FA-10552 / Raster compositing / Member archive
Unpremultiply transparent color · case 02
Premultiplied channels are exposed as straight channels and darken translucent pixels.
Case contract
Input is valid premultiplied normalized RGBA. Divide RGB by nonzero alpha; represent fully transparent output as transparent black.
Why this case matters
A deterministic software graphics stage with explicit channel and coordinate conventions; no hardware, device profile or API behavior is inferred.
One recorded failure
Sample boundary fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| fixture 1 | [0.5, 0.25, 0.125, 0.5] | [1, 0.5, 0.25, 0.5] | Failed |
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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.
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