mirror of
https://github.com/wiltodelta/remove-ai-watermarks.git
synced 2026-06-05 02:28:00 +02:00
Victor Kuznetsov
32a0779e1d
detect_watermark's shape-only NCC (spatial/gradient/var fusion) fires on ornate or flat content (text strips, banners, hatching) that coincidentally matches the diamond shape. The NCC is contrast-invariant, so it cannot see the defining property of a real Gemini sparkle: a bright WHITE overlay whose core sits above the local background. The fusion now demotes (caps confidence to 0.30) a match that is BOTH low-confidence (< _SPARKLE_FP_CONF 0.65) AND has a low core-ring brightness margin (_core_ring_margin < _SPARKLE_FP_MARGIN 5). Real sparkles escape via EITHER high confidence (white-bg sparkles score >=0.79 despite a low margin) OR high margin (dark/mid backgrounds, incl. the #36 faint-corner case), so both must fail to demote. The gate is monotonic -- it only removes detections, never adds -- so it cannot regress the verified-negative corpus (already 0 FPs). On the spaces corpus it demoted 16/495 flagged sparkles (13 no AI metadata = content FPs; the 3 AI-meta ones were visually FPs / a near-invisible white-on-white sparkle whose AI verdict is held by metadata), and dropped the removal-audit failures 20 -> 15. - _core_and_bg shared helper (core 75th-pct brightness vs background-ring median); _estimate_alpha_gain refactored onto it, new _core_ring_margin wrapper. - TestSparkleFalsePositiveGate: margin high/low, strong-sparkle kept (incl. on white via high conf), blurred no-core blob demoted. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>