Original PickImageColors source-file lab, 2026-10-25.
Why can a PNG export change colors before picking?
Run: python reproduce.py --case png-quantization-color-changes --out rerun
Dependency: Pillow. Recorded runtime: Python 3.12.14, Pillow 12.3.0, libwebp 1.6.0.
Measurements are local source-file computations, not browser observations. Library-dependent compression sizes and quantizer choices may change with runtime.
The four output representatives are measurements from this MEDIANCUT run. Other quantizers, dithering settings and library versions may choose different representatives. We did not measure a browser’s automatic palette or promise that every PNG export uses this reduction.
