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BGfilter/configs/default.yaml
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lhk229 9b7a192599 Use pymatting ML foreground estimation to remove edge spill
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>
2026-06-30 17:33:35 +08:00

37 lines
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YAML

model:
model_name: hustvl/vitmatte-base-composition-1k
device: cuda
matting_method: vitmatte
fallback_to_chroma_alpha: false
trimap:
sure_bg_threshold: 0.92
sure_fg_threshold: 0.12
unknown_radius_ratio: 0.012
fg_safe_radius_ratio: 0.006
foreground:
enabled: true
method: ml
fallback_to_unmix: true
ml_regularization: 0.00001
# Legacy "unmix" method params (used only when method: unmix).
edge_low: 0.005
edge_high: 0.995
min_unmix_alpha: 0.08
unmix_strength: 0.70
local_strength: 0.45
local_blur_radius: 11
local_alpha_threshold: 0.92
local_bg_confidence_max: 0.20
green_excess_margin: 0.015
bg_confidence_weight: 0.70
despill:
enabled: true
edge_low: 0.005
strength: 0.92
green_excess_margin: 0.015
edge_expand_radius: 2
alpha_weight_floor: 0.35