color-mage

Color mage

A dependency-free image color extraction library.

The extraction consists of using K-Means algorithm.

It has a few utility functions as well!

NOTE: This library compiles to Ecmascript modules target.

Example

This picture was downloaded from Unsplash - link

Functions

• Color extractors
• • kMeansColorExtractor: Function that extracts colors from a given array of pixels using K-Means algorithm.
• Converters
• • convertImageDataToRgba: Function that converts raw imageData.data array into an array of RGBA objects.
• • convertRgbToHex: Converts an RGB color into it hexadecimal representation.
• Counters
• • rgbaCounter: Counts unique colors from the given array of RGBA colors, you can determine if you want it to consider the alpha channel or not.

Install

With npm:

npm i color-mage
# or
yarn add color-mage

Usage

import { convertImageDataToRgba, kMeansColorExtractor, convertRgbToHex } from 'color-mage'

const canvas = document.getElementById('#canvas') as HTMLCanvasElement
const ctx = canvas.getContext('2d')
// draw your image
ctx.drawImage(image, 0, 0, 640, 480)
// then get the image data from canvas
const imageData = ctx.getImageData(0, 0, 640, 480)

// converts the imageData array into an array of colors
const colors = convertImageDataToRgba(imageData.data)

// RGBA color representation
const palette = kMeansColorExtractor(colors, 5)

// All colors converted into hexadecimal representation
const hexColors = palette.map(convertRgbToHex)

Tips

The process might take longer depending on the output size of ctx.getImageData, since it will result in more pixels to process.

It might take longer as well if the image has many colors or the maxRuns in kMeansColorExtractor parameter is higher.

As you can see in the example below, the maxRuns is a tradeoff between color accuracy and time to process.

An example using a 8K image:

• Extracting 10 colors and maxRuns equals to 50

• imageData extracted with size of 800x450px using ctx.getImageData(0, 0, 800, 450)

• Metrics:

• • Get drawn canvas (draw image in canvas element): 14 ms
• • Get image data (gets the image data from drawn canvas): 98 ms
• • Convert imageData to RGBA (convertImageDataToRgba): 30 ms
• • Extract colors (kMeansColorExtractor): 845 ms
• • Total: 988 ms

• The same image and output size, but with maxRuns equals to 10 (default)

• Metrics:

• • Get drawn canvas: 18 ms
• • Get image data: 89 ms
• • Convert imageData to RGBA: 32 ms
• • Extract colors: 326 ms
• • Total: 466 ms

License

MIT