The veto's suspect zone was defined by background-hue projection, so
--no-chroma silently skipped it. Without a key colour there is no hue
test to lean on, so in complex mode the gate instead requires the second
opinion itself to be confidently near-empty (second_lo -> second_hi ramp,
default 0.15 -> 0.40): regions the HR-matting model decisively rejects
can be cleared, while thin strands it merely blurs to mid-alpha are
untouched -- protecting exactly the crisp-strand advantage the pipeline
has over a raw BiRefNet mask. Flat mode's gate is unchanged.
Validation (BG_IMAGE01-04, cuda fp32): flat default path bit-identical;
complex-mode veto touches 0.007-0.025% of pixels, visibly clearing
blurred residue near strands and milky specks in hair gaps with no
strand erosion. Costs the HR-matting forward in --no-chroma runs
(0.61 -> 1.6 s/image warm GPU); disable with --no-cross-check.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
lhk229
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