Add OpenArt visible watermark detection and removal

OpenArt.ai stamps free-plan generations with a semi-transparent white
"OpenArt" wordmark (bowtie/infinity icon + brand name) placed near the
CENTER of the frame rather than in a corner. Confirmed from a customer-
reported raiw-app production case where the mark went completely
undetected and unremoved, with no C2PA/EXIF/TC260 signal for identify
to fall back on.

- Add a new "cc" (frame-center) corner mode to the shared
  TextMarkConfig/TextMarkEngine base, alongside the existing
  corner/edge anchors.
- Add openart_engine.py, following the existing text-mark engine
  pattern. No real capture exists (OpenArt requires an account, out of
  scope to create), so the bundled alpha asset is a procedural
  reconstruction of the public logo and the NCC threshold is an
  explicitly-labeled provisional guess, not a measured calibration.
- Register the mark in watermark_registry.py, which auto-derives
  identify's platform attribution.
- Add tests/test_openart_engine.py (synthetic composites only) plus
  registry/identify test coverage, and document the mark and its
  calibration caveats in README.md, docs/supported-signals.md,
  docs/module-internals.md, and the skill's commands.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

@@ -368,7 +368,9 @@ Visible mark support includes:
   Yuanbao, Baidu, LiblibAI's bottom-center wordmark and compact top-left pill,
   and RunningHub labels;
 - one calibrated Microsoft top-right white AI-badge variant;
-- one calibrated Samsung Galaxy AI label variant.
+- one calibrated Samsung Galaxy AI label variant;
+- the OpenArt wordmark, placed at the frame center rather than a corner;
+  uncalibrated (one confirmed real case, no captured corpus).
 
 Metadata and provenance inspection covers C2PA, EXIF, XMP, IPTC, common
 generator parameters in image and video containers, China TC260 AIGC labels,

docs/module-internals.md

@@ -1603,6 +1603,61 @@ two-line mark can be light on dark scenes or dark on light scenes. Its detector
 and footprint both use the same best-match box. The separate one-line overlay
 variant is not covered.
 
+#### OpenArt wordmark
+
+Registered 2026-09-21 for a confirmed production miss reported through raiw-app:
+a free `visible`-mode run (2026-09-11, 1528x2712 portrait, Spaces uid
+`aefb1e07306f4a7280615a8daea01a39`) left a large, prominent OpenArt wordmark
+(a bowtie/infinity icon followed by "OpenArt" in bold sans-serif, semi-
+transparent white) completely unremoved -- pixel-identical before and after.
+`identify` found nothing at all for that case: no C2PA, EXIF AI tag, or China
+AIGC/TC260 label, so the visible mark is the only known attribution route for
+a bare OpenArt export. The user rated the result 0 ("Didn't work").
+
+**This is the only registered mark placed at the FRAME CENTER rather than a
+corner.** Every other engine in this family anchors to one of the four corners
+or a bottom/top edge midpoint; `_text_mark_engine.py` gained a new `"cc"`
+corner literal (both axes centered) specifically for this row, following the
+same per-vendor-measured-geometry precedent as the existing `"bc"` (LiblibAI)
+and `"tr"`/`"long"`-basis (Microsoft) additions. A frame-center locate box sits
+over far more varied image content than a corner box, which is why its NCC
+gate (0.62) is set well above Doubao/Jimeng's measured 0.45-0.50 rather than
+matching them.
+
+OpenArt (openart.ai) requires an OAuth-authenticated account for image
+generation -- there is no anonymous or API-key access (confirmed via its own
+help center and MCP/CLI docs, 2026-09-21) -- so this repository's tooling
+cannot generate a second real capture to survey placement variance by aspect
+ratio, watermark configurability, or whether a paid tier still embeds C2PA;
+only the one customer-reported case above is confirmed. OpenArt's own pricing
+page lists "Watermark-free" as a paid-plan-only feature, consistent with every
+free-plan output carrying this mark, and its help center separately confirms
+free-plan VIDEO exports carry a removable watermark toggle at download --
+independent evidence that a visible free-tier watermark is real product
+behavior, not one-off.
+
+Unlike every captured brand mark in this file, there is no committed real
+capture to solve an alpha map from (see above -- no account access) and no
+public example image was reconstructed by hand. `scripts/build_openart_alpha.py`
+instead PROCEDURALLY DRAWS a reconstruction of OpenArt's own public brand mark
+(the bowtie icon + wordmark shown on openart.ai's own marketing pages) as a
+grayscale alpha PNG, the same bundled-asset contract every other engine uses.
+
+**CALIBRATION IS PROVISIONAL, NOT MEASURED.** There is no recall/precision
+sweep like Doubao's or the generic-label engine's: no positive corpus exists
+at all beyond the one production case, real or synthetic-composited. The 0.62
+NCC threshold is a conservative guess, not a measured operating point; a quick
+false-fire check against 15 random Gaussian-blurred noise images at plausible
+aspect ratios and sizes found zero false fires, which is reassurance, not
+calibration. Do not cite this mark in any auto-scan precision claim, and do
+not lower its threshold, without a real captured corpus under
+`data/calibration/openart/`.
+
+`openart_engine.py`'s module docstring carries the same caveats in code. Its
+tests (`tests/test_openart_engine.py`) mirror `test_doubao_engine.py`'s
+structure entirely on synthetic composites of the bundled asset -- there is no
+`TestRealSample` analogue.
+
 #### Bare-upload pill arm: measured impossible with the current detector (2026-08-28)
 
 `_keep_pill` never removes a metadata-bare pill, and the question "can a bare arm

docs/supported-signals.md

@@ -23,6 +23,7 @@ The `visible` command registers these mark keys:
 | `liblib_pill` | Compact `AI生成` pill | Top left | Auto removal requires LiblibAI metadata or the bottom-center wordmark, plus a flat background under the pill. |
 | `microsoft` | One Microsoft white AI-badge variant | Top right | Strict uses the visual gate; auto can use Microsoft provenance for the measured [relaxed gate](module-internals.md#visible-mark-removal). Other documented icon, text, and position variants are not covered. |
 | `jimeng_pill` | `AI生成` pill | Top left | Weak detector with additional product and background gates. |
+| `openart` | `OpenArt` wordmark (bowtie/infinity icon + brand name) | Frame center, not a corner | Confirmed from one customer-reported production case; no known metadata signal, so the visible mark is the only attribution route. **UNCALIBRATED**: procedurally reconstructed asset, no captured corpus -- see [module-internals.md](module-internals.md#openart-wordmark). |
 
 `--mark auto` evaluates all registered marks and removes every selected match.
 Known marks are localized to a mask, then the selected fill backend reconstructs

scripts/build_openart_alpha.py

@@ -0,0 +1,93 @@
+"""Build the PROVISIONAL synthetic OpenArt alpha asset.
+
+Unlike ``visible_alpha_solve.py``, this does NOT recover an alpha map from a
+controlled capture: OpenArt (openart.ai) requires an account to generate
+images (no anonymous or API-key access, confirmed 2026-09-21 via its own
+help center and MCP docs), and creating an account is outside what this
+project's tooling is allowed to do on its own. No committed capture exists
+under ``data/calibration/openart/``.
+
+This script instead PROCEDURALLY DRAWS a reconstruction of OpenArt's own
+brand mark (the bowtie/infinity icon followed by the "OpenArt" wordmark, as
+shown on openart.ai's own marketing pages) as a semi-transparent white
+overlay, matching the general rendering style (near-white, low-saturation,
+anti-aliased) that every other bundled text-mark asset in this module was
+solved from. It is a reconstruction from the public logo, not a recovered
+watermark alpha map, and ``openart_engine.py`` documents that provenance
+gap explicitly. Replace this asset (and re-run the engine's calibration)
+the moment a real captured OpenArt export is available under
+``data/calibration/openart/``.
+
+Usage::
+
+    uv run python scripts/build_openart_alpha.py
+"""
+
+# cv2/numpy boundary: third-party libs ship no usable element types; relax the
+# unknown-type rules for this file only (mirrors visible_alpha_solve.py).
+# pyright: reportUnknownMemberType=false, reportUnknownArgumentType=false, reportUnknownVariableType=false, reportUnknownParameterType=false, reportMissingTypeArgument=false, reportMissingTypeStubs=false, reportMissingImports=false, reportArgumentType=false, reportAssignmentType=false, reportReturnType=false, reportCallIssue=false, reportIndexIssue=false, reportOperatorIssue=false
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+
+import cv2
+import numpy as np
+
+sys.path.insert(0, str(Path(__file__).parent.parent))
+
+_ROOT = Path(__file__).resolve().parents[1]
+_ASSET = _ROOT / "src" / "remove_ai_watermarks" / "assets" / "openart_alpha.png"
+
+# Canvas sized to comfortably fit "OpenArt" set bold at this height plus the
+# icon and inter-glyph gap, at a resolution close to the other bundled
+# assets (doubao_alpha.png is 335x83).
+_W, _H = 360, 90
+_ALPHA_PEAK = 173  # matches doubao_alpha.png's measured peak (~68% opacity)
+
+
+def _draw_infinity_icon(canvas: np.ndarray, cx: int, cy: int, size: int) -> None:
+    """Draw the bowtie/infinity glyph left of the wordmark (two mirrored lobes)."""
+    half = size // 2
+    # Two overlapping filled triangles meeting at the center, echoing the
+    # angular "infinity" mark on openart.ai's own site header.
+    left_lobe = np.array(
+        [[cx - size, cy - half], [cx - size, cy + half], [cx, cy]],
+        dtype=np.int32,
+    )
+    right_lobe = np.array(
+        [[cx + size, cy - half], [cx + size, cy + half], [cx, cy]],
+        dtype=np.int32,
+    )
+    cv2.fillConvexPoly(canvas, left_lobe, (_ALPHA_PEAK,), lineType=cv2.LINE_AA)
+    cv2.fillConvexPoly(canvas, right_lobe, (_ALPHA_PEAK,), lineType=cv2.LINE_AA)
+
+
+def build() -> np.ndarray:
+    canvas = np.zeros((_H, _W), np.uint8)
+    icon_cx, icon_cy, icon_size = 34, _H // 2, 22
+    _draw_infinity_icon(canvas, icon_cx, icon_cy, icon_size)
+
+    text_x = icon_cx + icon_size + 18
+    cv2.putText(
+        canvas,
+        "OpenArt",
+        (text_x, _H // 2 + 16),
+        cv2.FONT_HERSHEY_DUPLEX,
+        1.3,
+        (_ALPHA_PEAK,),
+        thickness=2,
+        lineType=cv2.LINE_AA,
+    )
+    return canvas
+
+
+def main() -> None:
+    canvas = build()
+    _ASSET.parent.mkdir(parents=True, exist_ok=True)
+    cv2.imwrite(str(_ASSET), canvas)
+    print(f"Wrote {_ASSET} ({canvas.shape[1]}x{canvas.shape[0]}, peak={int(canvas.max())})")
+
+
+if __name__ == "__main__":
+    main()

skills/remove-ai-watermarks/references/commands.md

@@ -22,12 +22,14 @@ remove-ai-watermarks visible image.png --keep-metadata -o clean.png
 
 Image mark keys: `gemini`, `doubao`, `jimeng`, `qwen`, `kling`, `yuanbao`,
 `samsung`, `runninghub`, `baidu`, `liblib`, `liblib_pill`, `microsoft`,
-`jimeng_pill`. Default
+`openart`, `jimeng_pill`. Default
 `--mark auto` removes every selected match. `microsoft` is the top-right AI
 badge, separate from the invisible InvisMark watermark on the same vendor's
 images. `jimeng_pill` is a weak detector and needs corroboration. The compact
 `liblib_pill` likewise requires LiblibAI metadata or the bottom-center wordmark
-(since CLI 0.39.0).
+(since CLI 0.39.0). `openart` sits
+in the FRAME CENTER, not a corner, and is UNCALIBRATED (one confirmed real
+case, no captured corpus) -- see `openart_engine.py`'s module docstring.
 
 ```bash
 remove-ai-watermarks erase image.png --region 1640,1930,400,100 -o clean.png

src/remove_ai_watermarks/_text_mark_engine.py

@@ -89,8 +89,8 @@ class TextMarkConfig:
     name: str  # short label for log lines (e.g. "Doubao")
     asset_name: str  # bundled alpha PNG under assets/ (e.g. "doubao_alpha.png")
     corner: Literal[
-        "br", "bl", "tl", "tr", "bc"
-    ]  # br (Doubao/Jimeng), bl (Samsung), tl (RunningHub), tr (Microsoft), bc (LiblibAI)
+        "br", "bl", "tl", "tr", "bc", "cc"
+    ]  # br (Doubao/Jimeng), bl (Samsung), tl (RunningHub), tr (Microsoft), bc (LiblibAI), cc (OpenArt)
     margin_floor: int  # min margin in px for locate (4 for br marks, 2 for Samsung)
     # locate geometry (fraction of scale_base -- see scale_base())
     width_frac: float
@@ -528,12 +528,17 @@ class TextMarkEngine:
         margin_b = max(c.margin_floor, int(base * c.margin_bottom_frac))
         if c.corner == "br" or c.corner == "tr":
             x = max(0, w - margin_x - wm_w)
-        elif c.corner == "bc":  # bottom-center: horizontally centered, margin_x unused
+        elif c.corner in ("bc", "cc"):  # horizontally centered, margin_x unused
             x = max(0, (w - wm_w) // 2)
         else:
             x = min(margin_x, max(0, w - wm_w))
         # "tl"/"tr" anchor at the top instead: margin_bottom_frac is then the TOP margin.
-        y = min(margin_b, max(0, h - wm_h)) if c.corner in ("tl", "tr") else max(0, h - margin_b - wm_h)
+        if c.corner in ("tl", "tr"):
+            y = min(margin_b, max(0, h - wm_h))
+        elif c.corner == "cc":  # frame-center: vertically centered, margin_bottom_frac unused
+            y = max(0, (h - wm_h) // 2)
+        else:
+            y = max(0, h - margin_b - wm_h)
         wm_w = min(wm_w, w - x)
         wm_h = min(wm_h, h - y)
         return TextMarkLocation(x=x, y=y, w=wm_w, h=wm_h)

src/remove_ai_watermarks/openart_engine.py

@@ -0,0 +1,141 @@
+"""OpenArt visible watermark detector/localizer.
+
+OpenArt (openart.ai) stamps free-plan generations with a semi-transparent white
+"OpenArt" wordmark (a bowtie/infinity icon followed by the brand name) placed
+**near the center of the frame**, not in a corner like every other text mark
+this repository detects. Confirmed from one customer-reported production case
+(raiw-app, 2026-09-11, 1528x2712 portrait output): the mark sat roughly centered
+over the subject's torso, and neither C2PA, EXIF AI tags, nor the China AIGC/TC260
+label were present -- OpenArt apparently ships no machine-readable provenance
+signal alongside this visible mark, so a bare export was previously reported as
+``platform: null`` with zero signals. OpenArt's own pricing page lists
+"Watermark-free" as a paid-plan feature, consistent with every free-plan output
+carrying this mark; its help center separately confirms free-plan video exports
+carry a removable watermark toggle. No independent confirmation of placement
+variance by aspect ratio, of a configurable/opt-out watermark on free tier, or
+of a paid tier that still embeds C2PA/other metadata is available -- OpenArt
+requires an account for image generation (no anonymous or API access), so this
+was not surveyed across multiple generations.
+
+**Calibration is PROVISIONAL, not measured.** Every other engine in this module
+ships a recall/precision table from tens to hundreds of hand-labeled real
+captures (see ``doubao_engine.py``). No such corpus exists for OpenArt: there is
+no committed real capture (see ``scripts/build_openart_alpha.py`` for why), so
+``DETECT_NCC_THRESHOLD`` below is set conservatively high rather than measured,
+specifically because a center-frame locate box (see ``_text_mark_engine.corner
+== "cc"``) sits over far more varied image content than a corner box, and an
+uncalibrated false-fire there destroys pixels in the middle of the photo. Do
+not lower this threshold or add OpenArt to any auto-scan precision claim
+without a real measured corpus under ``data/calibration/openart/``.
+
+Detection matches the bundled (procedurally reconstructed, not captured)
+glyph silhouette against the center-frame candidate; removal is the shared
+**localize -> fill**, using the default template-free rectangular footprint
+(no override -- unlike Doubao, this mark does not sit near a frame edge where
+a solid rectangular fill risks bleeding into un-inpaintable border texture).
+This module shares :class:`remove_ai_watermarks._text_mark_engine.TextMarkEngine`
+and supplies only OpenArt's tuned :class:`TextMarkConfig`.
+"""
+
+# pyright: reportUnusedFunction=false
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+
+from remove_ai_watermarks import _text_mark_engine
+from remove_ai_watermarks._text_mark_engine import TextMarkConfig, TextMarkEngine
+
+if TYPE_CHECKING:
+    from numpy.typing import NDArray
+
+# Locate geometry as a fraction of the image SHORT side (portrait is the only
+# observed carrier so far; "short" keeps the box a sane size on landscape
+# inputs too, mirroring Doubao's rationale -- see scale_base). Generously
+# oversized relative to the alpha template below so the scale ladder and NCC
+# alignment search both have slack; unlike a corner mark this box floats free
+# in the frame, so accuracy depends entirely on the NCC score, not the corner
+# anchor.
+WM_WIDTH_FRAC = 0.55
+WM_HEIGHT_FRAC = 0.18
+MARGIN_X_FRAC = 0.0  # unused: "cc" centers horizontally regardless of margin_x_frac
+MARGIN_BOTTOM_FRAC = 0.0  # unused: "cc" centers vertically regardless of margin_bottom_frac
+
+# Glyph appearance: a light, low-saturation near-white overlay (white top-hat),
+# the same rendering class as every other bundled text mark.
+MAX_SATURATION = 55
+LOGO_MIN_LUMA = 150
+TOPHAT_DELTA = 12
+
+# Inert for the "tophat" front-end (see _text_mark_engine._scan: the coverage
+# gate only guards the "binary" front-end), kept for the dataclass contract.
+DETECT_MIN_COVERAGE = 0.02
+
+# UNCALIBRATED -- see module docstring. Set well above Doubao/Jimeng's measured
+# 0.45-0.50 specifically because this mark floats in the frame center rather
+# than a corner, where an unrelated bright/textured subject is far more likely
+# to produce an incidental top-hat blob than in a corner. Re-measure against a
+# real captured corpus before relying on this number for a precision claim.
+DETECT_NCC_THRESHOLD = 0.62
+
+# No independent provenance signal is known for OpenArt (see module docstring),
+# so the provenance-relaxed gate can never be legitimately reached today; keep
+# it at parity with the strict gate rather than inventing a relaxation factor
+# with nothing to calibrate it against.
+PROVENANCE_NCC_FACTOR = 1.0
+
+# Detection-silhouette geometry for the bundled (procedurally reconstructed)
+# asset -- see scripts/build_openart_alpha.py. The asset canvas is 360x90
+# (aspect ~4:1). Unlike a solved capture, there is no real photo resolution to
+# anchor this to, so _ALPHA_NATIVE_WIDTH is simply the round basis the asset's
+# own fractions are self-consistent against (360/1024 and 90/1024): at
+# scale_base == _ALPHA_NATIVE_WIDTH the resized template comes back at the
+# asset's own native pixel size.
+_ALPHA_NATIVE_WIDTH = 1024
+_ALPHA_WIDTH_FRAC = 360 / 1024
+_ALPHA_HEIGHT_FRAC = 90 / 1024
+
+_CONFIG = TextMarkConfig(
+    name="OpenArt",
+    asset_name="openart_alpha.png",
+    corner="cc",
+    margin_floor=4,
+    width_frac=WM_WIDTH_FRAC,
+    height_frac=WM_HEIGHT_FRAC,
+    margin_x_frac=MARGIN_X_FRAC,
+    margin_bottom_frac=MARGIN_BOTTOM_FRAC,
+    max_saturation=MAX_SATURATION,
+    logo_min_luma=LOGO_MIN_LUMA,
+    tophat_delta=TOPHAT_DELTA,
+    morph_open_size=5,
+    detect_min_coverage=DETECT_MIN_COVERAGE,
+    detect_ncc_threshold=DETECT_NCC_THRESHOLD,
+    provenance_ncc_factor=PROVENANCE_NCC_FACTOR,
+    detect_frontend="tophat",
+    scale_basis="short",
+    alpha_width_frac=_ALPHA_WIDTH_FRAC,
+    alpha_height_frac=_ALPHA_HEIGHT_FRAC,
+    min_gw=12,
+)
+
+
+def _alpha_template() -> NDArray[Any] | None:
+    """The bundled (procedurally reconstructed) OpenArt alpha template (float [0,1]), or None."""
+    return _text_mark_engine.load_alpha_template(_CONFIG.asset_name)
+
+
+def _glyph_silhouette() -> NDArray[Any] | None:
+    """Binary "OpenArt" wordmark silhouette (255 = glyph) from the alpha map, or None."""
+    return _text_mark_engine.glyph_silhouette(_CONFIG.asset_name)
+
+
+def _template_match_score(box_mask: NDArray[Any], scale_base: int) -> float:
+    """TM_CCOEFF_NORMED of the OpenArt glyph silhouette against ``box_mask``."""
+    return _text_mark_engine.template_match_score(box_mask, scale_base, _CONFIG)
+
+
+class OpenArtEngine(TextMarkEngine):
+    """Detect/localize the visible, center-frame OpenArt wordmark (locate -> mask; mask feeds the fill)."""
+
+    def __init__(self) -> None:
+        super().__init__(_CONFIG)

src/remove_ai_watermarks/watermark_registry.py

@@ -31,6 +31,9 @@ Entries:
   - ``liblib`` -- LiblibAI "LiblibAI" wordmark, bottom-center.
   - ``liblib_pill`` -- LiblibAI compact "AI生成" pill, top-left.
   - ``microsoft`` -- one measured Microsoft white AI-badge variant, top-right.
+  - ``openart`` -- OpenArt "OpenArt" wordmark (bowtie/infinity icon + brand name),
+    frame-center; UNCALIBRATED (one confirmed real case, no captured corpus), see
+    ``openart_engine.py``.
 """
 
 from __future__ import annotations
@@ -450,6 +453,7 @@ _ENGINE_CLASS: dict[str, tuple[str, str]] = {
     "liblib": ("liblib_engine", "LibLibEngine"),
     "liblib_pill": ("liblib_engine", "LibLibPillEngine"),
     "microsoft": ("microsoft_engine", "MicrosoftEngine"),
+    "openart": ("openart_engine", "OpenArtEngine"),
 }
 
 
@@ -786,6 +790,20 @@ _REGISTRY: tuple[KnownMark, ...] = (
         platform="Microsoft (visible top-right AI badge detected)",
         provenance_platform_tokens=("microsoft",),
     ),
+    # Frame-center, not a corner -- see the "cc" corner and openart_engine.py's module
+    # docstring for the single confirmed carrier and why this row is UNCALIBRATED.
+    # No China TC260 label and no other known metadata signal: label_regime=None,
+    # provenance_signals=() mirror Microsoft's non-attributable-device shape rather
+    # than the TC260 default every other _text_mark row above inherits.
+    _text_mark(
+        "openart",
+        "OpenArt wordmark",
+        "frame-center",
+        platform="OpenArt (visible OpenArt mark detected)",
+        manufacturer="openart",
+        label_regime=None,
+        provenance_signals=(),
+    ),
     # Same product as the Jimeng wordmark -- the one pair that cross-relaxes.
     KnownMark(
         "jimeng_pill",

tests/test_identify.py

@@ -1212,6 +1212,21 @@ class TestIdentifyVisibleTextMarks:
         assert "Jimeng" in r.platform
         assert any(s.name == "visible_jimeng" for s in r.signals)
 
+    def test_openart_promotes_to_medium(self, tmp_clean_png: Path):
+        """OpenArt has no known TC260/C2PA/EXIF signal (see openart_engine.py's
+        module docstring), so the visible mark is the ONLY route to a platform
+        attribution -- this is the exact production gap the mark closes: a bare
+        OpenArt export previously reported `platform: null` with zero signals."""
+        det = self._detection("openart", "OpenArt wordmark", 0.85)
+        with patch(_SPARKLE_TARGET, return_value=None), patch(_TEXT_MARKS_TARGET, return_value=[det]):
+            r = identify(tmp_clean_png, check_visible=True)
+        assert r.is_ai_generated is True
+        assert r.confidence == "medium"
+        assert r.platform is not None
+        assert "OpenArt" in r.platform
+        signal = next(s for s in r.signals if s.name == "visible_openart")
+        assert signal.confidence == "medium"
+
     def test_check_visible_false_skips_text_marks(self, tmp_clean_png: Path):
         det = self._detection("doubao", "Doubao 豆包AI生成 text", 0.99)
         with patch(_SPARKLE_TARGET, return_value=None), patch(_TEXT_MARKS_TARGET, return_value=[det]) as mock:

tests/test_openart_engine.py

@@ -0,0 +1,205 @@
+"""Tests for the OpenArt visible-watermark engine (localize -> fill).
+
+No real captured OpenArt sample is committed (see ``openart_engine.py``'s module
+docstring for why), so every fixture here is a synthetic composite of the
+bundled, procedurally reconstructed alpha asset -- there is no
+``TestRealSample`` analogue to ``test_doubao_engine.py``'s skip-if-absent class.
+"""
+
+from __future__ import annotations
+
+import cv2
+import numpy as np
+import pytest
+
+from remove_ai_watermarks import watermark_registry as registry
+from remove_ai_watermarks.openart_engine import (
+    _ALPHA_HEIGHT_FRAC,
+    _ALPHA_NATIVE_WIDTH,
+    _ALPHA_WIDTH_FRAC,
+    DETECT_NCC_THRESHOLD,
+    OpenArtEngine,
+    _alpha_template,
+    _glyph_silhouette,
+    _template_match_score,
+)
+
+
+def _compose(w: int, h: int, bg: float = 100.0):
+    """Composite the bundled alpha (scaled to the image's short side) onto a flat
+    bg, centered in the frame. Returns ``(watermarked_uint8, mark_bool_mask)``."""
+    img = np.full((h, w, 3), bg, np.float32)
+    at = _alpha_template()
+    base = min(w, h)
+    gw, gh = int(_ALPHA_WIDTH_FRAC * base), int(_ALPHA_HEIGHT_FRAC * base)
+    ax = (w - gw) // 2
+    ay = (h - gh) // 2
+    amap = np.zeros((h, w), np.float32)
+    amap[ay : ay + gh, ax : ax + gw] = cv2.resize(at, (gw, gh))
+    a3 = amap[:, :, None]
+    wm = (a3 * 255.0 + (1 - a3) * img).clip(0, 255).astype(np.uint8)
+    return wm, amap > 0.2
+
+
+class TestLocate:
+    def test_box_centered_in_frame(self):
+        eng = OpenArtEngine()
+        img = np.zeros((2048, 2048, 3), np.uint8)
+        loc = eng.locate(img)
+        cx, cy = loc.x + loc.w / 2, loc.y + loc.h / 2
+        assert cx == pytest.approx(2048 / 2, abs=2048 * 0.02)
+        assert cy == pytest.approx(2048 / 2, abs=2048 * 0.02)
+
+    def test_box_scales_with_short_side(self):
+        eng = OpenArtEngine()
+        small = eng.locate(np.zeros((1024, 1024, 3), np.uint8))
+        large = eng.locate(np.zeros((2048, 2048, 3), np.uint8))
+        assert large.w == pytest.approx(small.w * 2, rel=0.1)
+
+    def test_box_stays_centered_on_portrait(self):
+        """The one confirmed carrier is a portrait (1528x2712); the box must stay
+        horizontally AND vertically centered, not just anchored to one axis."""
+        eng = OpenArtEngine()
+        loc = eng.locate(np.zeros((2712, 1528, 3), np.uint8))
+        cx, cy = loc.x + loc.w / 2, loc.y + loc.h / 2
+        assert cx == pytest.approx(1528 / 2, abs=1528 * 0.02)
+        assert cy == pytest.approx(2712 / 2, abs=2712 * 0.02)
+
+
+class TestDetect:
+    def test_clean_gradient_not_detected(self):
+        eng = OpenArtEngine()
+        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_center_not_detected(self):
+        """A bright blob is not the glyph shape -> low correlation, not detected."""
+        eng = OpenArtEngine()
+        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 = 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
+        solid = np.full_like(box, 255)
+        assert _template_match_score(solid, _ALPHA_NATIVE_WIDTH) < DETECT_NCC_THRESHOLD
+
+    def test_small_image_guarded_from_false_positive(self):
+        """Below the shared minimum short side, detection is skipped outright
+        (``_MIN_DETECT_SHORT_SIDE`` in ``_text_mark_engine``) regardless of vendor."""
+        wm, _mark = _compose(_ALPHA_NATIVE_WIDTH, _ALPHA_NATIVE_WIDTH)
+        eng = OpenArtEngine()
+        assert eng.detect(wm).detected  # native: synthetic mark detected
+        assert not eng.detect(cv2.resize(wm, (150, 150))).detected  # below guard: suppressed
+
+    def test_random_textured_images_do_not_false_fire(self):
+        """A frame-center locate box sits over far more varied content than a
+        corner box (see the module docstring's calibration caveat); guard against
+        the obvious failure mode on plain photographic texture."""
+        eng = OpenArtEngine()
+        rng = np.random.default_rng(0)
+        for _ in range(15):
+            h, w = int(rng.integers(1000, 2200)), int(rng.integers(1000, 2200))
+            noise = rng.integers(60, 200, (h, w, 3)).astype(np.uint8)
+            img = cv2.GaussianBlur(noise, (0, 0), sigmaX=8)
+            assert not eng.detect(img).detected
+
+
+class TestAlphaAsset:
+    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
+
+
+class TestFootprintMaskAndRemoval:
+    def test_footprint_mask_near_frame_center(self):
+        wm, _mark = _compose(_ALPHA_NATIVE_WIDTH, _ALPHA_NATIVE_WIDTH)
+        mask = OpenArtEngine().footprint_mask(wm)
+        assert mask is not None
+        assert mask.shape == wm.shape[:2]
+        ys, xs = np.where(mask > 0)
+        assert ys.mean() == pytest.approx(wm.shape[0] / 2, abs=wm.shape[0] * 0.15)
+        assert xs.mean() == pytest.approx(wm.shape[1] / 2, abs=wm.shape[1] * 0.15)
+
+    def test_removes_synthetic_mark(self):
+        wm, _mark = _compose(_ALPHA_NATIVE_WIDTH, _ALPHA_NATIVE_WIDTH)
+        assert OpenArtEngine().detect(wm).detected
+        out, region = registry.get_mark("openart").remove(wm, backend="cv2")
+        assert region is not None
+        assert not OpenArtEngine().detect(out).detected
+
+    @pytest.mark.parametrize(
+        ("w", "h"),
+        [
+            (_ALPHA_NATIVE_WIDTH, _ALPHA_NATIVE_WIDTH),  # square
+            (1528, 2712),  # the one confirmed carrier's exact aspect/size
+        ],
+    )
+    def test_fill_removes_and_leaves_frame_edges(self, w, h):
+        """The fill lowers re-detect confidence and leaves the untouched corners exact."""
+        wm, mark = _compose(w, h)
+        assert float(np.abs(wm.astype(np.float32)[mark] - 100.0).mean()) > 15  # mark visible
+        before = OpenArtEngine().detect(wm)
+        out, _ = registry.get_mark("openart").remove(wm, backend="cv2")
+        assert OpenArtEngine().detect(out).confidence < before.confidence
+        edge = max(4, min(w, h) // 8)
+        assert np.array_equal(out[:edge, :edge], wm[:edge, :edge])
+        assert np.array_equal(out[-edge:, -edge:], wm[-edge:, -edge:])
+
+
+class TestDegenerateAndChannelInputs:
+    """footprint_mask must not crash on degenerate sizes or non-3-channel inputs."""
+
+    @pytest.mark.parametrize(("w", "h"), [(2048, 1), (1, 2048), (2048, 8)])
+    def test_wide_short_does_not_raise(self, w, h):
+        eng = OpenArtEngine()
+        img = np.zeros((h, w, 3), np.uint8)
+        mask = eng.footprint_mask(img, force=True)
+        assert mask is None or mask.shape == (h, w)
+
+    def test_grayscale_2d_does_not_raise(self):
+        eng = OpenArtEngine()
+        gray = np.zeros((2048, 2048), np.uint8)
+        mask = eng.footprint_mask(gray, force=True)
+        assert mask is None or mask.shape == (2048, 2048)
+
+    def test_bgra_4channel_does_not_raise(self):
+        eng = OpenArtEngine()
+        bgra = np.zeros((2048, 2048, 4), np.uint8)
+        mask = eng.footprint_mask(bgra, force=True)
+        assert mask is None or mask.shape == (2048, 2048)
+
+    @pytest.mark.parametrize("shape", [(20, 20, 3), (10, 400, 3), (400, 10, 3), (1, 1, 3), (2000, 2000, 3)])
+    def test_locate_box_stays_in_bounds(self, shape):
+        """locate() must clamp its geometry box inside the image for ANY size/aspect,
+        including the frame-center ("cc") corner -- alongside br/bl as in Doubao's test."""
+        from remove_ai_watermarks._text_mark_engine import TextMarkEngine
+        from remove_ai_watermarks.doubao_engine import _CONFIG as BR_CONFIG
+        from remove_ai_watermarks.openart_engine import _CONFIG as CC_CONFIG
+        from remove_ai_watermarks.samsung_engine import _CONFIG as BL_CONFIG
+
+        h, w = shape[:2]
+        img = np.zeros(shape, np.uint8)
+        for cfg in (BR_CONFIG, BL_CONFIG, CC_CONFIG):
+            loc = TextMarkEngine(cfg).locate(img)
+            assert loc.x >= 0
+            assert loc.y >= 0
+            assert loc.x + loc.w <= w
+            assert loc.y + loc.h <= h
+            assert loc.w > 0
+            assert loc.h > 0

tests/test_watermark_registry.py

@@ -27,6 +27,7 @@ class TestCatalog:
             "liblib",
             "liblib_pill",
             "microsoft",
+            "openart",
             "jimeng_pill",
         ]
 
@@ -49,6 +50,7 @@ class TestCatalog:
         assert by_key["samsung"].location == "bottom-left"
         assert by_key["liblib_pill"].location == "top-left"
         assert by_key["jimeng_pill"].location == "top-left"
+        assert by_key["openart"].location == "frame-center"
 
     def test_get_mark_unknown_raises(self):
         with pytest.raises(KeyError):
@@ -118,6 +120,7 @@ class TestScan:
             "liblib",
             "liblib_pill",
             "microsoft",
+            "openart",
             "jimeng_pill",
         }