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Luma Key: Key Out Brighter and Darker cut hard at Threshold, as After Effects

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After Effects' Luma Key removes everything darker (or brighter) than Threshold
and ignores Tolerance for those two key types; Tolerance only sets the band of
Key Out Similar / Dissimilar. EffectCraft ramped the matte over Tolerance, so
case 719 (a 50 % grey, Key Out Darker, Threshold 140, Tolerance 20) kept about
80 % of the layer where AE keys it out completely.

Measured in AE 2026 on a vertical grey ramp (cases 812-814): Darker keys up to
level 139.9 and keeps 140.1 (EffectCraft now the same row); Similar keys levels
120.3-160.0; with Edge Thin 1 / Edge Feather 2.5 the matte rises over rows
591-596 (EffectCraft within 0.2 of AE's alpha there). CPU and GPU.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
vangel76
2026-10-19 16:15:02 +02:00
co-authored by Claude Opus 5.5
parent dc9f15ada1
commit 39bd0efac2
3 changed files with 65 additions and 49 deletions
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crates/gpu/src/shaders/fx_key.wgsl
+4 -14
View File
@@ -199,23 +199,13 @@ fn fxk_point(@builtin(global_invocation_id) gid: vec3<u32>) {
let thr = f0.x;
let tol = f0.y;
var m: f32;
// As effects::keying::luma_key: Brighter / Darker cut hard at the threshold
// (Tolerance only shapes Similar / Dissimilar), as After Effects.
switch u0.y {
case 0u: {
if (tol > 0.0) {
m = clamp((thr + tol - l) / tol, 0.0, 1.0);
} else {
m = select(1.0, 0.0, l > thr);
}
}
case 0u: { m = select(1.0, 0.0, l > thr); }
case 2u: { m = select(1.0, 0.0, abs(l - thr) <= tol); }
case 3u: { m = select(0.0, 1.0, abs(l - thr) <= tol); }
default: {
if (tol > 0.0) {
m = clamp((l - (thr - tol)) / tol, 0.0, 1.0);
} else {
m = select(1.0, 0.0, l < thr);
}
}
default: { m = select(1.0, 0.0, l < thr); }
}
o = vec4<f32>(m);
}