Tune dithering palette RGB values for actual panel colors #2

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antialias · 2026-03-26T22:24:29Z

antialias commented

2026-03-26 22:24:29 +00:00

The Floyd-Steinberg dithering in dither.h uses approximate RGB values for the Spectra 6 palette. These need to be tuned against what the actual panel produces.

Current values:

Black: (0, 0, 0)
White: (255, 255, 255)
Red: (200, 30, 30)
Green: (0, 145, 0)
Blue: (0, 0, 160)
Yellow: (230, 210, 0)

Process:

Display solid color test patterns on the panel
Photograph under controlled lighting
Color-pick actual RGB values from the photos
Update PALETTE[] in dither.h
Compare before/after with a photo that has all 6 colors

Depends on #1 (hardware validation).

The Floyd-Steinberg dithering in `dither.h` uses approximate RGB values for the Spectra 6 palette. These need to be tuned against what the actual panel produces. **Current values:** - Black: (0, 0, 0) - White: (255, 255, 255) - Red: (200, 30, 30) - Green: (0, 145, 0) - Blue: (0, 0, 160) - Yellow: (230, 210, 0) **Process:** 1. Display solid color test patterns on the panel 2. Photograph under controlled lighting 3. Color-pick actual RGB values from the photos 4. Update `PALETTE[]` in `dither.h` 5. Compare before/after with a photo that has all 6 colors Depends on #1 (hardware validation).

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Reference: antialias/eink-photo-frame#2