watermarks-remover/skills/remove-ai-marks/references/markdiffusion.md

MarkDiffusion (THU-BPM) — reference

External research backend: THU-BPM/MarkDiffusion (JMLR; Apache-2.0). A generative watermarking toolkit for latent diffusion models — it embeds marks, it does not remove them. This repo uses it as a controlled-experiment harness and as an optional regeneration-removal engine.

What it covers (image-only scope)

Nine image algorithms in two categories:

Category	Algorithms	Notes
Pattern-based	Tree-Ring, Ring-ID, ROBIN, WIND, SFW	A fixed latent/FT pattern is injected at generation and inverted for detection
Key-based	Gaussian-Shading, GaussMarker, PRC, SEAL	A secret key modulates the noise/latent; detection needs the key

(Video algorithms VideoShield / VideoMark are out of scope for this project.)

What it gives the remover

• Same-scheme detector for the above algorithms via AutoWatermark.load(...).detect_watermark_in_media(). Covers the Tree-Ring-class gap in removal-matrix.md; it does not cover StegaStamp, StableSignature, or SynthID-media.
• DiffusionPurification — a blind regeneration attack (DiffPure-style: encode → partial noise → reverse-denoise) usable as a pixel-watermark remover. Exposed as --remove-pixel diffusion in clean_image.py.
• NeuralCodecCompression — codec round-trip (compressai). Not wired here.

Hard honesty constraints

1. Detection is same-scheme and same-model only. Inversion-based detection requires the generating model (and for key-based schemes the key). It proves "this image came from this model/config/params" — it cannot certify that a vendor detector will fail on an arbitrary image. This is the same same-config-only caveat as the MarkLLM text harness.
2. DiffusionPurification is blind regeneration. It reuses the same pipeline, so it will not defeat a watermark that is robust to its own regeneration path, and it drifts image content (more than CtrlRegen's controllable ControlNet regeneration). Conservative strength default (0.3), treated as a fallback/comparison engine, never a guarantee.
3. Heavy stack. torch ≥ 2.4,<2.11 + diffusers + a Stable Diffusion model download (~4–10 GB). GPU strongly recommended. Some HF models are gated → HF_TOKEN (env only, never argv).

License / hygiene

Apache-2.0. Installed from PyPI at a pinned version (requirements-markdiffusion.txt) or an editable checkout at a pinned commit (setup_markdiffusion.sh --checkout). Never bundled into this repo.

Harness usage

SCRIPTS=skills/remove-ai-marks/scripts
MD="$HOME/markdiffusion/.venv/bin/python"

"$SCRIPTS/setup_markdiffusion.sh"                     # PyPI pin default
# or: "$SCRIPTS/setup_markdiffusion.sh" --checkout    # editable pinned clone

# 1. watermark a test image with a scheme
echo "a red fox in snow" > /tmp/prompt.txt
"$MD" "$SCRIPTS/markdiffusion_harness.py" watermark /tmp/prompt.txt \
  -o /tmp/wm.png -o2 /tmp/plain.png --scheme tr --json

# 2. remove (blind regeneration)
"$MD" "$SCRIPTS/markdiffusion_harness.py" purify /tmp/wm.png \
  -o /tmp/wm.purified.png --purification-strength 0.3 --json

# 3. re-detect with the SAME scheme config
"$MD" "$SCRIPTS/markdiffusion_harness.py" detect /tmp/wm.purified.png \
  --scheme tr --detector-type l1_distance --json

Exit codes: 0 ok · 1 runtime error · 2 bad input · 3 backend unavailable.

References

• Paper: https://arxiv.org/abs/2509.10569
• Docs: https://markdiffusion.readthedocs.io
• HF models: https://huggingface.co/Generative-Watermark-Toolkits