Victor Kuznetsov
e572767555
Visible-watermark work across all three corner-mark engines plus a committed,
reproducible alpha-build pipeline (scripts/visible_alpha_solve.py) fed by committed
solid black/gray/white captures.
- jimeng: new "即梦AI" wordmark remover (reverse-alpha + thin residual inpaint,
always NCC-aligned -- the mark re-rasterizes/jitters per image). Detect via glyph
silhouette NCC (0.45 threshold; does not cross-fire with Doubao). Registered in the
visible-mark catalog; `visible --mark jimeng` / `--mark auto`.
- doubao: fix a real production defect -- the shipped remover left a READABLE
"豆包AI生成" outline on real samples while detect() returned conf 0.0 (fooled by a
thin outline), so the test passed and the "56/56 clean" claim was detector-measured,
not visual. Root cause: under-estimated alpha + fixed-geometry-no-inpaint + tight
locate box. Rebuilt alpha (careful gray-self solve), always-align, thin inpaint,
widened locate box -> readable outline becomes faint texture-level traces.
- gemini: rebuild gemini_bg_{96,48} from our own controlled captures (validated NCC
0.9998 vs the prior third-party asset); removal re-verified clean, no behaviour change.
- tests: add textured-shift regression to both engines (guards the align-on-shift path
the Doubao defect exposed; lesson: a detector-only removal test is insufficient,
assert visual residual).
- docs: CLAUDE.md, README, capture READMEs and docstrings synced; stale
"exact/pixel-exact/56-clean" claims removed.
Also includes a SynthID label-wording clarification in identify.py/cli.py
("SynthID pixel watermark" -> "SynthID watermark, inferred from C2PA metadata").
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
4.6 KiB
Doubao visible watermark capture
Status (captured 2026-05-29; alpha rebuilt 2026-05-31): the black/gray/white captures were taken and are now committed in
captures/(solid colour + watermark, content-free). The alpha map is rebuilt byscripts/visible_alpha_solve.py doubao(the careful gray-self solve shared with Jimeng). The first build claimed "pixel-exact" but left a readable outline on the real sample (issue #13 follow-up); removal now reverse-alphas, NCC-aligns, and applies a thin residual inpaint. See thedoubao_engine.pynotes in the rootCLAUDE.md. The text below is kept as the historical capture plan.
Goal: capture the Doubao "豆包AI生成" visible watermark over known flat backgrounds so we can
build a per-pixel alpha map and a reverse-alpha-blend remover, the same way the Gemini sparkle
engine works (src/remove_ai_watermarks/gemini_engine.py).
What we already know (verified from prior art, 2026-05-26)
- Blend model: alpha compositing with a white logo
watermarked = a*logo + (1-a)*original,logo = (255,255,255). Inversion:original = (watermarked - a*logo) / (1-a). Confirmed by two independent sources (an open-source remover's algorithm doc + aiwatermarkremover.dev, both say "alpha map"). One commercial blog (pixelcleanai) claims "screen blend" instead; the gray capture below settles it empirically. - Position: bottom-right corner, small margins (right ~8-20px, bottom ~5px), scales with image size.
Confirmed by our sample
data/samples/doubao-1.png(2048x2048) plus three sources. - Size scales with resolution. Third-party numbers (~90x18 at <=1024, ~180x40 at >1024) are approximate and calibrated for ~1024-1280 outputs; at 2048 the strip is much larger. A shipped third-party alpha map is only 120x20, too small for our 2K/4K target -> capture fresh.
- The planning assumption was that clean inversion leaves residue on textured backgrounds, so the remover would pair the alpha map with inpainting. After the capture this turned out unnecessary at the native width (recovery is pixel-exact there and inpaint is off); the shipped remover is reverse-alpha only, with a residual inpaint applied off-native only.
Use doubao.com specifically
The "豆包AI生成" mark is Doubao's. Jimeng / Dreamina use a different mark. Generate on doubao.com so the captured template matches our target.
How to capture (image-edit path, most reliable)
For each seed in seeds/:
- Open Doubao image generation, use the image-edit / reference mode, upload the seed.
- Prompt (Chinese preferred):
请完全按照原图重新生成这张图片，保持完全一致，不要添加或修改任何内容(English:Recreate this image exactly as it is, keep it identical, do not add or change anything) - Download the ORIGINAL output file (not a screenshot). Do not crop / edit / re-save.
Prior art confirms uploading a pure-black image and letting Doubao stamp it works.
If edit mode is unavailable and text-to-image refuses a solid color, fall back to generating 10-12 normal-content images at one fixed resolution; the mark is the only constant across them and can be extracted by per-pixel min/median.
What to capture (priority top to bottom)
| Aspect | black | white | gray128 | why |
|---|---|---|---|---|
| 1:1 | 3 | 1 | 1 | primary alpha map + confirm the stamp is pixel-identical across runs + settle blend mode |
| 16:9 | 2 | 1 | 1 | anchor rule in landscape |
| 9:16 | 2 | 1 | 1 | anchor rule in portrait |
| 4:3, 3:4 | 1 each | - | - | optional, refines anchor rule |
- 3 blacks on 1:1: if the first two are byte-identical in the watermark region, the third is optional.
- gray128 is the blend-mode test: predict the gray result from the black capture under alpha vs screen; whichever matches the real gray output is the true blend.
- If the UI offers multiple output resolutions (1K / 2K / 4K), capture one black per resolution on 1:1 - needed to learn how the watermark scales.
- Also grab 3-5 normal-content images on 1:1 for end-to-end removal validation.
Hygiene
- Original download, never a screenshot. PNG preferred; if Doubao only gives JPEG, note it.
- No crop / edit / re-save. Default settings, watermark left ON.
Naming, drop into captures/
doubao_black_1x1_1.png
doubao_white_1x1_1.png
doubao_gray128_1x1_1.png
doubao_black_16x9_1.png
doubao_content_1x1_1.png
Also report back
- Which resolutions and aspect ratios the Doubao UI actually offers.
- Whether there is a watermark on/off toggle in the UI.
- Download format (PNG or JPEG).