Image Quantization Library (image-q)

IQ.ts

Image Quantization Library in TypeScript (MIT 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

API
Online Demo
Demo Source

Capability

title	description
Import	HTMLImageElement, HTMLCanvasElement, NodeCanvas, ImageData, Array, CanvasPixelArray, Uint8Array, Uint32Array
Palette	NeuQuant, RgbQuant, Xiaolin Wu's method
Image	Nearest Color, Error Diffusion Dithering
Export	Uint32Array, Uint8Array

Include IQ Library into your project

TypeScript + Node.js/Browser project

/// <reference path='<path-to-iq>/src/iq.ts' />

JavaScript + Node.js project

var iq = require("<path-to-iq>/dist/node-iq.js");

JavaScript + Browser project

<script src="<path-to-iq>/dist/browser-iq.js" type="text/javascript" charset="utf-8"></script>

Usage Example

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 implementing `IQ.Distance.IDistanceCalculator`)
var distanceCalculator = new IQ.Distance.Euclidean();

// create chosen palette quantizer (see classes implementing `IQ.Palette.IPaletteQuantizer`) 
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.IImageDitherer`)
var imageDitherer = 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();

TODO

1. notification about progress
~~2. riemersma dithering~~
3. ordered dithering

Changelog

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

License

License MIT (NeuQuant use also forces to add it's copyright notice into source code)

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

  1. Euclidean Distance
  2. Manhattan Distance
  3. CIE94 Distance
     • Source Code (Iulius Curt)
  4. CIEDE2000
     • Math and Test Data Table (PDF)
     • Source Code (Greg Fiumara) C
  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