vangel76andClaude Opus 5.5 b9182972b2 HDR Highlight Compression: match After Effects' measured transfer curve (#3123) ...

The effect used a soft knee on the brightest channel and left everything
below the knee unchanged. After Effects compresses the whole range. Fitting
our own 16-bit renders of an HDR ramp and coloured patches (Amount 0, 84,
90, 100) gives:

  Y    = max(0.30 R + 0.59 G + 0.11 B, 0)
  comp = min(c / (1 + Y), 1)                    per channel
  out  = ((1 - t) c^0.4 + t comp^0.4)^(1/0.4)   t = Amount / 100

A grey value x maps to x / (1 + x) at Amount 100. The worst error against AE
drops from 985 to about 2-4 of 65535 at Amounts 100, 90 and 84. Amount 0
stays identical.

CPU and GPU change together. Tests: a reference table of measured values,
GPU parity at Amount 90, and over-range input that exercises the clip at 1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-11-05 17:02:26 +01:00

..

src

HDR Highlight Compression: match After Effects' measured transfer curve (#3123)

2026-11-05 17:02:26 +01:00

Cargo.toml

GPU.1: Preserve CPU parity in numerical effect kernels (#1490)

2026-11-03 23:19:29 +01:00