Replace the default text-protection path. Differential Diffusion froze text in
latent space, which left SynthID intact inside text (violating remove-everywhere)
and still softened sub-8px strokes (VAE latent limit). _run_region_hires instead
scrubs the whole image, then re-scrubs each detected text block at high resolution
and feather-composites it back: every pixel is regenerated (watermark removed
everywhere) while small text stays crisp (high-res strokes span >1 latent cell).
merge_text_regions + feather_paste are pure and unit-tested; each re-scrubbed
patch is phase-correlated back to the original crop to null the ~1-2px round-trip
offset. Synthetic 18px multilingual text: text-region SSIM 0.28 -> 0.48, visually
garbled -> readable across Latin/Cyrillic/CJK. Legacy _run_differential /
build_change_map remain but are no longer the default. Prod use still requires
confirming via the SynthID oracle that re-scrubbed text zones read watermark-free.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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>
SDXL img2img regenerates every pixel, so small text and CJK glyphs deform
at the strengths that defeat SynthID (issue #21). With --protect-text a
CJK-native PP-OCRv3 detector (2.4 MB ONNX, cv2.dnn, no torch, cached on
first use) locates text regions and the pass switches to the SDXL
Differential-Diffusion community pipeline: a per-pixel change map keeps
text regions largely intact while the background is regenerated to strip
the watermark. Gated to the SDXL default model; falls back to plain
img2img with a warning when unavailable.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Victor Kuznetsov