@4bitlabs/color

A collection color manipulation functions and predefined palettes for working with EGA/CGA images.

Documentation

Full documentation for the library can be found here.

Palettes

Predefined Palettes

Palette
Palettes.CGA_PALETTE	IBM's CGA Palette
Palettes.TRUE_CGA_PALETTE	VileR's "True" CGA Palettte
Palette.DGA_PALETTE	Adigun A. Polack's AAP-DGA16
Palette.COLLY_SOFT_PALETTE	collyflower05's SOFT CGA PALETTE

Using your own Palette

const customPalette = Uint32Array.of(
  //AA-BB-GG-RR
  0xff_1f_1f_1f, // color 0
  /*        ...           */
  /* snip 14 more entries */
  /*        ...           */
  0xff_e0_e0_e0, // color 15
);

Predefined Dither Pairs

Mix	Palette	Mix
Dithers.CGA	CGA	none
Dithers.CGA_MIX	CGA	25% mix
Dithers.CGA_FLAT	CGA	50% mix (SCUMMVM de-dithering)
Dithers.CGA_SOFT	CGA	Dynamic mix
Dithers.TRUE_CGA	TRUE-CGA	none
Dithers.TRUE_CGA_MIX	TRUE-CGA	25% mix
Dithers.TRUE_CGA_FLAT	TRUE-CGA	50% mix (SCUMMVM de-dithering)
Dithers.TRUE_CGA_SOFT	TRUE-CGA	Dynamic mix

Generating your own Dither Pairs

import { Dithers, Mixers } from '@4bitlabs/color';

const pairs = Dithers.generatePairs(customPalette, Mixers.softMixer());

IBM 5153 Contrast Knob

import { IBM5153Contrast } from '@4bitlabs/color';

// Simulate turning the constrast knob on a IBM-5153 to about 50%
const palette = IBM5153Contrast(Palettes.CGA_PALETTE, 0.5);

Simulating Grayscale

const grays = toGrayscale(Palettes.CGA_PALETTE);