Add bgfilter/recolor.py: after despill, propagate clean neighbour chroma into
pixels whose colour is still off (residual green, or the magenta a green unmix
overshoots into), keeping luminance partway so hair texture survives. It installs
a real observed colour rather than subtracting, so it cannot overshoot. Despill
already neutralises the matte edge (off ~ 0 there), so recolor only touches the
contaminated interior and the wisps the dropout-fill rescued.
Runs as a final colour pass on the despilled foreground; pymatting + despill keep
their stronger edge handling. On the samples the magenta fringe drops sharply
(TestImage vis-magenta 0.065->0.014, TestImage2 0.085->0.031) with edge green
unchanged (vis-green ~0.02). Debug output color_mask.png replaces the despill /
foreground-background / foreground-correction maps; smoke updated.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
After the full-foreground despill (5ddf0cd) the residual green was confined to
semi-transparent hair (alpha < 0.5): 85% of the worst pixels had alpha < 0.3,
where a pixel-wise unmix (divide by small alpha) is too noisy to trust.
Replace the hand-rolled unmix/local-blur estimator with pymatting's
estimate_foreground_ml (Germer et al. multi-level closed form), which propagates
reliable foreground colour from high-alpha neighbours into the fringe and
estimates the background, so green spill is unmixed rather than clamped. The
despill pass stays as a light cleanup on top.
- foreground.method selects "ml" (default) or "unmix" (legacy heuristic kept as
a fallback when pymatting is unavailable, matching the chroma fallback idiom).
- ForegroundEstimate now exposes rgb (F), background (B) and a correction map;
debug outputs become foreground_rgb / foreground_background / foreground_correction.
Controlled comparison (same ViTMatte alpha, only foreground method changed),
edge_green_excess:
TestImage p95 0.176->0.031, mean 0.061->0.005
TestImage2 p95 0.165->0.004, mean 0.052->0.002
Adds pymatting (pulls in numba) to requirements.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
lhk229
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