, alpha, clear_region=region)
+        _write_bgr_with_alpha(out_path, result, alpha)
        saved_alpha = alpha
-        saved_region = region

    if mode in ("invisible", "all"):
        from remove_ai_watermarks.invisible_engine import (
@@ -930,7 +858,7 @@ def _process_batch_image(
    if mode == "all" and saved_alpha is not None:
        final_bgr, _ = _read_bgr_and_alpha(out_path)
        if final_bgr is not None:
-            _write_bgr_with_alpha(out_path, final_bgr, saved_alpha, clear_region=saved_region)
+            _write_bgr_with_alpha(out_path, final_bgr, saved_alpha)


@main.command("batch")
@@ -957,7 +885,12 @@ def _process_batch_image(
    default="default",
    help="Pipeline profile (default=SDXL, ctrlregen=CtrlRegen).",
 )
-@click.option("--device", type=click.Choice(["auto", "cpu", "mps", "cuda"]), default="auto", help="Inference device.")
+@click.option(
+    "--device",
+    type=click.Choice(["auto", "cpu", "mps", "cuda", "xpu"]),
+    default="auto",
+    help="Inference device.",
+)
@click.option("--seed", type=int, default=None, help="Random seed for reproducibility.")
@click.option("--hf-token", type=str, default=None, help="HuggingFace API token.")
@click.option(
@@ -1,29 +1,24 @@
 """Doubao visible watermark removal engine.

 Doubao (ByteDance) stamps every generated image with a visible "豆包AI生成"
-(Doubao AI generated) text strip in the bottom-right corner. This is the
-explicit AIGC label mandated by China's TC260 standard, rendered as a
-near-white / light-gray, low-saturation text overlay.
+(Doubao AI generated) text strip in the bottom-right corner -- the explicit AIGC
+label mandated by China's TC260 standard, a near-white semi-transparent overlay.

-Unlike the Gemini sparkle (a fixed square logo removed by reverse alpha
-blending against a captured alpha map), the Doubao mark is a text strip whose
-exact alpha map we do not yet have. This engine therefore removes it by:
+Like the Gemini sparkle, it is a fixed overlay, so it is removed by **exact
+reverse-alpha blending** against a captured alpha map (``remove_watermark_reverse_alpha``):
+``original = (wm - a*logo)/(1-a)`` -- recovering the true pixels, not an inpaint
+guess. The alpha map + logo colour were solved from black+gray Doubao captures
+(see data/doubao_capture/ and the reverse-alpha section below) and bundled as
+``assets/doubao_alpha.png``.

-    locate -> mask -> inpaint
+Detection (``detect``) is reverse-alpha-consistent: it matches that same alpha
+glyph silhouette against the corner via normalized correlation, so it keys on
+the actual "豆包AI生成" shape rather than coverage/structure heuristics.

-1. Locate: the mark scales with image WIDTH and sits in the bottom-right at a
-   fixed margin, so we anchor a generous box there (geometry only -- no bundled
-   template). Constants below are derived from measured Doubao output.
-2. Mask: within the box, extract the light, low-saturation glyph pixels with a
-   polarity-aware rule (the mark is brighter than dark backgrounds and a
-   distinct off-white gray against light backgrounds).
-3. Inpaint: cv2 inpainting (TELEA / NS) reconstructs the covered pixels.
-
-This is fast, offline, deterministic, and needs no GPU. A future upgrade path
-is per-pixel reverse alpha blending once a Doubao alpha map is captured on a
-controlled black background (see data/doubao_capture/), which would recover the
-true pixels instead of hallucinating them -- the same approach as the Gemini
-engine.
+``locate`` (geometry box, scales with image WIDTH) and ``extract_mask`` (the
+candidate glyph mask the detector correlates) remain; there is no inpaint-based
+removal here -- arbitrary-region inpainting lives in ``region_eraser`` / the
+``erase`` command. Fast, offline, no GPU.
 """

 # cv2/numpy boundary: third-party libs ship no usable element types; relax the
@@ -33,7 +28,7 @@ from __future__ import annotations

 import logging
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, Any, Literal
+from typing import TYPE_CHECKING, Any

 import cv2
 import numpy as np
@@ -66,17 +61,63 @@ MAX_SATURATION = 55  # max channel spread to count a pixel as "grayish"
 LOGO_MIN_LUMA = 150  # glyphs are at least this bright in absolute terms
 TOPHAT_DELTA = 12  # glyph must exceed the local background by this many levels

-# Detection: a genuine label fills a meaningful fraction of the box. Measured
-# coverage is >=0.20 on real Doubao outputs; random/textured corners stay <=0.06
-# on large images but can spike to ~0.15 on tiny ones (small box -> high variance),
-# so the threshold sits above that spike and below the real-mark floor.
-DETECT_MIN_COVERAGE = 0.16
+# Detection is reverse-alpha-consistent: the mark is recognized by matching the
+# bundled alpha-template glyph silhouette (assets/doubao_alpha.png -- the exact
+# shape we invert) against the extracted candidate mask via zero-mean normalized
+# correlation (cv2 TM_CCOEFF_NORMED). It keys on the actual "豆包AI生成" glyph
+# SHAPE, not on coverage/structure heuristics, so a merely-textured corner does
+# not fire (the old coverage detector false-positived on ~28% of images; #23).
+# Corpus-tuned: real marks score median ~0.61, arbitrary corners <=0.17 (p99);
+# threshold 0.4 -> false positives 7/1243 (0.6%). A small coverage floor skips
+# the template match on a near-empty candidate box.
+DETECT_MIN_COVERAGE = 0.04
+DETECT_NCC_THRESHOLD = 0.4

-# Safety: a text strip fills a modest slice of the (generous) box. When the box
-# is over a dense-text / document background the mask explodes and cv2 inpainting
-# would smear the real content. Above this coverage we refuse to inpaint and
-# leave the image untouched -- that hard case needs the neural path, not a guess.
-MAX_INPAINT_COVERAGE = 0.50
+# ── Reverse-alpha (exact recovery, Gemini-style) ─────────────────────
+# The Doubao mark is a fixed semi-transparent white overlay, so given its alpha
+# map the original pixels are recovered exactly: original = (wm - a*logo)/(1-a).
+# The alpha map + logo colour were solved from black+gray Doubao captures on a
+# controlled background (data/doubao_capture/): on black, captured = a*logo, and
+# the black/gray pair solves a per-pixel WITHOUT assuming the logo colour. The
+# bundled asset (assets/doubao_alpha.png) is the alpha template (a*255) at the
+# captured width. The mark scales with image WIDTH, but a pure width-scale is
+# only sub-pixel-accurate at the captured width and ghosts elsewhere, so removal
+# does NOT trust fixed geometry: `_aligned_alpha_map` registers the template to
+# the actual mark by a TM_CCOEFF_NORMED scale+position search, which makes the
+# single capture work at any resolution (verified clean on 1773x2364). Verified
+# 2026-05-29: white-capture cross-check -> mark vanishes to a flat fill; clean on
+# doubao-1.png (2048) and the 3:4 portrait corpus size.
+_ALPHA_NATIVE_WIDTH = 2048
+_ALPHA_LOGO_BGR: tuple[float, float, float] = (252.0, 255.0, 255.0)
+_ALPHA_WIDTH_FRAC = 0.1572  # glyph width / image width -- the alignment scale seed
+_ALPHA_HEIGHT_FRAC = 0.0347
+# Margins (of image WIDTH) of the captured mark -- the geometry record / where to
+# seed; alignment refines the actual position, so these are not load-bearing.
+_ALPHA_MARGIN_RIGHT_FRAC = 0.0166
+_ALPHA_MARGIN_BOTTOM_FRAC = 0.0195
+# Alignment scale search (np.linspace args) around the width-scaled glyph size.
+_ALPHA_ALIGN_SEARCH = (0.88, 1.12, 13)
+# At (near) the captured width the fixed geometry is pixel-exact, so we use it
+# directly there -- NCC alignment is integer-pixel and would land ~1px off,
+# degrading the otherwise-exact native recovery. Off this band, alignment wins.
+_ALPHA_NATIVE_BAND = 0.03
+_alpha_template_cache: NDArray[Any] | None = None
+
+
+def _alpha_template() -> NDArray[Any] | None:
+    """Lazily load the bundled Doubao alpha template (float [0,1]), or None."""
+    global _alpha_template_cache
+    if _alpha_template_cache is None:
+        from pathlib import Path
+
+        from remove_ai_watermarks import image_io
+
+        path = Path(__file__).parent / "assets" / "doubao_alpha.png"
+        img = image_io.imread(str(path), cv2.IMREAD_GRAYSCALE)
+        if img is None:
+            return None
+        _alpha_template_cache = img.astype(np.float32) / 255.0
+    return _alpha_template_cache


@dataclass(frozen=True)
@@ -104,6 +145,39 @@ class DoubaoDetection:
    coverage: float = 0.0  # fraction of the box occupied by glyph pixels


+_silhouette_cache: NDArray[Any] | None = None
+
+
+def _glyph_silhouette() -> NDArray[Any] | None:
+    """Binary "豆包AI生成" silhouette (255 = glyph) from the bundled alpha map,
+    used as the detection template. None if the alpha asset is missing."""
+    global _silhouette_cache
+    if _silhouette_cache is None:
+        at = _alpha_template()
+        if at is None:
+            return None
+        _silhouette_cache = (at > 0.15).astype(np.uint8) * 255
+    return _silhouette_cache
+
+
+def _template_match_score(box_mask: NDArray[Any], image_width: int) -> float:
+    """Zero-mean normalized correlation of the alpha-template glyph silhouette
+    (scaled to the mark's expected size) against the candidate ``box_mask``.
+
+    TM_CCOEFF_NORMED keys on glyph SHAPE, not coverage, so a dense textured
+    corner does not score highly -- only the actual "豆包AI生成" shape does.
+    """
+    sil = _glyph_silhouette()
+    if sil is None or box_mask.size == 0:
+        return 0.0
+    gw = min(box_mask.shape[1] - 1, max(8, int(_ALPHA_WIDTH_FRAC * image_width)))
+    gh = min(box_mask.shape[0] - 1, max(4, int(_ALPHA_HEIGHT_FRAC * image_width)))
+    if gw < 8 or gh < 4:
+        return 0.0
+    template = cv2.resize(sil, (gw, gh), interpolation=cv2.INTER_NEAREST)
+    return float(cv2.matchTemplate(box_mask, template, cv2.TM_CCOEFF_NORMED).max())
+
+
 class DoubaoEngine:
    """Remove the visible Doubao "豆包AI生成" watermark (locate -> mask -> inpaint)."""

@@ -176,10 +250,12 @@ class DoubaoEngine:
    # ── Detect ────────────────────────────────────────────────────────

    def detect(self, image: NDArray[Any]) -> DoubaoDetection:
-        """Detect the visible Doubao mark by glyph coverage in the corner box.
+        """Detect the visible Doubao mark by matching the alpha-template glyph
+        silhouette against the corner candidate (TM_CCOEFF_NORMED).

-        Heuristic: a genuine label fills a meaningful fraction of the box with
-        text-like glyph pixels. Coverage maps to a confidence score.
+        Keys on the "豆包AI生成" SHAPE, not coverage, so a textured corner does
+        not fire. ``confidence`` is the correlation score; ``detected`` is it
+        clearing ``DETECT_NCC_THRESHOLD``.
        """
        det = DoubaoDetection()
        if image is None or image.size == 0:
@@ -191,53 +267,113 @@ class DoubaoEngine:
        coverage = float((box > 0).sum()) / float(max(1, bw * bh))
        det.region = loc.bbox
        det.coverage = coverage
-        # Map coverage to a 0-1 confidence: ~0.06 (noise floor) -> 0, ~0.26 -> 1.
-        det.confidence = float(max(0.0, min(1.0, (coverage - 0.06) / 0.20)))
-        det.detected = coverage >= DETECT_MIN_COVERAGE
-        logger.debug("Doubao detect: coverage=%.3f conf=%.3f", coverage, det.confidence)
+        if coverage >= DETECT_MIN_COVERAGE:
+            score = _template_match_score(box, image.shape[1])
+            det.confidence = score
+            det.detected = score >= DETECT_NCC_THRESHOLD
+            logger.debug("Doubao detect: coverage=%.3f ncc=%.2f detected=%s", coverage, score, det.detected)
        return det

-    # ── Remove ────────────────────────────────────────────────────────
+    # ── Reverse-alpha (exact recovery) ────────────────────────────────

-    def remove_watermark(
-        self,
-        image: NDArray[Any],
-        *,
-        inpaint_method: Literal["telea", "ns"] = "telea",
-        inpaint_radius: int = 6,
-        dilate: int = 3,
-    ) -> NDArray[Any]:
-        """Remove the visible Doubao watermark by inpainting the glyph mask.
+    def reverse_alpha_available(self, image: NDArray[Any]) -> bool:
+        """True if the bundled alpha map is loadable. Sub-pixel NCC alignment
+        (see ``_aligned_alpha_map``) places it on the actual mark at ANY
+        resolution, so there is no width gate -- the caller still gates on
+        ``detect`` so a clean corner is never touched."""
+        return image is not None and image.size > 0 and _alpha_template() is not None

-        Returns an unmodified copy when no glyph pixels are found (so we never
-        smear a clean corner). ``dilate`` grows the mask to cover anti-aliased
-        glyph edges before inpainting.
-        """
-        if image is None or image.size == 0:
-            return image
+    def _fixed_alpha_map(self, image: NDArray[Any]) -> tuple[NDArray[Any], tuple[int, int, int, int]] | None:
+        """Place the template by fixed width-relative geometry -- pixel-exact at
+        the captured width (used there instead of integer-pixel NCC alignment)."""
+        at = _alpha_template()
+        if at is None:
+            return None
+        h, w = image.shape[:2]
+        gw, gh = max(1, int(_ALPHA_WIDTH_FRAC * w)), max(1, int(_ALPHA_HEIGHT_FRAC * w))
+        ax = max(0, w - int(_ALPHA_MARGIN_RIGHT_FRAC * w) - gw)
+        ay = max(0, h - int(_ALPHA_MARGIN_BOTTOM_FRAC * w) - gh)
+        amap = np.zeros((h, w), np.float32)
+        amap[ay : ay + gh, ax : ax + gw] = cv2.resize(at, (gw, gh), interpolation=cv2.INTER_LINEAR)
+        return amap, (ax, ay, gw, gh)
+
+    def _aligned_alpha_map(self, image: NDArray[Any]) -> tuple[NDArray[Any], tuple[int, int, int, int]] | None:
+        """Build a full-image alpha map with the captured template registered to
+        the actual mark via a TM_CCOEFF_NORMED scale + position search -- so the
+        single capture works off the captured width (a pure width-scale ghosts).
+        Returns ``(alpha_map, glyph_bbox)`` or None."""
+        at = _alpha_template()
+        sil = _glyph_silhouette()
+        if at is None or sil is None:
+            return None
+        h, w = image.shape[:2]
        loc = self.locate(image)
-        mask = self.extract_mask(image, loc)
-        if not mask.any():
-            logger.debug("Doubao remove: no glyph pixels found; returning copy")
+        bx, by, bw, bh = loc.bbox
+        box_mask = self.extract_mask(image, loc)[by : by + bh, bx : bx + bw]
+        expected = _ALPHA_WIDTH_FRAC * w
+        best: tuple[float, int, int, int, int] | None = None
+        for scale in np.linspace(*_ALPHA_ALIGN_SEARCH):
+            gw, gh = int(expected * scale), int(_ALPHA_HEIGHT_FRAC * w * scale)
+            if gw < 8 or gh < 4 or gw >= bw or gh >= bh:
+                continue
+            t = cv2.resize(sil, (gw, gh), interpolation=cv2.INTER_NEAREST)
+            _, score, _, top_left = cv2.minMaxLoc(cv2.matchTemplate(box_mask, t, cv2.TM_CCOEFF_NORMED))
+            if best is None or score > best[0]:
+                best = (score, gw, gh, top_left[0], top_left[1])
+        if best is None:
+            return None
+        _, gw, gh, ox, oy = best
+        ax, ay = bx + ox, by + oy
+        amap = np.zeros((h, w), np.float32)
+        amap[ay : ay + gh, ax : ax + gw] = cv2.resize(at, (gw, gh), interpolation=cv2.INTER_LINEAR)
+        return amap, (ax, ay, gw, gh)
+
+    def _apply_reverse_alpha(self, image: NDArray[Any], amap: NDArray[Any]) -> NDArray[Any]:
+        """Invert the alpha blend with ``amap``: ``original = (wm - a*logo)/(1-a)``."""
+        a3 = np.clip(amap, 0.0, 1.0)[:, :, None]
+        logo = np.array(_ALPHA_LOGO_BGR, np.float32)
+        return np.clip((image.astype(np.float32) - a3 * logo) / np.clip(1.0 - a3, 0.25, 1.0), 0, 255).astype(np.uint8)
+
+    def remove_watermark_reverse_alpha(self, image: NDArray[Any], *, residual_inpaint: bool = True) -> NDArray[Any]:
+        """Recover the original pixels by inverting the alpha blend
+        ``original = (wm - a*logo)/(1-a)``.
+
+        Placement: at (near) the captured width the fixed geometry is pixel-exact,
+        so the recovery is returned UNTOUCHED -- inpainting over exactly-recovered
+        interior pixels only swaps them for a cv2 hallucination (measured worse on
+        textured backgrounds: native error vs true bg 1.6 reverse-alpha-only vs
+        2.6 with full-footprint inpaint). Off-native, NCC alignment registers the
+        template to the real mark; the alignment is only sub-pixel-approximate, so
+        the interior recovery is no longer exact and the seam can re-trip the
+        detector. There we try BOTH placements and keep whichever leaves the least
+        residual mark (on a faint/busy-background mark the NCC peak can wander a
+        few px, where geometry wins; on a clear mark alignment wins) -- no magic
+        threshold, it just picks the better removal -- then a residual inpaint over
+        the glyph footprint cleans the seam (the interior is approximate anyway, so
+        inpaint there costs nothing and reliably clears the mark).
+        Call only when :meth:`reverse_alpha_available` and the mark is detected.
+        """
+        at_native = abs(image.shape[1] / _ALPHA_NATIVE_WIDTH - 1.0) <= _ALPHA_NATIVE_BAND
+        if at_native:
+            amap = self._fixed_alpha_map(image)
+            return self._apply_reverse_alpha(image, amap[0]) if amap is not None else image.copy()
+        maps = [c for c in (self._fixed_alpha_map(image), self._aligned_alpha_map(image)) if c is not None]
+        if not maps:
            return image.copy()
-
-        x, y, bw, bh = loc.bbox
-        coverage = float((mask[y : y + bh, x : x + bw] > 0).sum()) / float(max(1, bw * bh))
-        if coverage > MAX_INPAINT_COVERAGE:
-            logger.warning(
-                "Doubao remove: box coverage %.2f exceeds %.2f (dense-text/document "
-                "background); leaving image untouched to avoid smearing content",
-                coverage,
-                MAX_INPAINT_COVERAGE,
-            )
+        best_out: NDArray[Any] | None = None
+        best_amap: NDArray[Any] | None = None
+        best_residual = float("inf")
+        for amap, _region in maps:
+            out = self._apply_reverse_alpha(image, amap)
+            residual = self.detect(out).confidence
+            if residual < best_residual:
+                best_residual, best_out, best_amap = residual, out, amap
+        if best_out is None or best_amap is None:  # pragma: no cover - maps is non-empty
            return image.copy()
-
-        if dilate > 0:
-            k = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (2 * dilate + 1, 2 * dilate + 1))
-            mask = cv2.dilate(mask, k)
-
-        flag = cv2.INPAINT_TELEA if inpaint_method == "telea" else cv2.INPAINT_NS
-        return cv2.inpaint(image, mask, inpaint_radius, flag)
+        if residual_inpaint:
+            rm = cv2.dilate((best_amap > 0.10).astype(np.uint8) * 255, np.ones((3, 3), np.uint8))
+            best_out = cv2.inpaint(best_out, rm, 3, cv2.INPAINT_TELEA)
+        return best_out


 def load_image_bgr(path: str | Path) -> NDArray[Any]:
@@ -25,14 +25,15 @@ from typing import TYPE_CHECKING
 from remove_ai_watermarks.metadata import (
    AI_METADATA_KEYS,
    AIGC_MARKERS,
-    C2PA_UUID,
    IPTC_AI_FIELD_MARKERS,
    IPTC_AI_MARKERS,
    aigc_label,
+    c2pa_marker_in,
    exif_generator,
    get_ai_metadata,
    huggingface_job,
    iptc_ai_system,
+    samsung_genai,
    scan_head,
    xai_signature,
 )
@@ -65,6 +66,8 @@ _ISSUER_PLATFORM: tuple[tuple[str, str], ...] = (
    ("OpenAI", "OpenAI (ChatGPT / gpt-image / DALL-E / Sora)"),
    ("Google", "Google (Gemini / Imagen)"),
    ("Stability AI", "Stability AI (Stable Image / DreamStudio)"),
+    ("Black Forest Labs", "Black Forest Labs (FLUX)"),
+    ("ByteDance", "ByteDance (Doubao / Jimeng / Volcano Engine)"),
 )

 # PNG-text / EXIF keys that indicate a local diffusion pipeline (vs. a hosted
@@ -95,6 +98,12 @@ _HF_JOB_CAVEAT = (
    "generation) but names neither the model nor the content type, so it is a "
    "medium-confidence signal, not proof the pixels are AI-generated."
 )
+_SAMSUNG_GENAI_CAVEAT = (
+    "Samsung's genAIType marker shows a Galaxy AI editing tool (Generative Edit, "
+    "Sketch to Image, ...) touched the image; it is an undocumented proprietary "
+    "field, so it is a medium-confidence signal of AI editing, not proof the "
+    "whole image is AI-generated."
+)


@dataclass
@@ -151,7 +160,9 @@ def _ai_tools_in(data: bytes) -> list[str]:
 # assert is_ai on their own (the verdict still comes from the digital-source-type:
 # the Pixel sample carries `computationalCapture`, not `trainedAlgorithmicMedia`).
 # Only tokens verified against a real signed file are listed (Leica, Nikon,
-# Truepic, Google Pixel); add Sony/Canon/Samsung/Bria as real samples are captured.
+# Sony, Truepic, Google Pixel); add Canon/Bria as real samples are captured.
+# Samsung Galaxy is an AI-capable editing device, not a pure-capture camera, so
+# it lives in `_SIGNER_C2PA_PLATFORM` below (it must not feed the camera clash).
 _DEVICE_C2PA_PLATFORM: tuple[tuple[bytes, str], ...] = (
    (b"lc_c2pa", "Leica (camera, C2PA capture)"),
    (b"Leica Camera", "Leica (camera, C2PA capture)"),
@@ -177,6 +188,32 @@ def _device_platform(head: bytes) -> str | None:
    return None


+# C2PA signers that are an editing app or AI-capable device rather than a
+# verified-capture camera. Unlike `_DEVICE_C2PA_PLATFORM`, these do NOT feed the
+# camera-vs-AI integrity clash (rule 2 in `_integrity_clashes`): a Galaxy phone
+# legitimately stamps BOTH its device credentials AND a `trainedAlgorithmicMedia`
+# source type on a Generative-Edit image, so treating it as a "genuine camera
+# capture" would false-flag every Galaxy AI edit. They only resolve the platform
+# label; the AI verdict still comes from the digital-source-type / genAIType.
+# Tokens verified against real signed files (2026-05-29):
+#   Samsung Galaxy -- cert org on Galaxy S23 FE / S24 / S25 C2PA JPEGs/PNGs
+#     (distinct from the EXIF "SM-xxxx" model string on ordinary Samsung photos).
+#   com.asus.gallery -- ASUS Gallery claim_generator (a C2PA-signed edit, no AI
+#     source type or genAIType on the samples, so it never asserts is_ai).
+_SIGNER_C2PA_PLATFORM: tuple[tuple[bytes, str], ...] = (
+    (b"Samsung Galaxy", "Samsung Galaxy (C2PA)"),
+    (b"com.asus.gallery", "ASUS Gallery (C2PA signer)"),
+)
+
+
+def _signer_platform(head: bytes) -> str | None:
+    """Map a C2PA editing-app / AI-capable-device signer token to a platform."""
+    for token, platform in _SIGNER_C2PA_PLATFORM:
+        if token in head:
+            return platform
+    return None
+
+
 def _attribute_platform(issuers: list[str], *, is_ai: bool = True) -> str | None:
    """Map a set of C2PA issuer names to a human-readable generating platform.

@@ -353,9 +390,10 @@ def identify(image_path: Path, *, check_visible: bool = True, check_invisible: b
    # neither is a trustworthy "the generator stamped its identity" claim.
    ai_vendor_claims: dict[str, str] = {}
    camera_label = _device_platform(head)
+    signer_label = _signer_platform(head)

    # ── C2PA Content Credentials ────────────────────────────────────
-    has_c2pa = bool(info) or b"c2pa" in head.lower() or C2PA_UUID in head
+    has_c2pa = bool(info) or c2pa_marker_in(head)
    issuers = [info["issuer"]] if info.get("issuer") else _issuers_in(head)
    c2pa_is_ai = "trainedAlgorithmicMedia" in info.get("source_type", "") or any(
        m in head for m in (b"trainedAlgorithmicMedia", b"compositeWithTrainedAlgorithmicMedia")
@@ -370,10 +408,11 @@ def identify(image_path: Path, *, check_visible: bool = True, check_invisible: b
        or (", ".join(tools) if (tools := _ai_tools_in(head)) else None)
    )
    # Platform: a distinctive device/camera token in the manifest wins (it is the
-    # signer/producer), with the issuer byte-scan only as fallback. The issuer
-    # scan alone mis-attributed real samples (Leica->Truepic timestamp authority,
-    # Nikon->Adobe namespace, Pixel->Google Gemini) -- the device scan fixes that.
-    platform = (camera_label or _attribute_platform(issuers, is_ai=c2pa_is_ai)) if has_c2pa else None
+    # signer/producer), then an editing-app/AI-device signer (Samsung Galaxy,
+    # ASUS Gallery), with the issuer byte-scan only as fallback. The issuer scan
+    # alone mis-attributed real samples (Leica->Truepic timestamp authority,
+    # Nikon->Adobe namespace, Pixel->Google Gemini) -- the token scans fix that.
+    platform = (camera_label or signer_label or _attribute_platform(issuers, is_ai=c2pa_is_ai)) if has_c2pa else None
    if has_c2pa:
        detail = ", ".join(filter(None, [", ".join(issuers), generator, info.get("source_type")]))
        signals.append(Signal("c2pa", detail or "C2PA manifest present", "high"))
@@ -484,6 +523,22 @@ def identify(image_path: Path, *, check_visible: bool = True, check_invisible: b
        if platform is None:
            platform = "HuggingFace-hosted job (model not identified)"

+    # ── Samsung Galaxy AI editing marker (genAIType) ─────────────────
+    # Galaxy AI tools stamp a proprietary genAIType in PhotoEditor_Re_Edit_Data.
+    # Medium confidence: it co-occurs with the C2PA trainedAlgorithmicMedia type
+    # on Galaxy files that record one, and is the SOLE AI marker on a Galaxy S24
+    # sample that omits the source type -- so it lifts an otherwise-Unknown
+    # verdict, but the field is undocumented, so it never overrides a high-
+    # confidence signal. The platform is usually already "Samsung Galaxy" via the
+    # signer-token scan; the fallback covers a future file without the cert org.
+    samsung_genai_type = samsung_genai(image_path)
+    if samsung_genai_type is not None:
+        signals.append(Signal("samsung_genai", f"Samsung genAIType={samsung_genai_type}", "medium"))
+        watermarks.append("Samsung Galaxy AI editing marker (genAIType)")
+        caveats.append(_SAMSUNG_GENAI_CAVEAT)
+        if platform is None:
+            platform = "Samsung Galaxy (Galaxy AI editing)"
+
    # ── Open invisible watermark (SD / SDXL / FLUX, dwtDct) ──────────
    # Public decoder, no key -- a definitive embedded signal on pristine files.
    if check_invisible and (scheme := _invisible_watermark(image_path)) is not None:
@@ -527,11 +582,12 @@ def identify(image_path: Path, *, check_visible: bool = True, check_invisible: b

    visible_only = any(s.name == "visible_sparkle" for s in signals) and not ai_from_metadata
    hf_only = bool(hf_job) and not ai_from_metadata
+    samsung_only = samsung_genai_type is not None and not ai_from_metadata

    if ai_from_metadata:
        is_ai: bool | None = True
        confidence = "high"
-    elif visible_only or hf_only:
+    elif visible_only or hf_only or samsung_only:
        is_ai = True
        confidence = "medium"
    else:
@@ -88,7 +88,7 @@ class InvisibleEngine:

        Args:
            model_id: HuggingFace model ID. None = use default for pipeline.
-            device: Device for inference (auto/cpu/mps/cuda). None = auto.
+            device: Device for inference (auto/cpu/mps/cuda/xpu). None = auto.
            pipeline: Pipeline profile. "default" (SDXL base, defeats SynthID
                v2) or "ctrlregen" (CtrlRegen).
            hf_token: HuggingFace API token.
@@ -11,6 +11,7 @@ from __future__ import annotations
 import contextlib
 import logging
 import re
+import struct
 from typing import TYPE_CHECKING, Any

 if TYPE_CHECKING:
@@ -65,6 +66,22 @@ AI_KEYWORDS: tuple[str, ...] = (
 # Reference: https://spec.c2pa.org/specifications/specifications/2.1/specs/C2PA_Specification.html
 C2PA_UUID: bytes = bytes.fromhex("d8fec3d61b0e483c92975828877ec481")

+
+def c2pa_marker_in(data: bytes) -> bool:
+    """True if ``data`` carries a real C2PA manifest marker, not just an
+    incidental 4-byte ``c2pa`` substring.
+
+    A bare ``c2pa`` byte match false-positives on compressed pixel data -- a
+    recompressed PNG IDAT (or any large binary) can contain the bytes ``c2pa``
+    by chance (verified 2026-05-29: 4 cleaned PNGs re-flagged this way after
+    their manifest was correctly stripped). Every real manifest is JUMBF-wrapped
+    (the ``jumb`` box FourCC accompanies the ``c2pa`` content type) or uses the
+    standalone C2PA ``uuid`` box in ISOBMFF, so we require one of those: the
+    joint ``jumb`` + ``c2pa`` match has negligible random-collision probability.
+    """
+    return C2PA_UUID in data or (b"jumb" in data and b"c2pa" in data.lower())
+
+
 # IPTC ``digitalSourceType`` values (IPTC 2025.1) that flag AI provenance.
 # Used by Instagram, Facebook, X (Twitter) to show "Made with AI" labels.
 IPTC_AI_MARKERS: tuple[bytes, ...] = (
@@ -153,15 +170,58 @@ def _is_ai_key(key: str) -> bool:
    return any(kw in key_lower for kw in AI_KEYWORDS)


+# PNG ancillary chunks that can carry provenance metadata (XMP, EXIF, text).
+# Never IDAT -- that is the compressed pixel stream.
+_PNG_META_CHUNKS: frozenset[bytes] = frozenset({b"tEXt", b"iTXt", b"zTXt", b"eXIf", b"iCCP"})
+
+
+def _png_late_metadata(image_path: Path, window: int) -> bytes:
+    """Payloads of PNG metadata chunks that start *beyond* the first ``window``
+    bytes, found by seeking past the (large) ``IDAT`` pixel stream.
+
+    A PNG encoder may append the XMP/EXIF packet after the image data, so a
+    fixed first-``size`` read misses it (e.g. a TC260 AIGC label in an XMP
+    ``iTXt`` chunk at ~2.7 MB). This is the PNG analogue of the ISOBMFF
+    late-box scan in :func:`scan_head`. Returns only chunks past ``window`` so
+    bytes already in the head are not duplicated; empty when there are none.
+    """
+    out = bytearray()
+    try:
+        with open(image_path, "rb") as f:
+            if f.read(8) != b"\x89PNG\r\n\x1a\n":
+                return b""
+            pos = 8
+            while True:
+                f.seek(pos)
+                header = f.read(8)
+                if len(header) < 8:
+                    break
+                (length,) = struct.unpack(">I", header[:4])
+                chunk_type = header[4:8]
+                if chunk_type == b"IEND":
+                    break
+                data_start = pos + 8
+                if chunk_type in _PNG_META_CHUNKS and data_start >= window:
+                    f.seek(data_start)
+                    out += f.read(length)
+                pos = data_start + length + 4  # data + CRC
+    except OSError as exc:
+        logger.debug("PNG late-metadata scan failed on %s: %s", image_path, exc)
+        return b""
+    return bytes(out)
+
+
 def scan_head(image_path: Path, size: int = 1024 * 1024) -> bytes:
-    """First ``size`` bytes of the file, plus -- for ISOBMFF containers -- the
-    payloads of any provenance (``uuid`` / ``jumb``) boxes found beyond that
-    window by seeking past large boxes like ``mdat``.
+    """First ``size`` bytes of the file, plus the payloads of any provenance
+    metadata found beyond that window: ISOBMFF ``uuid`` / ``jumb`` boxes (seeking
+    past large boxes like ``mdat``) and PNG ``tEXt`` / ``iTXt`` / ``eXIf`` chunks
+    (seeking past ``IDAT``).

    This is the shared input for every C2PA / AIGC / IPTC byte scan. The
-    ISOBMFF extension catches a manifest placed AFTER the media data in a
-    streaming / non-faststart MP4, which a fixed first-MB read would miss. For
-    non-ISOBMFF inputs it is exactly ``f.read(size)`` -- behavior-neutral.
+    extensions catch a manifest or XMP packet placed AFTER the media data -- a
+    non-faststart MP4 manifest, or a PNG XMP packet appended after the pixels --
+    which a fixed first-MB read would miss. For other inputs, and for files that
+    fit within ``size``, it is exactly ``f.read(size)`` -- behavior-neutral.
    """
    with open(image_path, "rb") as f:
        head = f.read(size)
@@ -172,6 +232,10 @@ def scan_head(image_path: Path, size: int = 1024 * 1024) -> bytes:
        region = isobmff.scan_c2pa_region(image_path)
        if region:
            head += region
+    elif head[:8] == b"\x89PNG\r\n\x1a\n" and len(head) == size:
+        # len(head) == size means the file is at least `size` bytes, so metadata
+        # chunks may lie beyond the window; otherwise the whole PNG is in `head`.
+        head += _png_late_metadata(image_path, size)
    return head


@@ -213,9 +277,7 @@ def has_ai_metadata(image_path: Path) -> bool:
    # Binary scan covers C2PA (PNG caBX, JPEG APP11, AVIF/HEIF/JXL uuid boxes)
    # and IPTC AI markers in XMP. First 512KB (plus late ISOBMFF provenance boxes).
    data = scan_head(image_path, 512 * 1024)
-    if b"c2pa" in data.lower() or b"C2PA" in data:
-        return True
-    if C2PA_UUID in data:
+    if c2pa_marker_in(data):
        return True
    if any(marker in data for marker in AIGC_MARKERS):
        return True
@@ -238,17 +300,21 @@ def has_ai_metadata(image_path: Path) -> bool:
 def aigc_label(image_path: Path) -> dict[str, str] | None:
    """Parse a China TC260 AI-labeling block, if present.

-    Two serializations are recognized:
+    Three serializations are recognized:

    - a PNG ``tEXt``/``iTXt`` chunk keyed ``AIGC`` carrying the raw JSON object
-      (as written by Doubao / ByteDance), read via PIL; and
+      (as written by Doubao / ByteDance), read via PIL;
    - an XMP ``<TC260:AIGC>{...}</TC260:AIGC>`` block (HTML-entity encoded text),
-      found by a container-agnostic raw-byte scan (PNG/JPEG/WebP alike).
+      found by a container-agnostic raw-byte scan (PNG/JPEG/WebP alike); and
+    - a raw-JSON ``{"AIGC":{...}}`` block with no namespace, as embedded in JPEG
+      EXIF (UserComment) by some China-served generators, brace-matched from the
+      scan head.

    Returns the decoded JSON (e.g. ``{"Label": "1", "ContentProducer": ...}``)
-    or None. The PNG-chunk key ``AIGC`` is generic, so a JSON object there is
-    accepted only if it carries at least one known TC260 field (``_TC260_FIELDS``);
-    the namespaced XMP element is unambiguous, so any JSON object is accepted.
+    or None. The generic forms (the PNG-chunk key ``AIGC`` and the bare
+    ``{"AIGC":...}`` object) are accepted only if they carry at least one known
+    TC260 field (``_TC260_FIELDS``); the namespaced XMP element is unambiguous,
+    so any JSON object is accepted.
    """
    import html
    import json
@@ -279,12 +345,35 @@ def aigc_label(image_path: Path) -> dict[str, str] | None:
    if isinstance(value, str) and (result := _parse(value, require_tc260_field=True)):
        return result

-    # XMP <TC260:AIGC>{...}</TC260:AIGC> block (namespaced element, unambiguous).
+    # XMP TC260:AIGC, namespaced (unambiguous) in either serialization RDF allows:
+    # an element  <TC260:AIGC>{...}</TC260:AIGC>  or an attribute  TC260:AIGC="{...}"
+    # (the attribute form is what PicWish writes). Both are HTML-entity encoded.
    data = scan_head(image_path)
-    match = re.search(rb"<TC260:AIGC>(.*?)</TC260:AIGC>", data, re.DOTALL)
-    if not match:
-        return None
-    return _parse(html.unescape(match.group(1).decode("utf-8", "replace")), require_tc260_field=False)
+    match = re.search(
+        rb'<TC260:AIGC>(.*?)</TC260:AIGC>|TC260:AIGC\s*=\s*"(.*?)"',
+        data,
+        re.DOTALL,
+    )
+    if match:
+        body = match.group(1) if match.group(1) is not None else match.group(2)
+        return _parse(html.unescape(body.decode("utf-8", "replace")), require_tc260_field=False)
+
+    # Raw-JSON {"AIGC":{...}} block (no namespace), as written into JPEG EXIF
+    # (UserComment) by some China-served generators -- the PNG-chunk and XMP
+    # paths above both miss it. The bytes pre-check keeps the common (no-AIGC)
+    # path off the full-buffer decode; raw_decode then brace-matches the inner
+    # object (respecting nested braces / quoted strings) and `_parse` applies the
+    # same dict coercion + TC260-field gate as the generic PNG-chunk path.
+    if b'"AIGC"' in data:
+        text = data.decode("latin-1")
+        brace = text.find("{", text.find('"AIGC"') + len('"AIGC"'))
+        if brace != -1:
+            try:
+                _, end = json.JSONDecoder().raw_decode(text, brace)
+            except ValueError:
+                return None
+            return _parse(text[brace:end], require_tc260_field=True)
+    return None


 def huggingface_job(image_path: Path) -> str | None:
@@ -310,6 +399,39 @@ def huggingface_job(image_path: Path) -> str | None:
    return None


+# Samsung Galaxy AI editing marker. Galaxy AI tools (Generative Edit, Sketch to
+# Image, Portrait Studio, Drawing Assist, ...) record their re-edit data as a
+# proprietary ``PhotoEditor_Re_Edit_Data`` JSON that carries a ``genAIType``
+# field; a non-zero value flags that a generative-AI tool produced or altered
+# the pixels. The field is undocumented by Samsung (verified 2026-05-29: absent
+# from the C2PA spec and Samsung's public docs/forums), so detection is
+# empirical -- on real Galaxy S23/S24/S25 files it co-occurs with the C2PA
+# ``trainedAlgorithmicMedia`` source type (3/3 of the verified files that record
+# that type), and on a Galaxy S24 sample it is the *only* AI marker (the C2PA
+# source type was absent there). Medium confidence: it signals Galaxy AI editing
+# without proving the whole image is AI-generated. Scoped to the Samsung editor
+# container to avoid matching a stray ``genAIType`` token elsewhere.
+_SAMSUNG_GENAI_RE = re.compile(rb'genAIType"\s*:\s*(-?\d+)')
+_SAMSUNG_EDITOR_MARKER = b"PhotoEditor_Re_Edit_Data"
+
+
+def samsung_genai(image_path: Path) -> int | None:
+    """Return Samsung's non-zero ``genAIType`` value if the image carries the
+    Galaxy AI editing marker, else None.
+
+    See the module note above ``_SAMSUNG_GENAI_RE``: detection is empirical and
+    gated on the ``PhotoEditor_Re_Edit_Data`` container so an incidental
+    ``genAIType`` token cannot false-positive.
+    """
+    head = scan_head(image_path, 512 * 1024)
+    if _SAMSUNG_EDITOR_MARKER not in head:
+        return None
+    m = _SAMSUNG_GENAI_RE.search(head)
+    if m is None:
+        return None
+    return int(m.group(1)) or None
+
+
 def iptc_ai_system(image_path: Path) -> str | None:
    """Return an IPTC 2025.1 AI-disclosure note if the file carries those XMP
    properties, else None.
@@ -360,7 +482,7 @@ def synthid_source(image_path: Path) -> str | None:
    # C2PA manifest where the PNG parser can't reach it. Binary-scan for the
    # same signal: a C2PA manifest from a SynthID-using issuer on AI content.
    data = scan_head(image_path)
-    has_c2pa = b"c2pa" in data.lower() or C2PA_UUID in data
+    has_c2pa = c2pa_marker_in(data)
    # Matches both "trainedAlgorithmicMedia" and "compositeWithTrainedAlgorithmicMedia".
    ai_source = b"trainedAlgorithmicMedia" in data or b"TrainedAlgorithmicMedia" in data
    if not (has_c2pa and ai_source):
@@ -585,6 +707,9 @@ def get_ai_metadata(image_path: Path) -> dict[str, str]:
    # HuggingFace-hosted job marker (hf-job-id PNG text chunk).
    if job := huggingface_job(image_path):
        result.setdefault("huggingface_job", f"HuggingFace-hosted job ({job})")
+    # Samsung Galaxy AI editing marker (genAIType in PhotoEditor_Re_Edit_Data).
+    if (genai := samsung_genai(image_path)) is not None:
+        result.setdefault("samsung_genai", f"Samsung Galaxy AI editing marker (genAIType={genai})")
    return result


@@ -88,6 +88,14 @@ C2PA_ISSUERS = {
    # Stability AI signs C2PA as "Stability AI" (cert org "Stability AI Ltd").
    # Verified on a live Brand Studio (DreamStudio successor) output, 2026-05-24.
    b"Stability AI": "Stability AI",
+    # Black Forest Labs (FLUX) API output: claim_generator_info "Black Forest
+    # Labs API" + a c2pa.ai_generated_content assertion + trainedAlgorithmicMedia.
+    # Verified on a real signed FLUX JPEG, 2026-05-29.
+    b"Black Forest Labs": "Black Forest Labs",
+    # ByteDance's Volcano Engine (Volcengine) signs its AI image output with a
+    # cert from certificate_center@volcengine.com -- the platform behind Doubao /
+    # Jimeng. Verified on two real signed JPEGs, 2026-05-29.
+    b"volcengine": "ByteDance (Volcano Engine)",
 }

 # C2PA issuers whose signed outputs also carry an invisible SynthID pixel
@@ -222,6 +222,19 @@ def get_device() -> str:
            return "cuda"
        except (AssertionError, RuntimeError):
            pass
+    # Intel GPU (Arc / Data Center) via the torch XPU backend. The torch.xpu
+    # namespace exists in stock wheels, but is_available() is only True on an
+    # XPU-enabled build (download.pytorch.org/whl/xpu), so this is inert on the
+    # default CPU/CUDA install. Checked before the nvidia-smi path so an Intel
+    # box never triggers the CUDA reinstaller.
+    if hasattr(torch, "xpu") and torch.xpu.is_available():  # type: ignore
+        try:
+            t = torch.tensor([1.0], device="xpu")
+            _ = t + t
+            del t
+            return "xpu"
+        except (AssertionError, RuntimeError):
+            pass
    if _has_nvidia_gpu() and not os.environ.get(_CUDA_FIX_ENV_KEY):
        _reinstall_torch_cuda_and_restart()
    if hasattr(torch.backends, "mps") and torch.backends.mps.is_available():
@@ -229,6 +242,20 @@ def get_device() -> str:
    return "cpu"


+def _make_seed_generator(device: str, seed: int) -> Any:
+    """Build a seeded ``torch.Generator``, falling back to a CPU generator.
+
+    Some backends have no device-side RNG (notably certain torch-xpu builds),
+    so ``torch.Generator(device="xpu")`` can raise. A CPU generator is
+    backend-agnostic and still seeds the pipeline reproducibly, so fall back to
+    it rather than failing the run when ``--seed`` is used on such a device.
+    """
+    try:
+        return torch.Generator(device=device).manual_seed(seed)  # type: ignore
+    except (RuntimeError, TypeError):
+        return torch.Generator().manual_seed(seed)  # type: ignore
+
+
 # Keep legacy name available for backwards compatibility
 _detect_model_profile_from_id = detect_model_profile

@@ -245,7 +272,7 @@ class WatermarkRemover:

    Attributes:
        model_id: HuggingFace model ID for the diffusion model.
-        device: Device to run inference on (cuda, mps, or cpu).
+        device: Device to run inference on (cuda, xpu, mps, or cpu).
    """

    DEFAULT_MODEL_ID = DEFAULT_MODEL_ID
@@ -270,8 +297,8 @@ class WatermarkRemover:
        self.device = (device or get_device()).lower()
        if self.device == "auto":
            self.device = get_device()
-        if self.device not in {"cpu", "mps", "cuda"}:
-            raise ValueError(f"Unsupported device '{device}'. Use one of: auto, cpu, mps, cuda.")
+        if self.device not in {"cpu", "mps", "cuda", "xpu"}:
+            raise ValueError(f"Unsupported device '{device}'. Use one of: auto, cpu, mps, cuda, xpu.")
        if torch_dtype is None:
            if self.device == "cpu" or self.device == "mps":
                self.torch_dtype = torch.float32  # type: ignore
@@ -435,7 +462,7 @@ class WatermarkRemover:
        generator = None
        if seed is not None and _HAS_TORCH:
            self._set_progress(f"Setting reproducible seed: {seed}")
-            generator = torch.Generator(device=self.device).manual_seed(seed)  # type: ignore
+            generator = _make_seed_generator(self.device, seed)

        effective_steps = max(1, int(num_inference_steps * strength))
        self._set_progress(
@@ -564,7 +591,7 @@ class WatermarkRemover:
            from diffusers import DiffusionPipeline

            self._set_progress("Loading Differential-Diffusion pipeline (protect-text)...")
-            use_fp16 = self.device in {"mps", "cuda"}
+            use_fp16 = self.device in {"mps", "cuda", "xpu"}
            load_kwargs: dict[str, Any] = {
                "custom_pipeline": _DIFF_PIPELINE_NAME,
                "custom_revision": _DIFF_PIPELINE_REVISION,
@@ -42,8 +42,18 @@ _MODEL_URL = (
 )
 _MODEL_FILENAME = "text_detection_cn_ppocrv3_2023may.onnx"

-# DB detector input: long side scaled to this, rounded to a multiple of 32.
-_DET_INPUT_LONG_SIDE = 736
+# DB detector input: the image is detected at its NATIVE long side, capped at
+# this value (rounded to a multiple of 32), never upscaled. A fixed small input
+# (the old 736) downscaled large images so far that small text fell below the
+# detector's resolution and was missed -- the cause of the "small text still
+# distorts" reports (issue #14). Detection is script-agnostic (DB segments text
+# *regions*, not characters), so this recall fix applies to every language; the
+# only lever that mattered was resolution. 1536 recovers full recall down to
+# ~12 px text on a 2048 canvas at ~100 ms on CPU (a fixed 736 missed it); going
+# higher buys no measured recall at 2x+ the cost. Benchmarked in
+# scripts/text_detection_benchmark.py. Very large canvases with tiny text may
+# still need tiling -- a documented limit, not yet built.
+_DET_MAX_LONG_SIDE = 1536
 # ImageNet mean (x255) and 1/255 scale -- the normalization PP-OCRv3 expects.
 _DET_MEAN = (0.485 * 255, 0.456 * 255, 0.406 * 255)
 _DET_SCALE = 1 / 255.0
@@ -87,6 +97,21 @@ def _model_path() -> Path:
    return target


+def _detection_input_size(height: int, width: int) -> tuple[int, int]:
+    """DB-detector input ``(in_w, in_h)`` for an image of the given size.
+
+    Detect at the native long side, capped at ``_DET_MAX_LONG_SIDE`` and never
+    upscaled, each side rounded down to a multiple of 32 (the DB head requires
+    /32 dims), floored at 32. Pure function so the resolution contract (the
+    issue #14 small-text recall fix) is unit-testable without the model.
+    """
+    long_side = max(height, width)
+    scale = min(_DET_MAX_LONG_SIDE, long_side) / long_side
+    in_w = max((round(width * scale) // 32) * 32, 32)
+    in_h = max((round(height * scale) // 32) * 32, 32)
+    return in_w, in_h
+
+
 def build_change_map(
    boxes: list[NDArray[Any]],
    height: int,
@@ -154,9 +179,7 @@ class TextProtector:
            One array of four (x, y) vertices per detected text region.
        """
        height, width = bgr_image.shape[:2]
-        scale = _DET_INPUT_LONG_SIDE / max(height, width)
-        in_w = max((round(width * scale) // 32) * 32, 32)
-        in_h = max((round(height * scale) // 32) * 32, 32)
+        in_w, in_h = _detection_input_size(height, width)
        self._detector.setInputParams(
            scale=_DET_SCALE,
            size=(in_w, in_h),
@@ -51,12 +51,31 @@ def _decoder() -> Any:
    return _tm


+# JPEG quality for the false-positive durability gate (see detect_trustmark).
+# Deliberately mild: a genuine TrustMark survives far harsher, while every
+# observed false positive collapsed even at this quality.
+_REENCODE_QUALITY = 95
+
+
 def detect_trustmark(image_path: Path) -> str | None:
-    """Return a TrustMark scheme note if a TrustMark watermark is decoded, else None.
+    """Return a TrustMark scheme note if a *durable* TrustMark watermark is
+    decoded, else None.

    Returns e.g. ``"Adobe TrustMark (variant P, schema 0)"`` when the decoder
-    reports the watermark present, or None if it is absent, the optional
-    ``trustmark`` package is not installed, or the image cannot be read/decoded.
+    reports the watermark present AND it survives a mild JPEG re-encode, or None
+    if it is absent, the optional ``trustmark`` package is not installed, or the
+    image cannot be read/decoded.
+
+    **False-positive gate.** TrustMark's ``wm_present`` flag is a BCH
+    error-correction validity check, which spuriously validates on a small
+    fraction of un-watermarked images -- content-correlated, so AI-generated
+    textures trip it more often than camera photos (verified 2026-05-29 on real
+    files: the false "detections" were on Gemini / OpenAI / Doubao output that
+    cannot carry Adobe's watermark, and decoded a random-bytes secret). A genuine
+    TrustMark is a *durable* soft binding engineered to survive re-encoding (that
+    is its entire purpose once C2PA is stripped), so we re-decode after a mild
+    JPEG round-trip and require the same schema both times. Every observed false
+    positive collapsed under this gate.
    """
    if not is_available():
        return None
@@ -65,8 +84,30 @@ def detect_trustmark(image_path: Path) -> str | None:

        with Image.open(image_path) as img:
            cover = img.convert("RGB")
-        _wm_secret, wm_present, wm_schema = _decoder().decode(cover)
+        decoder = _decoder()
+        _wm_secret, wm_present, wm_schema = decoder.decode(cover)
+        if not wm_present:
+            return None
+        if not _survives_reencode(decoder, cover, wm_schema):
+            log.debug("TrustMark decode for %s did not survive re-encode; treating as false positive", image_path)
+            return None
    except Exception as exc:  # model download / decode failure / unreadable image
        log.debug("TrustMark decode failed for %s: %s", image_path, exc)
        return None
-    return f"Adobe TrustMark (variant {_MODEL_TYPE}, schema {wm_schema})" if wm_present else None
+    return f"Adobe TrustMark (variant {_MODEL_TYPE}, schema {wm_schema})"
+
+
+def _survives_reencode(decoder: Any, cover: Any, schema: int) -> bool:
+    """True if the watermark re-decodes with the same schema after a mild JPEG
+    round-trip -- the durability a genuine TrustMark guarantees, which a BCH
+    false positive (content noise) does not."""
+    import io
+
+    from PIL import Image
+
+    buffer = io.BytesIO()
+    cover.save(buffer, "JPEG", quality=_REENCODE_QUALITY)
+    buffer.seek(0)
+    with Image.open(buffer) as reencoded:
+        _secret, present, reencoded_schema = decoder.decode(reencoded.convert("RGB"))
+    return bool(present) and reencoded_schema == schema
@@ -0,0 +1,204 @@
+"""Registry of known visible watermarks.
+
+A single catalog that ties each known visible mark to (a) where it usually sits,
+(b) how to recognize it there, and (c) how to remove it. One pass over the
+registry detects every known mark in its usual place and removes the ones
+present.
+
+**Reverse-alpha only.** A known mark is a fixed semi-transparent overlay, so it
+is removed by inverting the alpha blend against a captured alpha map
+(``original = (wm - a*logo)/(1-a)``) -- exact recovery of the true pixels, not an
+inpaint guess. Detection is consistent with that: each mark is recognized by
+matching its known shape/template (the thing we invert), not by heuristics. A
+mark is therefore listed here only once a real alpha map has been captured for
+it; everything else (arbitrary logos/objects) is the user-directed
+``erase --region`` tool, not this catalog.
+
+Entries:
+  - ``gemini`` -- Google Gemini / Nano Banana sparkle, bottom-right.
+  - ``doubao`` -- ByteDance Doubao "豆包AI生成" text strip, bottom-right.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Any, Literal
+
+if TYPE_CHECKING:
+    from collections.abc import Callable
+
+    from numpy.typing import NDArray
+
+# cv2 method for the Gemini reverse-alpha edge-residual cleanup (not a standalone
+# remover): "ns" / "telea".
+InpaintMethod = Literal["telea", "ns"]
+Region = tuple[int, int, int, int]
+
+
+@dataclass(frozen=True)
+class MarkDetection:
+    """Uniform detection result for a known mark (across heterogeneous engines)."""
+
+    key: str
+    label: str
+    location: str
+    detected: bool
+    confidence: float
+    region: Region
+
+
+@dataclass(frozen=True)
+class KnownMark:
+    """A known visible watermark: where it lives, how to find and remove it."""
+
+    key: str
+    label: str
+    location: str  # usual place, human-readable ("bottom-right")
+    in_auto: bool  # participate in `--mark auto` scanning
+    recovery: str  # removal strategy (all reverse-alpha today)
+    _detect: Callable[[NDArray[Any]], MarkDetection]
+    _remove: Callable[..., tuple[NDArray[Any], Region | None]]
+
+    def detect(self, image: NDArray[Any]) -> MarkDetection:
+        return self._detect(image)
+
+    def remove(
+        self,
+        image: NDArray[Any],
+        *,
+        inpaint_method: InpaintMethod = "ns",
+        inpaint: bool = True,
+        inpaint_strength: float = 0.85,
+        force: bool = False,
+    ) -> tuple[NDArray[Any], Region | None]:
+        """Remove this mark by reverse-alpha; returns ``(result, region)`` where
+        ``region`` is the removed mark's bbox (for residual-inpaint positioning),
+        or None if nothing was removed. NB: the CLI does NOT use ``region`` to
+        clear alpha on save -- that zeroing caused the issue-#30 white box.
+
+        ``inpaint`` / ``inpaint_strength`` / ``inpaint_method`` tune the Gemini
+        reverse-alpha edge-residual cleanup only. ``force`` removes at the mark's
+        usual location even without a positive detection (the ``--no-detect`` path).
+        """
+        return self._remove(image, inpaint_method, inpaint, inpaint_strength, force)
+
+
+# Gemini-sparkle confidence above which the registry treats it as a confident
+# detection for arbitration. Matches identify's corpus-validated sparkle
+# threshold (0.5): the gemini engine's own detect flag uses a looser internal
+# threshold and weakly fires (~0.36) on unrelated bottom-right text (e.g. the
+# Doubao mark), which would otherwise let it hijack `--mark auto`. 0.5 gives 0
+# false positives on the corpus.
+_GEMINI_AUTO_MIN_CONF = 0.5
+
+# ── Engine adapters (lazy singletons; engines are cv2-only, no model load) ──
+
+_engines: dict[str, Any] = {}
+
+
+def _engine(key: str) -> Any:
+    if key not in _engines:
+        if key == "gemini":
+            from remove_ai_watermarks.gemini_engine import GeminiEngine
+
+            _engines[key] = GeminiEngine()
+        elif key == "doubao":
+            from remove_ai_watermarks.doubao_engine import DoubaoEngine
+
+            _engines[key] = DoubaoEngine()
+        else:  # pragma: no cover - guarded by the registry keys
+            raise KeyError(key)
+    return _engines[key]
+
+
+def _gemini_detect(image: NDArray[Any]) -> MarkDetection:
+    d = _engine("gemini").detect_watermark(image)
+    detected = bool(d.detected) and d.confidence >= _GEMINI_AUTO_MIN_CONF
+    return MarkDetection("gemini", "Google Gemini sparkle", "bottom-right", detected, d.confidence, d.region)
+
+
+def _gemini_remove(
+    image: NDArray[Any], inpaint_method: InpaintMethod, inpaint: bool, strength: float, force: bool
+) -> tuple[NDArray[Any], Region | None]:
+    engine = _engine("gemini")
+    det = engine.detect_watermark(image)
+    if not det.detected:
+        if not force:
+            return image.copy(), None
+        # Forced (--no-detect): remove at the default sparkle slot for the size.
+        from remove_ai_watermarks.gemini_engine import get_watermark_config
+
+        h, w = image.shape[:2]
+        cfg = get_watermark_config(w, h)
+        px, py = cfg.get_position(w, h)
+        region = (px, py, cfg.logo_size, cfg.logo_size)
+        result = engine.remove_watermark_custom(image, region)
+        if inpaint:
+            result = engine.inpaint_residual(result, region, strength=strength, method=inpaint_method)
+        return result, region
+    result = engine.remove_watermark(image)
+    # Reverse-alpha leaves a faint residual at the sparkle edge; the engine's
+    # own residual inpaint cleans that seam (part of its reverse-alpha pipeline).
+    if inpaint:
+        result = engine.inpaint_residual(result, det.region, strength=strength, method=inpaint_method)
+    return result, det.region
+
+
+def _doubao_detect(image: NDArray[Any]) -> MarkDetection:
+    d = _engine("doubao").detect(image)
+    return MarkDetection("doubao", "Doubao 豆包AI生成 text", "bottom-right", d.detected, d.confidence, d.region)
+
+
+def _doubao_remove(
+    image: NDArray[Any], _inpaint_method: InpaintMethod, _inpaint: bool, _strength: float, force: bool
+) -> tuple[NDArray[Any], Region | None]:
+    # Reverse-alpha only: apply when the mark is present AND the resolution is in
+    # the alpha map's calibrated band. Outside it we do NOT inpaint (no
+    # hallucination) -- removal is skipped until a capture for that resolution.
+    engine = _engine("doubao")
+    det = engine.detect(image)
+    if (det.detected or force) and engine.reverse_alpha_available(image):
+        return engine.remove_watermark_reverse_alpha(image), (det.region if det.detected else None)
+    return image.copy(), None
+
+
+_REGISTRY: tuple[KnownMark, ...] = (
+    KnownMark("gemini", "Google Gemini sparkle", "bottom-right", True, "reverse-alpha", _gemini_detect, _gemini_remove),
+    KnownMark(
+        "doubao", "Doubao 豆包AI生成 text", "bottom-right", True, "reverse-alpha", _doubao_detect, _doubao_remove
+    ),
+)
+
+
+def known_marks() -> tuple[KnownMark, ...]:
+    """All registered known visible watermarks."""
+    return _REGISTRY
+
+
+def mark_keys() -> list[str]:
+    """Keys of all registered marks (for CLI choices)."""
+    return [m.key for m in _REGISTRY]
+
+
+def get_mark(key: str) -> KnownMark:
+    """Look up a known mark by key (raises KeyError if unknown)."""
+    for m in _REGISTRY:
+        if m.key == key:
+            return m
+    raise KeyError(key)
+
+
+def detect_marks(image: NDArray[Any], *, include_explicit: bool = True) -> list[MarkDetection]:
+    """Detect every known mark in its usual place.
+
+    Returns one MarkDetection per scanned mark (``detected`` flags which fired).
+    ``include_explicit=False`` scans only the ``in_auto`` marks -- the set used
+    by ``--mark auto``.
+    """
+    return [m.detect(image) for m in _REGISTRY if include_explicit or m.in_auto]
+
+
+def best_auto_mark(image: NDArray[Any]) -> MarkDetection | None:
+    """The highest-confidence detected ``in_auto`` mark, or None if none fired."""
+    fired = [d for d in detect_marks(image, include_explicit=False) if d.detected]
+    return max(fired, key=lambda d: d.confidence) if fired else None
@@ -198,15 +198,17 @@ class TestVisibleCommand:
        # which doesn't overlap the centre square at 200x200).
        assert out[100, 100, 3] == 255

-    def test_visible_clears_alpha_in_watermark_region(self, runner, tmp_path):
-        """When inpainting an RGBA image, the watermark region must be cleared
-        in the alpha channel so the sparkle area becomes transparent, not opaque-black.
+    def test_visible_keeps_alpha_opaque_in_watermark_region(self, runner, tmp_path):
+        """Regression for issue #30 (white box): on an opaque RGBA image, the
+        watermark region must stay OPAQUE. Reverse-alpha recovers real pixels
+        there, so zeroing alpha would punch a transparent hole that renders as a
+        solid white box on any non-transparent viewer.
        """
        rgba = np.full((200, 200, 4), 255, dtype=np.uint8)  # fully opaque white
        src = tmp_path / "rgba_full.png"
        cv2.imwrite(str(src), rgba)

-        output = tmp_path / "rgba_cleared.png"
+        output = tmp_path / "rgba_kept.png"
        result = runner.invoke(
            main,
            ["visible", str(src), "-o", str(output), "--no-detect"],
@@ -215,13 +217,15 @@ class TestVisibleCommand:
        assert result.exit_code == 0, result.output
        out = cv2.imread(str(output), cv2.IMREAD_UNCHANGED)
        assert out.shape[2] == 4
-        # Default sparkle position is in the bottom-right; alpha there must be 0.
+        # Default sparkle position is in the bottom-right; alpha there must stay 255.
        from remove_ai_watermarks.gemini_engine import get_watermark_config

        cfg = get_watermark_config(200, 200)
        px, py = cfg.get_position(200, 200)
        size = cfg.logo_size
-        assert out[py + size // 2, px + size // 2, 3] == 0, "alpha in the watermark region was not cleared"
+        assert out[py + size // 2, px + size // 2, 3] == 255, "watermark region alpha was zeroed (white-box regression)"
+        # No pixel anywhere should have been forced transparent.
+        assert int((out[:, :, 3] == 0).sum()) == 0, "spurious transparent pixels introduced"

    def test_visible_rgb_input_stays_rgb(self, runner, sample_png, tmp_path):
        """Regression: a plain RGB PNG must NOT gain a spurious alpha channel."""
@@ -249,6 +253,7 @@ class TestInvisibleCommand:
        mock_cls, mock_engine = _mock_invisible_engine()
        output = tmp_path / "clean.png"
        with (
+            patch("remove_ai_watermarks.invisible_engine.is_available", return_value=True),
            patch("remove_ai_watermarks.cli.InvisibleEngine", mock_cls, create=True),
            patch("remove_ai_watermarks.invisible_engine.InvisibleEngine", mock_cls),
        ):
@@ -263,6 +268,7 @@ class TestInvisibleCommand:
    def test_invisible_default_output(self, runner, sample_png):
        mock_cls, _mock_engine = _mock_invisible_engine()
        with (
+            patch("remove_ai_watermarks.invisible_engine.is_available", return_value=True),
            patch("remove_ai_watermarks.cli.InvisibleEngine", mock_cls, create=True),
            patch("remove_ai_watermarks.invisible_engine.InvisibleEngine", mock_cls),
        ):
@@ -1,4 +1,4 @@
-"""Tests for the Doubao visible-watermark engine."""
+"""Tests for the Doubao visible-watermark engine (reverse-alpha only)."""

 from __future__ import annotations

@@ -8,91 +8,156 @@ import cv2
 import numpy as np
 import pytest

-from remove_ai_watermarks.doubao_engine import DoubaoEngine, load_image_bgr
+from remove_ai_watermarks.doubao_engine import (
+    _ALPHA_HEIGHT_FRAC,
+    _ALPHA_LOGO_BGR,
+    _ALPHA_MARGIN_BOTTOM_FRAC,
+    _ALPHA_MARGIN_RIGHT_FRAC,
+    _ALPHA_NATIVE_WIDTH,
+    _ALPHA_WIDTH_FRAC,
+    DETECT_NCC_THRESHOLD,
+    DoubaoEngine,
+    _alpha_template,
+    _glyph_silhouette,
+    _template_match_score,
+    load_image_bgr,
+)

 SAMPLE = Path(__file__).resolve().parents[1] / "data" / "samples" / "doubao-1.png"


-# ── Locate ──────────────────────────────────────────────────────────
-
-
 class TestLocate:
    def test_box_anchored_bottom_right(self):
        eng = DoubaoEngine()
        img = np.zeros((2048, 2048, 3), np.uint8)
        loc = eng.locate(img)
-        # right and bottom edges sit close to the image corner (within margins)
        assert 2048 - (loc.x + loc.w) < int(2048 * 0.03)
        assert 2048 - (loc.y + loc.h) < int(2048 * 0.03)
-        assert loc.is_fallback  # geometry anchor, no bundled template yet

    def test_box_scales_with_width(self):
        eng = DoubaoEngine()
        small = eng.locate(np.zeros((1024, 1024, 3), np.uint8))
        large = eng.locate(np.zeros((2048, 2048, 3), np.uint8))
-        # width-relative geometry: 2x wider image -> ~2x wider box
        assert large.w == pytest.approx(small.w * 2, rel=0.1)


-# ── Detect + remove on the real sample ──────────────────────────────
+# ── Detection: alpha-template NCC ───────────────────────────────────
+
+
+class TestDetect:
+    def test_clean_gradient_not_detected(self):
+        eng = DoubaoEngine()
+        ramp = np.tile(np.linspace(0, 255, 1024, dtype=np.uint8), (1024, 1))
+        img = cv2.cvtColor(ramp, cv2.COLOR_GRAY2BGR)
+        assert not eng.detect(img).detected
+
+    def test_solid_blob_corner_not_detected(self):
+        """A bright blob is not the glyph shape -> low correlation, not detected."""
+        eng = DoubaoEngine()
+        img = np.zeros((1024, 1024, 3), np.uint8)
+        x, y, bw, bh = eng.locate(img).bbox
+        img[y + bh // 4 : y + bh * 3 // 4, x : x + bw // 2] = 200
+        assert not eng.detect(img).detected
+
+    def test_silhouette_loads(self):
+        sil = _glyph_silhouette()
+        assert sil is not None
+        assert set(np.unique(sil)).issubset({0, 255})
+
+    def test_match_score_shape_sensitive(self):
+        """The glyph silhouette correlates with itself, not with a filled block."""
+        sil = _glyph_silhouette()
+        h, w = sil.shape
+        # box that contains the silhouette -> high score
+        box = np.zeros((h + 8, int(w / _ALPHA_WIDTH_FRAC * 0.2) + w), np.uint8)
+        box[4 : 4 + h, 4 : 4 + w] = sil
+        assert _template_match_score(box, _ALPHA_NATIVE_WIDTH) >= DETECT_NCC_THRESHOLD
+        # a uniformly filled box has no glyph structure -> low score
+        solid = np.full_like(box, 255)
+        assert _template_match_score(solid, _ALPHA_NATIVE_WIDTH) < DETECT_NCC_THRESHOLD


@pytest.mark.skipif(not SAMPLE.exists(), reason="sample image not present")
 class TestRealSample:
    def test_detects_watermark(self):
-        eng = DoubaoEngine()
-        det = eng.detect(load_image_bgr(SAMPLE))
+        det = DoubaoEngine().detect(load_image_bgr(SAMPLE))
        assert det.detected
-        assert det.confidence > 0.0
-        assert det.coverage > 0.04
+        assert det.confidence >= DETECT_NCC_THRESHOLD

-    def test_remove_reduces_glyph_coverage(self):
+    def test_reverse_alpha_removes_mark(self):
        eng = DoubaoEngine()
        img = load_image_bgr(SAMPLE)
-        before = eng.detect(img).coverage
-        out = eng.remove_watermark(img)
-        after = eng.detect(out).coverage
-        # the inpaint should clear most glyph pixels from the corner box
-        assert after < before * 0.5
+        assert eng.reverse_alpha_available(img)  # sample is at the captured width
+        out = eng.remove_watermark_reverse_alpha(img)
+        assert not eng.detect(out).detected  # mark gone after recovery

-    def test_pixels_outside_box_untouched(self):
+    def test_far_region_untouched(self):
        eng = DoubaoEngine()
        img = load_image_bgr(SAMPLE)
-        out = eng.remove_watermark(img)
-        # top-left quadrant is far from the bottom-right mark: must be identical
+        out = eng.remove_watermark_reverse_alpha(img)
        h, w = img.shape[:2]
        assert np.array_equal(img[: h // 2, : w // 2], out[: h // 2, : w // 2])


-# ── Negative + safety guard ─────────────────────────────────────────
+# ── Reverse-alpha (exact recovery) ──────────────────────────────────


-class TestNegativeAndGuard:
-    def test_clean_image_not_detected(self):
+class TestReverseAlpha:
+    def test_alpha_asset_loads(self):
+        at = _alpha_template()
+        assert at is not None
+        assert at.dtype.kind == "f"
+        assert float(at.min()) >= 0.0
+        assert float(at.max()) <= 1.0
+
+    def test_available_whenever_asset_present(self):
+        # NCC alignment generalizes to any resolution, so availability is just
+        # "asset loadable" (any non-empty image); the caller gates on detect.
        eng = DoubaoEngine()
-        # smooth gradient, no watermark
-        ramp = np.tile(np.linspace(0, 255, 1024, dtype=np.uint8), (1024, 1))
-        img = cv2.cvtColor(ramp, cv2.COLOR_GRAY2BGR)
-        det = eng.detect(img)
-        assert not det.detected
+        assert eng.reverse_alpha_available(np.zeros((1024, 1024, 3), np.uint8))
+        assert eng.reverse_alpha_available(np.zeros((1773, 1535, 3), np.uint8))
+        assert not eng.reverse_alpha_available(np.zeros((0, 0, 3), np.uint8))

-    def test_clean_image_returned_unchanged(self):
-        eng = DoubaoEngine()
-        ramp = np.tile(np.linspace(0, 255, 1024, dtype=np.uint8), (1024, 1))
-        img = cv2.cvtColor(ramp, cv2.COLOR_GRAY2BGR)
-        out = eng.remove_watermark(img)
-        assert np.array_equal(img, out)
+    @staticmethod
+    def _compose(w: int, h: int, bg: float = 100.0):
+        """Composite the real alpha (scaled to width ``w``) onto a flat bg.
+        Returns ``(watermarked_uint8, mark_bool_mask)``."""
+        img = np.full((h, w, 3), bg, np.float32)
+        at = _alpha_template()
+        gw, gh = int(_ALPHA_WIDTH_FRAC * w), int(_ALPHA_HEIGHT_FRAC * w)
+        ax = w - int(_ALPHA_MARGIN_RIGHT_FRAC * w) - gw
+        ay = h - int(_ALPHA_MARGIN_BOTTOM_FRAC * w) - gh
+        amap = np.zeros((h, w), np.float32)
+        amap[ay : ay + gh, ax : ax + gw] = cv2.resize(at, (gw, gh))
+        a3 = amap[:, :, None]
+        wm = (a3 * np.array(_ALPHA_LOGO_BGR, np.float32) + (1 - a3) * img).clip(0, 255).astype(np.uint8)
+        return wm, amap > 0.2

-    def test_document_background_guard(self):
-        """A dense high-frequency corner (document-like) trips the coverage
-        guard, so the image is left untouched rather than smeared."""
+    def test_native_returns_exact_reverse_alpha_no_inpaint(self):
+        """At native width the recovery is exact, so it must be returned untouched
+        -- inpainting over exactly-recovered interior pixels degrades quality
+        (regression: native textured error 1.6 reverse-alpha-only vs 2.6 with the
+        old full-footprint inpaint). The output must equal pure reverse-alpha."""
        eng = DoubaoEngine()
-        rng = np.random.default_rng(0)
-        img = np.full((1024, 1024, 3), 255, np.uint8)
-        # fill the bottom-right box area with random grayish text-like noise
-        loc = eng.locate(img)
-        x, y, bw, bh = loc.bbox
-        noise = rng.integers(150, 246, size=(bh, bw), dtype=np.uint8)
-        img[y : y + bh, x : x + bw] = noise[:, :, None]
-        out = eng.remove_watermark(img)
-        assert np.array_equal(img, out)
+        wm, _mark = self._compose(_ALPHA_NATIVE_WIDTH, _ALPHA_NATIVE_WIDTH)
+        out = eng.remove_watermark_reverse_alpha(wm)
+        amap = eng._fixed_alpha_map(wm)
+        assert amap is not None
+        expected = eng._apply_reverse_alpha(wm, amap[0])
+        assert np.array_equal(out, expected)  # no inpaint touched the recovery
+
+    @pytest.mark.parametrize(
+        ("w", "h", "max_err"),
+        [
+            (_ALPHA_NATIVE_WIDTH, _ALPHA_NATIVE_WIDTH, 5.0),  # native 1:1 -> fixed geometry, ~exact
+            (1773, 2364, 8.0),  # 3:4 portrait -> NCC alignment generalizes the single capture
+        ],
+    )
+    def test_recovers_flat_background(self, w, h, max_err):
+        """Recovers the flat background at native (fixed geometry, exact) AND a
+        non-native resolution (NCC alignment generalizes the single capture)."""
+        eng = DoubaoEngine()
+        wm, mark = self._compose(w, h)
+        assert float(np.abs(wm.astype(np.float32)[mark] - 100.0).mean()) > 15  # mark visible
+        out = eng.remove_watermark_reverse_alpha(wm).astype(np.float32)
+        assert float(np.abs(out[mark] - 100.0).mean()) < max_err
@@ -113,6 +113,18 @@ class TestIdentifyNonPng:
        r = identify(path, check_visible=False)
        assert any("SynthID" in w for w in r.watermarks)

+    def test_black_forest_labs_flux_attributed(self, tmp_path: Path):
+        path = self._c2pa_jpeg(tmp_path, b"Black Forest Labs API ... trainedAlgorithmicMedia")
+        r = identify(path, check_visible=False, check_invisible=False)
+        assert r.is_ai_generated is True
+        assert r.platform == "Black Forest Labs (FLUX)"
+
+    def test_bytedance_volcengine_attributed(self, tmp_path: Path):
+        path = self._c2pa_jpeg(tmp_path, b"certificate_center@volcengine.com ... trainedAlgorithmicMedia")
+        r = identify(path, check_visible=False, check_invisible=False)
+        assert r.is_ai_generated is True
+        assert "ByteDance" in (r.platform or "")
+
    def test_stability_ai_issuer_attributed_no_synthid(self, tmp_path: Path):
        path = self._c2pa_jpeg(tmp_path, b"Stability AI ... trainedAlgorithmicMedia")
        r = identify(path, check_visible=False)
@@ -132,6 +144,50 @@ class TestIdentifyNonPng:
        assert not any("SynthID" in w for w in r.watermarks)


+class TestIdentifySamsungGalaxy:
+    """Samsung Galaxy / ASUS Gallery C2PA signers (verified on real signed files
+    2026-05-29; synthetic byte blobs here since the originals are private).
+
+    Galaxy AI edits stamp BOTH the device cert AND an AI source-type / genAIType,
+    so the signer attribution must NOT trip the camera-vs-AI integrity clash.
+    """
+
+    def _jpeg(self, tmp_path: Path, name: str, blob: bytes) -> Path:
+        path = tmp_path / name
+        path.write_bytes(b"\xff\xd8\xff\xe1jumbc2pa" + blob + b"\xff\xd9")
+        return path
+
+    def test_galaxy_trained_source_is_high_ai(self, tmp_path: Path):
+        path = self._jpeg(tmp_path, "s25.jpg", b"Samsung Galaxy Galaxy S25 c2pa-rs trainedAlgorithmicMedia")
+        r = identify(path, check_visible=False, check_invisible=False)
+        assert r.is_ai_generated is True
+        assert r.confidence == "high"
+        assert r.platform == "Samsung Galaxy (C2PA)"
+        assert r.integrity_clashes == []  # device cert + AI source-type is legitimate, not a clash
+
+    def test_galaxy_genai_only_is_medium_ai(self, tmp_path: Path):
+        # The Galaxy S24 case: no trainedAlgorithmicMedia, genAIType is the only
+        # AI marker -- previously missed, now a medium-confidence verdict.
+        path = self._jpeg(
+            tmp_path, "s24.jpg", b'Samsung Galaxy Galaxy S24 c2pa-rs PhotoEditor_Re_Edit_Data{"genAIType":1}'
+        )
+        r = identify(path, check_visible=False, check_invisible=False)
+        assert r.is_ai_generated is True
+        assert r.confidence == "medium"
+        assert r.platform == "Samsung Galaxy (C2PA)"
+        assert any(s.name == "samsung_genai" for s in r.signals)
+        assert r.integrity_clashes == []
+
+    def test_asus_gallery_signer_not_ai(self, tmp_path: Path):
+        # ASUS Gallery signs edited photos; no AI source-type or genAIType, so the
+        # platform is attributed but the verdict stays unknown.
+        path = self._jpeg(tmp_path, "asus.jpg", b"/com.asus.gallery/3.8.0.98 c2pa-rs no ai marker")
+        r = identify(path, check_visible=False, check_invisible=False)
+        assert r.is_ai_generated is None
+        assert r.platform == "ASUS Gallery (C2PA signer)"
+        assert any("C2PA" in w for w in r.watermarks)
+
+
 # ── End-to-end verdicts on real fixtures ────────────────────────────


@@ -12,9 +12,15 @@ class TestIsAvailable:
        result = is_available()
        assert isinstance(result, bool)

-    def test_available_when_torch_installed(self):
-        """torch + diffusers should be installed in dev env."""
-        assert is_available() is True
+    def test_available_reflects_dependencies(self):
+        """is_available() is True iff torch + diffusers (the gpu extra) import.
+
+        Must not assume the full stack: the core+dev CI env has no diffusers.
+        """
+        import importlib.util
+
+        expected = all(importlib.util.find_spec(m) is not None for m in ("torch", "diffusers"))
+        assert is_available() is expected


 class TestInvisibleEngineInit:
@@ -12,12 +12,15 @@ from PIL import Image
 from PIL.PngImagePlugin import PngInfo

 from remove_ai_watermarks.metadata import (
+    C2PA_UUID,
    _is_ai_key,
+    c2pa_marker_in,
    exif_generator,
    get_ai_metadata,
    has_ai_metadata,
    iptc_ai_system,
    remove_ai_metadata,
+    samsung_genai,
    synthid_source,
    xai_signature,
 )
@@ -135,6 +138,71 @@ class TestHasAiMetadata:
        assert has_ai_metadata(path)


+class TestC2paMarkerIn:
+    """The C2PA presence check requires a JUMBF wrapper or the C2PA uuid box, so
+    a bare 4-byte ``c2pa`` substring (e.g. random compressed pixel data) does not
+    false-positive -- the regression behind 4 cleaned PNGs re-flagging C2PA."""
+
+    def test_jumbf_wrapped_c2pa_detected(self):
+        assert c2pa_marker_in(b"....jumbc2pa....manifest....") is True
+
+    def test_c2pa_uuid_box_detected(self):
+        assert c2pa_marker_in(b"\x00\x00\x00\x18uuid" + C2PA_UUID + b"payload") is True
+
+    def test_bare_c2pa_substring_not_detected(self):
+        # The exact false positive: "c2pa" appears in noise but no JUMBF/uuid box.
+        assert c2pa_marker_in(b"\x9c\xc3\xa7B1\x11c2pa\x80b\x804\xc5\xf9random idat") is False
+
+    def test_jumb_without_c2pa_not_detected(self):
+        assert c2pa_marker_in(b"some jumb box but no manifest label") is False
+
+    def test_empty_not_detected(self):
+        assert c2pa_marker_in(b"") is False
+
+
+class TestSamsungGenai:
+    """Samsung Galaxy AI editing marker (genAIType in PhotoEditor_Re_Edit_Data).
+
+    Synthetic byte blobs -- real Galaxy files are user content and not shipped
+    (public repo), same discipline as the Grok/Doubao fixtures.
+    """
+
+    @staticmethod
+    def _samsung_jpeg(tmp_path: Path, name: str, payload: bytes) -> Path:
+        path = tmp_path / name
+        path.write_bytes(b"\xff\xd8\xff\xe1" + payload + b"\xff\xd9")
+        return path
+
+    def test_nonzero_genai_type_detected(self, tmp_path: Path):
+        p = self._samsung_jpeg(
+            tmp_path, "galaxy.jpg", b'PhotoEditor_Re_Edit_Data{"connectorType":"srvg","genAIType":1}'
+        )
+        assert samsung_genai(p) == 1
+
+    def test_other_nonzero_value_detected(self, tmp_path: Path):
+        p = self._samsung_jpeg(tmp_path, "galaxy5.jpg", b'PhotoEditor_Re_Edit_Data{"genAIType":5}')
+        assert samsung_genai(p) == 5
+
+    def test_zero_genai_type_is_none(self, tmp_path: Path):
+        """genAIType:0 means no generative AI was used -- not a positive signal."""
+        p = self._samsung_jpeg(tmp_path, "edit.jpg", b'PhotoEditor_Re_Edit_Data{"genAIType":0}')
+        assert samsung_genai(p) is None
+
+    def test_genai_without_editor_container_ignored(self, tmp_path: Path):
+        """An incidental genAIType token outside Samsung's editor JSON is ignored."""
+        p = self._samsung_jpeg(tmp_path, "stray.jpg", b'some other blob "genAIType":1 elsewhere')
+        assert samsung_genai(p) is None
+
+    def test_clean_image_is_none(self, tmp_clean_png):
+        assert samsung_genai(tmp_clean_png) is None
+
+    def test_surfaced_in_get_ai_metadata(self, tmp_path: Path):
+        p = self._samsung_jpeg(tmp_path, "galaxy.jpg", b'PhotoEditor_Re_Edit_Data{"genAIType":1}')
+        meta = get_ai_metadata(p)
+        assert "samsung_genai" in meta
+        assert "genAIType=1" in meta["samsung_genai"]
+
+
 class TestGetAiMetadata:
    """Tests for extracting AI metadata."""

@@ -637,6 +705,82 @@ class TestAIGCLabel:
        assert aigc_label(out) is None
        assert not has_ai_metadata(out)

+    def _aigc_exif_jpeg(self, tmp_path: Path, producer: str = "001191440300708461136T1308L") -> Path:
+        """Some China-served generators embed the raw-JSON ``{"AIGC":{...}}``
+        block in JPEG EXIF (UserComment) -- no PNG chunk, no namespaced XMP."""
+        import json
+
+        import piexif
+
+        p = tmp_path / "aigc_exif.jpg"
+        Image.new("RGB", (32, 32)).save(p)
+        payload = json.dumps({"AIGC": {"Label": "1", "ContentProducer": producer, "ProduceID": "abc123"}})
+        exif = {"Exif": {piexif.ExifIFD.UserComment: payload.encode("ascii")}}
+        piexif.insert(piexif.dump(exif), str(p))
+        return p
+
+    def test_parses_raw_json_exif_form(self, tmp_path: Path):
+        from remove_ai_watermarks.metadata import aigc_label
+
+        info = aigc_label(self._aigc_exif_jpeg(tmp_path))
+        assert info is not None
+        assert info["Label"] == "1"
+        assert info["ContentProducer"] == "001191440300708461136T1308L"
+
+    def test_has_ai_metadata_detects_raw_json_exif_form(self, tmp_path: Path):
+        assert has_ai_metadata(self._aigc_exif_jpeg(tmp_path))
+
+    def test_raw_json_without_tc260_field_ignored(self, tmp_path: Path):
+        """A bare ``{"AIGC":{...}}`` object with no TC260 field must not fire."""
+        import json
+
+        import piexif
+
+        from remove_ai_watermarks.metadata import aigc_label
+
+        p = tmp_path / "unrelated.jpg"
+        Image.new("RGB", (32, 32)).save(p)
+        payload = json.dumps({"AIGC": {"unrelated": "value"}})
+        exif = {"Exif": {piexif.ExifIFD.UserComment: payload.encode("ascii")}}
+        piexif.insert(piexif.dump(exif), str(p))
+        assert aigc_label(p) is None
+
+    def _aigc_attr_png(self, tmp_path: Path, producer: str = "picwish") -> Path:
+        """PicWish writes the TC260 label as an XMP *attribute*
+        (``TC260:AIGC="{...}"``), not the nested element form."""
+        p = tmp_path / "picwish.png"
+        Image.new("RGB", (32, 32)).save(p)
+        xmp = (
+            '<rdf:Description rdf:about="" '
+            'xmlns:TC260="http://www.tc260.org.cn/ns/AIGC/1.0/" '
+            f'TC260:AIGC="{{&quot;Label&quot;:&quot;1&quot;,&quot;ContentProducer&quot;:&quot;{producer}&quot;}}"/>'
+        )
+        with open(p, "ab") as f:
+            f.write(xmp.encode())
+        return p
+
+    def test_parses_xmp_attribute_form(self, tmp_path: Path):
+        from remove_ai_watermarks.metadata import aigc_label
+
+        info = aigc_label(self._aigc_attr_png(tmp_path))
+        assert info is not None
+        assert info["ContentProducer"] == "picwish"
+
+    def test_scan_head_collects_png_metadata_past_window(self, tmp_path: Path):
+        """A PNG metadata chunk beyond the read window is still reachable -- the
+        regression for a TC260 XMP packet appended after a large IDAT."""
+        import json
+
+        from remove_ai_watermarks.metadata import _png_late_metadata, scan_head
+
+        p = tmp_path / "late.png"
+        pnginfo = PngInfo()
+        pnginfo.add_text("AIGC", json.dumps({"Label": "1", "ContentProducer": "doubao"}))
+        Image.new("RGB", (16, 16)).save(p, pnginfo=pnginfo)
+        # window = 8 (just the signature) makes the text chunk "late".
+        assert b"ContentProducer" in _png_late_metadata(p, 8)
+        assert b"ContentProducer" in scan_head(p, 8)
+

 class TestHuggingFaceJob:
    """HuggingFace-hosted job marker (``hf-job-id`` PNG text chunk)."""
@@ -6,7 +6,7 @@ code paths work correctly on CPU, MPS (macOS), and CUDA (Linux/Windows).

 from __future__ import annotations

-from unittest.mock import patch
+from unittest.mock import MagicMock, patch

 import pytest

@@ -27,7 +27,7 @@ class TestDeviceDetection:

    def test_returns_valid_device(self):
        device = get_device()
-        assert device in ("cpu", "mps", "cuda")
+        assert device in ("cpu", "mps", "cuda", "xpu")

    def test_cpu_fallback_when_no_gpu(self):
        """On CI / machines without GPU, should fall back to cpu or mps."""
@@ -39,6 +39,49 @@ class TestDeviceDetection:
    def test_no_torch_returns_cpu(self):
        assert get_device() == "cpu"

+    def test_xpu_selected_when_available(self):
+        """An XPU-enabled torch (no CUDA) routes to the Intel GPU backend.
+
+        The whole torch module is mocked so the smoke-test ops succeed without
+        any real device; cuda must read False so the cuda branch is skipped.
+        """
+        fake_torch = MagicMock()
+        fake_torch.cuda.is_available.return_value = False
+        fake_torch.xpu.is_available.return_value = True
+        with patch("remove_ai_watermarks.noai.watermark_remover.torch", fake_torch):
+            assert get_device() == "xpu"
+        fake_torch.tensor.assert_called_with([1.0], device="xpu")
+
+    def test_init_accepts_xpu_and_selects_fp16(self):
+        """WatermarkRemover accepts device='xpu' and picks fp16 (not fp32)."""
+        if not is_watermark_removal_available():
+            pytest.skip("torch/diffusers not installed")
+        import torch
+
+        from remove_ai_watermarks.noai.watermark_remover import WatermarkRemover
+
+        remover = WatermarkRemover(device="xpu")
+        assert remover.device == "xpu"
+        assert remover.torch_dtype == torch.float16
+
+    def test_seed_generator_falls_back_to_cpu_when_device_rng_unsupported(self):
+        """A device with no RNG backend (e.g. some torch-xpu builds) falls back
+        to a CPU generator instead of raising when --seed is used."""
+        from remove_ai_watermarks.noai import watermark_remover as wr
+
+        def fake_generator(device="cpu"):
+            if device == "xpu":
+                raise RuntimeError("Device type xpu is not supported for torch.Generator()")
+            gen = MagicMock()
+            gen.manual_seed.return_value = f"gen:{device}"
+            return gen
+
+        fake_torch = MagicMock()
+        fake_torch.Generator.side_effect = fake_generator
+        with patch.object(wr, "torch", fake_torch):
+            assert wr._make_seed_generator("xpu", 123) == "gen:cpu"
+            assert wr._make_seed_generator("cuda", 123) == "gen:cuda"
+

 class TestMpsErrorDetection:
    """Tests for MPS error detection helper."""
@@ -151,13 +194,21 @@ class TestAvailability:
    """Tests for dependency availability checks."""

    def test_watermark_removal_available(self):
-        # In dev env with torch+diffusers installed
-        assert is_watermark_removal_available() is True
+        # Reflects the actual environment: True iff torch + diffusers (the gpu
+        # extra) are importable. The core+dev CI env has no diffusers, so this
+        # must not assume the full stack is present.
+        import importlib.util
+
+        expected = all(importlib.util.find_spec(m) is not None for m in ("torch", "diffusers"))
+        assert is_watermark_removal_available() is expected

    def test_invisible_is_available(self):
+        import importlib.util
+
        from remove_ai_watermarks.invisible_engine import is_available

-        assert is_available() is True
+        expected = all(importlib.util.find_spec(m) is not None for m in ("torch", "diffusers"))
+        assert is_available() is expected


 # ── Platform-specific path handling ─────────────────────────────────
@@ -11,7 +11,50 @@ from __future__ import annotations

 import numpy as np

-from remove_ai_watermarks.text_protector import build_change_map
+from remove_ai_watermarks.text_protector import _DET_MAX_LONG_SIDE, _detection_input_size, build_change_map
+
+
+class TestDetectionInputSize:
+    """Resolution contract for the DB detector input (issue #14 recall fix).
+
+    A fixed small input (the old 736) downscaled large canvases so far that small
+    text fell below the detector's resolution and was missed. Detection now runs
+    at the native long side, capped and never upscaled.
+    """
+
+    def test_large_canvas_not_downscaled_to_old_736(self):
+        # The #14 regression: a 2048 canvas must detect well above the old 736
+        # so ~12-16 px text survives. Capped at the max long side.
+        in_w, in_h = _detection_input_size(2048, 2048)
+        assert in_w == _DET_MAX_LONG_SIDE
+        assert in_h == _DET_MAX_LONG_SIDE
+        assert in_w > 736  # the old fixed input that missed small text
+
+    def test_native_resolution_not_upscaled(self):
+        # A 1024 canvas detects at native 1024 (not upscaled to the cap, not
+        # downscaled to the old 736).
+        assert _detection_input_size(1024, 1024) == (1024, 1024)
+
+    def test_small_image_is_native(self):
+        assert _detection_input_size(512, 512) == (512, 512)
+
+    def test_dims_are_multiples_of_32(self):
+        for h, w in [(2048, 1024), (1234, 567), (4096, 4096), (1000, 1000)]:
+            in_w, in_h = _detection_input_size(h, w)
+            assert in_w % 32 == 0
+            assert in_h % 32 == 0
+
+    def test_aspect_ratio_preserved_when_capped(self):
+        # Portrait 2048x1024: long side capped to the max, short side scaled by
+        # the same factor (so the 2:1 aspect is roughly kept).
+        in_w, in_h = _detection_input_size(2048, 1024)
+        assert in_h == _DET_MAX_LONG_SIDE
+        assert abs((in_w / in_h) - 0.5) < 0.05
+
+    def test_floor_at_32(self):
+        in_w, in_h = _detection_input_size(10, 5)
+        assert in_w >= 32
+        assert in_h >= 32


 class TestBuildChangeMap:
@@ -12,12 +12,28 @@ from typing import TYPE_CHECKING

 import pytest

+from remove_ai_watermarks import trustmark_detector
 from remove_ai_watermarks.trustmark_detector import detect_trustmark, is_available

 if TYPE_CHECKING:
    from pathlib import Path


+class _FakeDecoder:
+    """A TrustMark decoder whose successive ``decode`` calls return scripted
+    ``(secret, present, schema)`` tuples -- the first for the original image, the
+    second for the re-encoded copy used by the false-positive durability gate."""
+
+    def __init__(self, *results: tuple[bytes, bool, int]):
+        self._results = list(results)
+        self.calls = 0
+
+    def decode(self, _img: object) -> tuple[bytes, bool, int]:
+        result = self._results[min(self.calls, len(self._results) - 1)]
+        self.calls += 1
+        return result
+
+
 def test_detect_never_raises(tmp_clean_png: Path):
    # Whether or not trustmark is installed, a clean image must yield None
    # (no watermark) without raising. When absent, the import guard returns None.
@@ -34,3 +50,40 @@ def test_unreadable_file_returns_none(tmp_path: Path):
 def test_clean_image_reports_no_watermark(tmp_clean_png: Path):
    # With the decoder present, an un-watermarked image must report absent.
    assert detect_trustmark(tmp_clean_png) is None
+
+
+class TestFalsePositiveGate:
+    """The re-encode durability gate keeps real (durable) TrustMarks and drops
+    BCH false positives that collapse under a mild JPEG round-trip."""
+
+    @pytest.fixture(autouse=True)
+    def _force_available(self, monkeypatch: pytest.MonkeyPatch):
+        monkeypatch.setattr(trustmark_detector, "is_available", lambda: True)
+
+    def _patch_decoder(self, monkeypatch: pytest.MonkeyPatch, decoder: _FakeDecoder) -> None:
+        monkeypatch.setattr(trustmark_detector, "_decoder", lambda: decoder)
+
+    def test_durable_watermark_survives_and_is_reported(self, monkeypatch, tmp_clean_png: Path):
+        decoder = _FakeDecoder((b"secret", True, 2), (b"secret", True, 2))
+        self._patch_decoder(monkeypatch, decoder)
+        result = detect_trustmark(tmp_clean_png)
+        assert result == "Adobe TrustMark (variant P, schema 2)"
+        assert decoder.calls == 2  # original + re-encode
+
+    def test_false_positive_collapsing_on_reencode_is_dropped(self, monkeypatch, tmp_clean_png: Path):
+        # Present on the original, absent after re-encode -> content-noise FP.
+        decoder = _FakeDecoder((b"\x00\x01", True, 3), (b"", False, -1))
+        self._patch_decoder(monkeypatch, decoder)
+        assert detect_trustmark(tmp_clean_png) is None
+
+    def test_schema_drift_on_reencode_is_dropped(self, monkeypatch, tmp_clean_png: Path):
+        # Present both times but the schema changes -> not a stable watermark.
+        decoder = _FakeDecoder((b"\x00", True, 2), (b"\x00", True, 3))
+        self._patch_decoder(monkeypatch, decoder)
+        assert detect_trustmark(tmp_clean_png) is None
+
+    def test_absent_skips_reencode(self, monkeypatch, tmp_clean_png: Path):
+        decoder = _FakeDecoder((b"", False, -1))
+        self._patch_decoder(monkeypatch, decoder)
+        assert detect_trustmark(tmp_clean_png) is None
+        assert decoder.calls == 1  # no second decode when the first is absent
@@ -0,0 +1,70 @@
+"""Tests for the known-visible-watermark registry (reverse-alpha only)."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import numpy as np
+import pytest
+
+from remove_ai_watermarks import watermark_registry as reg
+
+DOUBAO_SAMPLE = Path(__file__).resolve().parents[1] / "data" / "samples" / "doubao-1.png"
+
+
+class TestCatalog:
+    def test_keys(self):
+        assert reg.mark_keys() == ["gemini", "doubao"]
+
+    def test_all_in_auto(self):
+        assert all(m.in_auto for m in reg.known_marks())
+
+    def test_recovery_is_reverse_alpha(self):
+        # Every catalogued mark is removed by exact reverse-alpha (no inpaint).
+        assert all(m.recovery == "reverse-alpha" for m in reg.known_marks())
+
+    def test_locations(self):
+        by_key = {m.key: m for m in reg.known_marks()}
+        assert by_key["gemini"].location == "bottom-right"
+        assert by_key["doubao"].location == "bottom-right"
+
+    def test_get_mark_unknown_raises(self):
+        with pytest.raises(KeyError):
+            reg.get_mark("nope")
+
+
+class TestScan:
+    def test_detect_marks_scans_all(self):
+        img = np.zeros((256, 256, 3), np.uint8)
+        keys = {d.key for d in reg.detect_marks(img)}
+        assert keys == {"gemini", "doubao"}
+
+    def test_blank_image_no_auto_mark(self):
+        assert reg.best_auto_mark(np.zeros((256, 256, 3), np.uint8)) is None
+
+
+@pytest.mark.skipif(not DOUBAO_SAMPLE.exists(), reason="doubao sample not present")
+class TestRealSample:
+    def test_doubao_sample_wins_auto(self):
+        from remove_ai_watermarks.image_io import imread
+
+        best = reg.best_auto_mark(imread(DOUBAO_SAMPLE))
+        assert best is not None
+        assert best.key == "doubao"
+
+    def test_doubao_remove_returns_region(self):
+        from remove_ai_watermarks.image_io import imread
+
+        img = imread(DOUBAO_SAMPLE)  # 2048 wide -> reverse-alpha applies
+        result, region = reg.get_mark("doubao").remove(img)
+        assert region is not None
+        assert result.shape == img.shape
+
+
+class TestReverseAlphaOnly:
+    def test_doubao_off_resolution_is_skipped(self):
+        # No alpha capture for this width -> no inpaint fallback, image untouched.
+        img = np.zeros((512, 512, 3), np.uint8)
+        result, region = reg.get_mark("doubao").remove(img)
+        assert region is None
+        assert np.array_equal(result, img)
@@ -2865,7 +2865,7 @@ wheels = [

 [[package]]
 name = "remove-ai-watermarks"
-version = "0.6.12"
+version = "0.7.0"
 source = { editable = "." }
 dependencies = [
    { name = "click" },
Author	SHA1	Message	Date
Victor KuznetsovandClaude Opus 4.8	c928ee6e42	chore(release): v0.7.0 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>	2026-05-30 12:35:32 -07:00
Victor KuznetsovandClaude Opus 4.8	89f427852f	Fix #30 white box: stop zeroing alpha in the watermark region on save On RGBA inputs the CLI forced the watermark bbox alpha to 0 on save, so the removed-sparkle area became a transparent hole that renders as a solid white box on any non-transparent viewer. The Gemini app exports opaque RGBA, so every user hit it. Reverse-alpha already recovers the real pixels there (and `erase` inpaints them), so there is no artifact to hide -- the hole was the bug, introduced as an over-correction in `d091b9f`. `_write_bgr_with_alpha` now rejoins the input alpha plane unchanged (drops the `clear_region`/`pad` params); the `visible` / `erase` / `all` / `batch` call sites drop the cleared-region argument and the orphaned region bookkeeping. The registry `remove()` still returns the mark bbox (used for inpaint_residual positioning); the CLI just no longer clears alpha with it. Inverts the test that locked in the old behavior into a #30 regression guard (watermark-region alpha stays opaque, no pixel forced transparent). Verified end-to-end on a real Gemini RGBA export: sparkle gone, zero transparent pixels, clean over a white background. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>	2026-05-30 12:27:37 -07:00
Victor KuznetsovandClaude Opus 4.8	25a1acc53b	Detect TC260 AIGC label in JPEG EXIF and late/attribute PNG XMP A corpus audit surfaced China TC260 AIGC-labeled images that `identify` missed. Three detection gaps in `aigc_label`, all fixed: - raw-JSON `{"AIGC":{...}}` in JPEG EXIF (UserComment): brace-matched from the scan head with `json.raw_decode`, gated on a TC260 field like the PNG-chunk path. (Doubao-class output via that export surface.) - XMP attribute form `TC260:AIGC="{...}"` (PicWish): folded into the element regex as a second alternation. - TC260 XMP packet appended after a large `IDAT`, past the 1 MB scan window: `scan_head` now appends late PNG metadata chunks via `_png_late_metadata`, mirroring the existing ISOBMFF late-box scan. Adds `scripts/corpus_gap_scan.py`: runs `identify` over a corpus, writes the per-file report CSV, and flags `unknown` files that carry a known marker in their metadata region (the audit that found these gaps). Scanning only the metadata region — not the whole file — avoids the random short-token collisions inside compressed PNG/JPEG streams. On the local corpus this lifts 3 files from `unknown` to AI (China AIGC) and leaves zero false gap candidates. Synthetic piexif/PngInfo fixtures cover all three forms. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>	2026-05-30 11:44:53 -07:00
Victor KuznetsovandClaude Opus 4.8	58bdf51c59	Visible-watermark registry: reverse-alpha-only Doubao + Gemini, exact native recovery (#28 ) * fix(trustmark): gate detection on re-encode durability to kill false positives TrustMark's wm_present flag is a BCH validity check that spuriously validates on a content-correlated fraction of un-watermarked images (AI textures trip it more than camera photos). On a 1343-image set all 20 raw detections were false, several on Gemini/OpenAI/Doubao output that cannot carry Adobe's watermark, with random-bytes secrets. A genuine TrustMark is a durable soft binding that survives re-encoding, so detect_trustmark now re-decodes after a mild JPEG round-trip and requires the same schema both times. Every observed false positive collapsed under this gate; the second decode runs only on the rare hit. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * feat(identify): Samsung Galaxy AI, FLUX, ByteDance C2PA; fix C2PA substring FP Detection extensions verified on real signed files (2026-05-29): - Samsung Galaxy AI: signer attribution via a new _SIGNER_C2PA_PLATFORM (Samsung Galaxy / ASUS Gallery) kept separate from the capture-camera _DEVICE_C2PA_PLATFORM so a Galaxy AI edit (device cert + AI source type) does not trip the camera-vs-AI integrity clash. Plus metadata.samsung_genai: the proprietary genAIType marker in PhotoEditor_Re_Edit_Data, a medium- confidence AI-editing signal (samsung_only branch). - Black Forest Labs (FLUX) and ByteDance Volcano Engine (Doubao/Jimeng) added as C2PA issuers + issuer->platform mappings. - fix: C2PA presence required only the bare 4-byte 'c2pa' substring, which false-positives on compressed pixel data (a recompressed PNG IDAT re-flagged C2PA after its manifest was correctly stripped). New c2pa_marker_in() requires the JUMBF wrapper (jumb+c2pa) or the C2PA uuid box; applied in identify + metadata. Verified: all 535 real C2PA files carry jumb. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * fix(doubao): gate detection on text structure to cut ~95% of false positives (#23) Coverage alone over-fired: any textured bottom-right corner cleared the threshold, so the detector false-positived on ~28% of arbitrary images. The real '豆包AI生成' mark is six glyphs in one row, so detect now also requires the text-structure signature (_glyph_structure): many connected components, no single dominant blob, concentration in a thin horizontal band. False positives dropped 343 -> 17 across the corpus while keeping real-mark recall and the doubao-1.png sample. Also accept a no-op force kwarg for remover-interface symmetry. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * feat(samsung): add Samsung Galaxy AI visible-badge remover New samsung_engine.py removes the bottom-left sparkle + localized 'AI-generated content' badge that Galaxy AI tools stamp. Mirrors the Doubao locate->mask->inpaint pattern but bottom-left, with a dual-polarity top-hat mask (the badge is light-on-dark or dark-on-light). Detection gates on a band + left-anchor signature (the Doubao CJK-component gate does not transfer: Latin badge letters connect into few blobs). Explicit-only -- tuned on few real badges with a ~4% FP floor, so it is not used in auto. Synthetic byte-blob fixtures (real badges are user content, not shipped). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * feat(visible): unified known-watermark registry + LaMa inpaint backend watermark_registry.py is a single catalog of known visible marks, each tying {usual location, in_auto flag, recovery strategy, detect adapter, remove adapter}: gemini (reverse-alpha, exact), doubao, samsung. cmd_visible is now registry-driven (best_auto_mark for --mark auto; mark_keys() feeds the CLI choices) -- the per-mark _run_doubao/_run_samsung helper branches are gone. Cross-engine confidences are not comparable, so the gemini adapter applies the corpus-validated 0.5 sparkle threshold for auto arbitration (its engine flag is loose and weakly fired ~0.36 on Doubao text, hijacking auto). --backend auto\|cv2\|lama chooses background reconstruction for the mask-based marks; auto = LaMa when onnxruntime is present, else cv2. For LaMa the mask is the FILLED glyph bounding box (sparse glyph masks leave anti-aliased edges behind). cv2 stays the zero-dependency fallback. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * docs: watermark registry, Samsung/FLUX/ByteDance detection, LaMa backend, trustmark gate Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * feat(doubao): exact reverse-alpha removal from captured alpha map The Doubao '豆包AI生成' mark is a fixed semi-transparent white overlay, so given its alpha map the original pixels are recovered exactly: original = (wm - alogo)/(1-a) -- no inpaint hallucination. The alpha map + logo colour were solved from real black+gray Doubao captures on a controlled background: on black captured = alogo, and the black/gray pair solves a per-pixel without assuming the logo colour (a_max~0.65, logo near-white); the white capture cross-validates (mark vanishes to a flat fill). Bundled as assets/doubao_alpha.png + geometry constants. remove_watermark_reverse_alpha applies it scaled to image width; exact at the captured width, so the registry routes doubao through it only when reverse_alpha_available (width within the calibrated band) and the mark is detected, falling back to mask inpaint (cv2/LaMa) otherwise. A light residual inpaint cleans the sub-pixel rescaling error. Add captures at more resolutions to widen exact coverage. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * refactor(visible): reverse-alpha only -- drop inpaint removal + heuristic detection Per the principle that we only remove/detect what we can do exactly, the visible-mark path is now reverse-alpha only: - Doubao detect is reverse-alpha-consistent: match the bundled alpha glyph silhouette against the corner via TM_CCOEFF_NORMED (DETECT_NCC_THRESHOLD 0.4) -- keys on the '豆包AI生成' SHAPE, not coverage/structure heuristics. FP 7/1243 (0.6%). Removes the cv2 inpaint path + the _glyph_structure gate. - Registry is reverse-alpha only: dropped the cv2/LaMa backend (_glyph_remove, _lama_box_inpaint, default_backend, --backend) and the Samsung entry. Doubao outside the alpha resolution band is skipped, never inpainted. - Removed samsung_engine.py + tests + --mark samsung (no alpha map captured; Samsung C2PA/genAIType metadata detection in identify is unaffected). - The universal erase --region (cv2/LaMa) is unchanged -- arbitrary-region inpainting stays a user-directed tool, separate from the known-mark registry. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * feat(doubao): NCC sub-pixel alignment -> reverse-alpha at any resolution A pure width-scale of the captured alpha map is only sub-pixel-accurate at the captured width and leaves a faint ghost elsewhere. remove_watermark_reverse_alpha now registers the alpha glyph to the actual mark via a TM_CCOEFF_NORMED scale+position search (_aligned_alpha_map) before inverting the blend, so the single 2048 capture works at any resolution -- verified clean on the 1773x2364 (3:4) corpus size, the biggest coverage gap (23 files). reverse_alpha_available is now just 'asset present' (no width band); the registry still gates removal on detect so a clean corner is never touched. Drops the _ALPHA_WIDTH_TOLERANCE gate. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * fix(doubao): keep native recovery exact -- fixed geometry at captured width Integer-pixel NCC alignment landed ~1px off at the captured width, degrading the otherwise-exact native reverse-alpha (synthetic recovery error 0.94 -> 1.39). remove_watermark_reverse_alpha now uses exact width-relative geometry within _ALPHA_NATIVE_BAND of the captured width and the NCC search only off it -- best of both: native back to 0.94, other resolutions still aligned. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * fix(doubao): harden alignment -- try fixed+aligned, keep least residual (56/56) On a faint/busy-background mark the NCC alignment peak can wander a few px off the true mark and leave a residual (2/56 real corpus files). Off the captured width, remove_watermark_reverse_alpha now builds BOTH the fixed-geometry and the NCC-aligned alpha map, applies each, and keeps whichever leaves the least residual mark (re-detect confidence on the bare reverse-alpha) -- geometry wins on faint marks, alignment on clear ones, no magic threshold. Real-file round-trip now removes 56/56 detected Doubao clean across every corpus resolution (was 54). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * perf(doubao): skip residual inpaint at native width for exact recovery At the captured width the fixed-geometry reverse-alpha is pixel-exact, so inpainting over it only replaced exactly-recovered interior pixels with a cv2 hallucination -- measured worse on a textured background (native error vs true bg 1.6 reverse-alpha-only vs 2.6 with the old always-on full-footprint inpaint). Native now returns the bare recovery untouched; off-native, where NCC alignment is only sub-pixel-approximate, the footprint inpaint stays to clean the seam. Real round-trip still 56/56 across all corpus resolutions; negatives 0/60, Gemini unaffected. Add test_native_returns_exact_reverse_alpha_no_inpaint as the regression guard. Sync CLAUDE.md + README (the table cell and prose described the pre-NCC "skipped off native / cv2-LaMa" behavior, now stale). Gitignore the session scheduled_tasks.lock, and add the text-protection research note. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>	2026-05-29 19:49:09 -07:00
Victor KuznetsovandClaude Opus 4.8	ef6fdaeeec	Detect text at native resolution (capped), fixing small-text recall on large images (#27 ) The text-protection detector scaled every image to a fixed 736 px long side, so small text on large canvases (e.g. ~16 px on 2048) was downscaled below the detector and missed -> deformed by the SDXL pass (issue #14). Detect at the native long side capped at 1536, never upscaled (_detection_input_size, a pure unit-tested helper). Detection is script-agnostic (DB segments regions, not characters), so this is language-agnostic: a new benchmark (scripts/text_detection_benchmark.py) measures recall across Latin/Cyrillic/CJK/ Hangul/Arabic/digits x sizes x canvas -> overall hit-rate 0.91 -> 1.00, worst cell (2048/16 px) 0.06 -> 1.00. Docs updated. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>	2026-05-29 12:28:30 -07:00
xchacha20-poly1305 Claude Opus 4.8 Victor Kuznetsov	0c7ff1874e	feat(device): support xpu backend (#24 ) * feat(device): support xpu backend * Fall back to CPU seed generator when device RNG unsupported (xpu) Some torch-xpu builds have no device-side RNG, so torch.Generator(device="xpu") raises when --seed is used. _make_seed_generator tries the device generator and falls back to a backend-agnostic CPU generator. Adds a fallback unit test. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Victor Kuznetsov <kuznetsov.va@gmail.com> Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>	2026-05-29 11:13:23 -07:00
Victor KuznetsovandClaude Opus 4.8	1598c499fe	Record Doubao reverse-alpha finding: needs black-background capture, not more content images (#26 ) Session 2026-05-29: content-image reverse-alpha distillation fails (persistent ghost) because the mark is never observed on a dark background (median darkest bg over glyph pixels 58/255), so alpha is unidentifiable; no dark halo (white- logo model is right); LaMa O is a hallucination. Gemini is clean only because its map is the watermark on pure black (alpha=capture/255). Real unlock = black Doubao captures (requested in #13). Shipped direction stays mask + cv2/lama. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>	2026-05-29 11:12:58 -07:00
Victor KuznetsovandClaude Opus 4.8	a46268f6eb	Add cross-platform CI test matrix + PyPI classifiers (#25 ) * Add cross-platform CI test matrix, PyPI classifiers CI: new test.yml runs lint (ubuntu) + a test matrix (ubuntu/macos/windows x py3.10/3.12, core+dev, GPU tests skip) on push to main and PRs, closing the gap where only the release publish.yml ran (ubuntu, no tests). Add PyPI classifiers (OS/Python/topic). README Tests badge, CLAUDE.md CI note. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * Make availability tests reflect installed deps, not assume gpu extra The new core+dev CI matrix has no diffusers, so the invisible-engine availability tests (asserting is_available() is True unconditionally) and the two mocked invisible CLI tests (whose command gates on is_available before the mock) failed. Assert availability == actual importability of torch+diffusers, and patch the CLI availability gate so the mocked-engine tests run regardless of the gpu extra. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>	2026-05-29 11:04:12 -07:00