iWantHue

Colors for data scientists. Generate and refine palettes of optimally distinct colors.

iWantHue allows you to generate palettes of colors. It is about mastering the properties of a palette by setting a range of Hue, Chroma (unbiased saturation) and Lightness. You can generate palettes of any size or just get the generator for a javascript project. The algorithm optimizes the perceptive distance in the color subspace, ensuring an optimal readability.

How it works

1. K-means or force vector repulsion algorithms ensure an even distribution of colors
2. The CIE Lab color space is used for computation, since it fits human perception
3. The Hue/Chroma/Lightness color space is used to set constraints, since it is user-friendly

Examples and a tutorial

Idea

The idea behind iWantHue is to distribute colors evenly, in a perceptively coherent space, constrained by user-friendly settings, to generate high quality custom palettes.

Explanations and an experiment on color theory

How to use it in your own code

You can install iwanthue for node.js and the browser using npm:

npm install iwanthue

Usage

var iwanthue = require('iwanthue');

// Generate a simple palette with 5 colors
var palette = iwanthue(5);

// With some options
var palette = iwanthue(5, {
  clustering: 'force-vector',
  seed: 'cool-palette',
  quality: 100
});

Arguments

• count number: number of colors in the generated palette.
• settings ?object: Settings:
  • attempts ?number [1]: Number of times should the function try to generate a palette in order to only keep the one maximizing the minimum distance between two of the palette colors. Will only make a single attempt by default.
  • colorSpace ?string|object|array [default]: Color space preset. Check this file for the full list of preset names, or go to the website to try them. Alternatively you can pass the colorSpace either as a [hmin, hmax, cmin, cmax, lmin, lmax] array or a {hmin, hmax, cmin, cmax, lmin, lmax} object where keys can be omitted.
  • colorFilter ?function: Function used to filter suitable colors. Takes a [r, g, b] color and the same [l, a, b] color as arguments.
  • clustering ?string [k-means]: Clustering method to use. Can either be k-means or force-vector.
  • quality ?number [50]: Quality of the clustering: iterations factor for force-vector, colorspace sampling for k-means.
  • ultraPrecision ?boolean [false]: Ultra precision for k-means colorspace sampling?
  • distance ?string [euclidean]: Distance function to use. Can be euclidean, cmc, compromise (colorblind), protanope, deuteranope or tritanope.
  • seed ?string|number: Random number generator seed. Useful to produce the same palette every time based on some data attribute.

Palette

A helper class representing a categorical color palette over a set of given values.

// To build your palette from a unique list of values
var Palette = require('iwanthue/palette');

var palette = Palette.generateFromValues(
  'cities',
  ['one', 'two', 'three'],
  {defaultColor: '#000'}
);

palette.get('one');
>>> '#19d3a2'

palette.get('unknown');
>>> '#000'

// From entries
var palette = Palette.fromEntries(
  'cities',
  [['one', 'red'], ['two', 'blue']],
  '#000'
);

// From mapping
var palette = Palette.fromMapping(
  'cities',
  {one: 'red', two: 'blue'},
  'red'
);

Palette.generateFromValues arguments

• name string: palette or category name used as seed for iwanthue.
• values iter: unique values for the represented category.
• settings ?object:
  • defaultColor ?string [#ccc]: default color to return in case desired value is not known.
  • ... any setting that can be passed to iwanthue.

Palette.fromEntries arguments

• name string: palette or category name used as seed for iwanthue.
• entries iter: key, value entries mapping values to colors.
• defaultColor ?string [#ccc]: default color to return in case desired value is not known.

Palette.fromMapping arguments

• name string: palette or category name used as seed for iwanthue.
• mapping object|Map: mapping from values to colors.
• defaultColor ?string [#ccc]: default color to return in case desired value is not known.

Palette.fromJSON arguments

• data object: serialized palette data ({name, defaultColor, entries}).

Palette members

• name string: name of the palette.
• size number: number of colors.
• defaultColor string: default color.
• map Map: map from values to colors.

Palette methods

• get: return the color for the given value or the default color if value is unkown.
• has: return whether the value is known to the palette.
• forEach: callback iteration over (color, value).
• colors: return the palette's colors as an array.
• toJSON: return the palette in a serialized format fit for JSON.

Precomputed palettes

If you don't want to load iwanthue's whole code into your client app or if you just want to prototype things quickly, the npm module also packs some precomputed palettes that you can import.

All of the presets export palettes ranging from 2 to 15 colors.

Here is how to load them:

// Default palettes
var palettes = require('iwanthue/precomputed');

// Need a palette for 6 colors:
var sixColorsPalette = palettes[6];

// K-means palettes
var palettes = require('iwanthue/precomputed/k-means');

// Force vector palettes
var palettes = require('iwanthue/precomputed/force-vector');

// Colorblind alternatives
var palettes = require('iwanthue/precomputed/k-means-colorblind');
var palettes = require('iwanthue/precomputed/force-vector-colorblind');

Here is the full list of precomputed palettes:

iwanthue/precomputed/force-vector
iwanthue/precomputed/index
iwanthue/precomputed/k-means
iwanthue/precomputed/ultra-k-means
iwanthue/precomputed/force-vector-colorblind
iwanthue/precomputed/k-means-colorblind
iwanthue/precomputed/k-means-all
iwanthue/precomputed/force-vector-all
iwanthue/precomputed/k-means-fancy-light
iwanthue/precomputed/force-vector-fancy-light
iwanthue/precomputed/k-means-fancy-dark
iwanthue/precomputed/force-vector-fancy-dark
iwanthue/precomputed/k-means-shades
iwanthue/precomputed/force-vector-shades
iwanthue/precomputed/k-means-tarnish
iwanthue/precomputed/force-vector-tarnish
iwanthue/precomputed/k-means-pastel
iwanthue/precomputed/force-vector-pastel
iwanthue/precomputed/k-means-pimp
iwanthue/precomputed/force-vector-pimp
iwanthue/precomputed/k-means-intense
iwanthue/precomputed/force-vector-intense
iwanthue/precomputed/k-means-fluo
iwanthue/precomputed/force-vector-fluo
iwanthue/precomputed/k-means-red-roses
iwanthue/precomputed/force-vector-red-roses
iwanthue/precomputed/k-means-ochre-sand
iwanthue/precomputed/force-vector-ochre-sand
iwanthue/precomputed/k-means-yellow-lime
iwanthue/precomputed/force-vector-yellow-lime
iwanthue/precomputed/k-means-green-mint
iwanthue/precomputed/force-vector-green-mint
iwanthue/precomputed/k-means-ice-cube
iwanthue/precomputed/force-vector-ice-cube
iwanthue/precomputed/k-means-blue-ocean
iwanthue/precomputed/force-vector-blue-ocean
iwanthue/precomputed/k-means-indigo-night
iwanthue/precomputed/force-vector-indigo-night
iwanthue/precomputed/k-means-purple-wine
iwanthue/precomputed/force-vector-purple-wine

More info

• The tool itself is available online
• Its source code is available on GitHub
• If you have issues or requests, tell us about them
• You will find more tools on Médialab Tools