JSPM

image-q

Complete Image Quantization Library in TypeScript (MIT License)

Table of Contents

• API Documentation
• Introduction
• Features
• Usage
• Todo
• Breaking changes
• Changelog
• Credits
• References
• License

Introduction

Image Color Number Reduction with alpha support using RGBQuant/NeuQuant/Xiaolin Wu's algorithms and Euclidean/Manhattan/CIEDE2000 color distance formulas in TypeScript Features

1. Platforms supported

   • Browser (Chrome 7.0+, FireFox 4.0+, IE 10+, Opera 11.6+, Safari 5.1+)
   • Node.js 6.0+

2. API

   • Basic API: sync and promise-based async
   • Advanced API: sync and generator-based

3. Builds

   • dist/cjs/image-q.js - CommonJS
   • dist/esm/image-q.js - ESM (ESNext)
   • dist/cjs/image-q.js - UMD

4. Import

   • HTMLImageElement
   • HTMLCanvasElement
   • NodeCanvas
   • ImageData
   • Array
   • CanvasPixelArray
   • Uint8Array
   • Uint32Array

5. Color Distance

   • Euclidean - 1/1/1/1 coefficients (originally used in Xiaolin Wu's Quantizer WuQuant)
   • EuclideanBT709NoAlpha - BT.709 sRGB coefficients (originally used in RGBQuant)
   • EuclideanBT709 BT.709 sRGB coefficients + alpha support
   • Manhattan - 1/1/1/1 coefficients (originally used in NeuQuant)
   • ManhattanBT709 - BT.709 sRGB coefficients
   • ManhattanNommyde - see https://github.com/igor-bezkrovny/image-quantization/issues/4#issuecomment-234527620
   • CIEDE2000 - CIEDE2000 (very slow)
   • CIE94Textiles - CIE94 implementation for textiles
   • CIE94GraphicArts - CIE94 implementation for graphic arts
   • CMetric - see http://www.compuphase.com/cmetric.htm
   • PNGQuant - used in pngQuant tool

6. Palette Quantizers

   • NeuQuant (original code ported, integer calculations)
   • NeuQuantFloat (floating-point calculations)
   • RGBQuant
   • WuQuant

7. Image Quantizers

   • NearestColor
   • ErrorDiffusionArray - two modes of error propagation are supported: xnview and gimp
     1. FloydSteinberg
     2. FalseFloydSteinberg
     3. Stucki
     4. Atkinson
     5. Jarvis
     6. Burkes
     7. Sierra
     8. TwoSierra
     9. SierraLite
   • ErrorDiffusionRiemersma - Hilbert space-filling curve is used

8. Output

   • Uint32Array
   • Uint8Array

Include image-q library into your project

ES6 module

// will import ESM (ESNext) or UMD version depending on your bundler/node
import * as iq from "image-q"

CommonJS

var iq = require("image-q");

As a global variable (Browser)

<script src="<path-to image-q/dist/umd/image-q.js>" type="text/javascript" charset="utf-8"></script>

Usage

Load Image (simple example)

var img = document.createElement("img");
img.onload = function() {
    // image is loaded, here should be all code utilizing image
    ...
}
img.src = "http://pixabay.com/static/uploads/photo/2012/04/11/11/32/letter-a-27580_640.png"

Generate Palette

// desired colors number
var targetColors = 256;
   
// create pointContainer and fill it with image
var pointContainer = iq.utils.PointContainer.fromHTMLImageElement(img);

// create chosen distance calculator (see classes inherited from `iq.distance.AbstractDistanceCalculator`)
var distanceCalculator = new iq.distance.Euclidean();

// create chosen palette quantizer (see classes implementing `iq.palette.AbstractPaletteQuantizer`) 
var paletteQuantizer = new iq.palette.RGBQuant(distanceCalculator, targetColors);
        
// feed out pointContainer filled with image to paletteQuantizer
paletteQuantizer.sample(pointContainer);

... (you may sample more than one image to create mutual palette) 

// take generated palette
var palette = paletteQuantizer.quantize();

Apply Palette to Image (Image Dithering)

// create image quantizer (see classes implementing `iq.image.AbstractImageQuantizer`)
var imageQuantizer = new iq.image.NearestColor(distanceCalculator);

// apply palette to image
var resultPointContainer = imageQuantizer.quantize(pointContainer, palette);

You may work with resultPointContainer directly or you may convert it to Uint8Array/Uint32Array

var uint8array = resultPointContainer.toUint8Array();

please read tests as reference of progress tracking feature

Breaking changes

2.1.1

+ PaletteQuantizer#quantize => PaletteQuantizer#quantizeSync
    + ImageQuantizer#quantize => ImageQuantizer#quantizeSync

2.0.1 - 2.0.4 (2018-02-22)

+ EuclideanRgbQuantWOAlpha => EuclideanBT709NoAlpha
+ EuclideanRgbQuantWithAlpha => EuclideanBT709
    + ManhattanSRGB => ManhattanBT709
    + IImageDitherer => AbstractImageQuantizer
    + IPaletteQuantizer => AbstractPaletteQuantizer
    + PointContainer.fromNodeCanvas => PointContainer.fromHTMLCanvasElement
    + PointContainer.fromArray => PointContainer.fromUint8Array
+ PointContainer.fromBuffer (Node.js, new)
    + CMETRIC => CMetric
    + PNGQUANT => PNGQuant
    + SSIM Class => ssim function

TODO

1. notification about progress
2. riemersma dithering
3. ordered dithering <-- is there anyone who needs it?
4. readme update, more examples
5. demo update (latest image-q npm version should be used in demo)

Changelog

2.1.1

+ Basic (Simple) API implemented
    + see breaking changes

2.0.5 (2018-02-23)

+ @types/node moved to 'dependencies'

2.0.4 (2018-02-23)

+ documentation added
    + some refactorings/renames, see breaking changes

2.0.3 (2018-02-22)

    + circular dependency removed

2.0.2 (2018-02-22)

+ readme updated

2.0.1 (2018-02-22)

+ progress tracking api (using es6 generators) added
    + strinct lint rules (+code cleanup/renames)
    + rollup (3 different versions - umd, cjs, esm + source maps + d.ts)
    + latest TypeScript
    + jest
    + snapshot tests
    + coverage (+coveralls)
    + greenkeeper

1.1.1 (2016-08-28)

+ CIEDE2000 - incorrect calculation fixed
+ CIEDE2000 - alpha channel now has only 25% impact on color distance instead of 66%
+ CIE94 - added 2 types (textiles and graphics art) according to spec
+ CIE94 - alpha support added
+ rgb2xyz, lab2xyz, xyz2rgb, xyz2lab - gamma correction
+ lab2xyz, xyz2lab - refY should be 100 (1.00000) instead of 10 (0.10000) 
+ manhattan with new (Nommyde) coefficients added 
+ mocha tests added
+ webpack integration
+ image-q is now UMD module 
+ travis-ci integration
+ typescript 2.0
+ indentation with 4 spaces

0.1.4 (2015-06-24)

+ Refactoring 
+ Riemersma dithering added (Hilbert Curve)
+ Readme.md updated
+ build.cmd updated

0.1.3 (2015-06-16)

+ NeuQuant is fixed (again) according to original Anthony Dekker source code (all values should be integer)
+ Error Diffusion Dithering is now calculates error like XNVIEW
+ Refactoring

0.1.2 (2015-06-16)

+ Documentation generation fixed
+ File name case problem fixed

0.1.1 (2015-06-16)

+ Auto-generated documentation added
+ Refactoring 

0.1.0 (2015-06-16)

+ Code cleanup, removed unnecessary files

0.0.5 (2015-06-16)

+ PNGQuant color distance added, need to check its quality
+ CIEDE2000 and CIE94 fixed for use in NeuQuant
+ NeuQuant is fixed according to original Anthony Dekker source code (all values should be integer) 
+ Code refactoring and cleanup
* We have some slowdown because of red/green/blue/alpha normalization according to white point per each calculateRaw/calculateNormalized call 

0.0.4 (2015-06-15)

+ CIEDE2000 color distance equation optimized (original CIEDE2000 equation is available as class `CIEDE2000_Original`) 

0.0.3b (2015-06-11)

+ CMetric color distance fixed

0.0.3a (2015-06-11)

+ Cleanup
+ Draft of CMetric color distance added

0.0.2 (2015-06-10)

+ rgb2xyz & xyz2lab fixed. CIEDE2000 works much better now.
+ CIE94 distance formula added. More investigation is needed.

0.0.1

+ Initial

Credits

Thanks to Leon Sorokin for information share and his original RGBQuant!

References

• Palette Quantization Algorithms

  1. RGBQuant (Leon Sorokin) JavaScript
  2. NeuQuant (Johan Nordberg) TypeScript
  3. NeuQuant (Tim Oxley) JavaScript
  4. NeuQuant (Devon Govett) JavaScript
  5. NeuQuant32 (Stuart Coyle) C
  6. Xiaolin Wu (Xiaolin Wu) C
  7. Xiaolin Wu (Smart-K8) C#
  8. Xiaolin Wu w/ Alpha (Matt Wrock) How to add Alpha, Source Code C#
  9. MedianCut (mwcz) GPLv3

• Image Quantization Algorithms

  1. All (ImageMagik doc)
  2. Error Diffusion dithering (Tanner Helland)
  3. Riemersma dithering TODO: Check License
  4. Ordered dithering (Joel Yliluoma)

• Color Distance Formulas

  Calculator + Info

  1. Euclidean Distance
  2. Manhattan Distance
  3. CIE94 Distance
     • Source Code (Iulius Curt)
  4. CIEDE2000
     • Math and Test Data Table (PDF)
     • Info
     • Source Code (Greg Fiumara) C
     • Source Code (THEjoezack) C#
     • Online Calculator
  5. Euclidean Distance w/o Alpha (RGBQuant)
  6. Euclidean Distance w/o sRGB coefficients (Xiaolin Wu Quant)
  7. Manhattan Distance w/o sRGB coefficients (NeuQuant)
  8. CMetric DRAFT!

• Color conversion formulas

  1. Pseudo-code

Be sure to fix rgb2xyz/xyz2lab. Issue is with strange part of code: r = r > 0.04045 ? .... Check http://en.wikipedia.org/wiki/Lab_color_space

• Image Quality Assessment

  1. SSIM info
  2. SSIM (Rhys-e) Java License: MIT
  3. PSNR ? TBD
  4. MSE ? TBD

• Other

  1. HUSL (Boronine) - info
  2. HUSL (Boronine) - code
  3. Color Image Quantization for Frame Buffer Display
  4. K-Means
  5. Efficient Color Quantization by Hierarchical Clustering Algorithms
  6. http://www.codeproject.com/Articles/66341/A-Simple-Yet-Quite-Powerful-Palette-Quantizer-in-C

License

MIT