color-diff

Implements the CIEDE2000 color difference algorithm, conversion between RGB and LAB color and mapping all colors in palette X to the closest color in palette Y based on the CIEDE2000 difference.

Installation

npm install color-diff --save

Tests

Are located in the test/ folder and are run by:

npm test

Usage

// CommonJS
const { 
  closest, 
  furthest,
  diff, 
  mapPalette,
  paletteMapKey,
  rgbaToLab,
  mapPaletteLab,
  labPaletteMapKey,
} = require("color-diff");

// ESM
import {
  closest,
  furthest,
  diff,
  mapPalette,
  paletteMapKey,
  rgbaToLab,
  mapPaletteLab,
  labPaletteMapKey,
} from "color-diff";

closest(color, palette, bc)

Returns the closest color. The parameter bc is optional and is used as background color when the color and/or palette uses alpha channels.

const color = { R: 255, G: 1, B: 30 };
// red, green, blue
const palette = [ {R: 255, G: 0, B: 0 },
                {R: 0, G: 255, B: 0 },
                {R: 0, G: 0, B: 255} ];

closest(color, palette); // {R: 255, G: 0, B: 0 }, red

The result above is obvious, but diff.closest could deal with more complicated cases.

furthest(color, palette, bc)

Returns the most different color. The parameter bc is optional and is used as background color when the color and/or palette uses alpha channels.

const color = { R: 255, G: 255, B: 255 };
// black, white
const palette = [ {R: 0, G: 0, B: 0 }, {R: 255, G: 255, B: 255 } ];

furthest(color, palette); // {R: 0, G: 0, B: 0 }, black

The result above is obvious, but diff.furthest could deal with more complicated cases.

mapPalette(palette1, palette2)

Returns a mapping from the colors in palette1 to palette2.

paletteMapKey(color)

Return the palette map key for the color, to be used with the result from mapPalette.

diff(color1, color2, bc)

Returns the difference between the lab colors color1 and color2. The parameter bc is optional and is used as background color when one of the colors uses alpha channels.

rgba color

Object

RGBAColor is an object containing 4 properties: 'R', 'G', 'B', 'A', where 'A' is optional OR 'r', 'g', 'b', 'a', where 'a' is optional . Such as:

{ R: 255, G: 1, B: 0 }

There is an optional property 'A', which specifies the alpha channel between 0.0 and 1.0. If not present the color will be treated as fully opaque, i.e. A = 1.0.

Each RGBA-color is transformed into a RGB-color before being used to calculate the CIEDE2000 difference, using the specified background color (defaults to white).

lab color

Object

LabColor is an object containing 3 properties 'L', 'a', 'b' such as:

{ L: 100, a: 0.005, b: -0.010 }

palette

Array.<RGBAColor>

Color palette array which contains many RGBAColor objects.

Author

Markus Ekholm

License

3-clause BSD. For details see COPYING.