Claude ecb2cf1d32 Blend modes: classic modes fade with opacity and HDR modes keep over-range values, as in After Effects (#494) ...

Measured against After Effects at 32 bpc:

- Classic Color Dodge, Classic Color Burn and Classic Difference at partial opacity: AE
  fades the source toward the mode's neutral colour (0 for Dodge and Difference, 1 for
  Burn) by the opacity and applies the classic formula at full strength (b / (1 − k·o),
  |b − k·o|, 1 − (1 − b) / (1 − k·(1 − o))). We mixed the full-strength result by opacity:
  up to 45/255 off on ordinary 0–1 footage.
- Overlay, Exclusion, Luminosity, Color Burn and Classic Color Burn keep their plain formula
  for values above 1 (HDR passes). They were missing from `supports_hdr`, so their inputs
  were clamped to 0–1 (Exclusion was up to 208/255 off); Classic Color Burn also clamped
  its result at 0, where AE keeps negative values.

The CPU blend (color::blend_pixel) and the GPU kernel (common.wgsl) change together.

Tests: the reporter's formulas for each case (blend.rs); the CPU/GPU parity test of every
blend mode at every bit depth (over-range values, 70 % opacity) passes.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01QiAJeFttZp83Fh7YuzAR5f

2026-10-10 20:51:24 +00:00

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src

Blend modes: classic modes fade with opacity and HDR modes keep over-range values, as in After Effects (#494)

2026-10-10 20:51:24 +00:00

Cargo.toml

M0.1–M0.7: workspace, time/geom/color/keyframe/project/raster/path/text/effects/render crates

2026-10-01 14:05:20 -04:00