<!DOCTYPE html>
<html>
<head>
<title>Extract Image Color: with and without worker</title>
<meta charset="utf-8">
<link rel="stylesheet" href="styles/style.css">
<script src="scripts/lib/color-thief.js"></script>
<script src="scripts/color-extractor.js"></script>
<script>
var colorThief = new ColorThief();
var colorExtractorWorker = new ColorExtractorWorker();
function createImageNodes(useWorker) {
var imgContainer = document.getElementById('images'),
imgWrapper,
img,
i,
count = 50;
for (i = 0; i < count; i++) {
imgWrapper = imgContainer.appendChild(document.createElement('div'));
imgWrapper.className = 'img-wrapper';
img = imgWrapper.appendChild(document.createElement('img'));
img.addEventListener('load', function() {
if (useWorker) {
calculateColorUsingWorker(this);
} else {
calculateColorDirectly(this);
}
});
img.crossOrigin = 'anonymous';
img.src = 'http://lorempixel.com/800/60' + ((i % 5) + 1) + '/';
}
}
function setBackgroundColor(element, color) {
var value = 'rgb(' + color[0] + ', ' + color[1] + ', ' + color[2] + ')';
element.style.backgroundColor = value;
}
function calculateColorDirectly(img) {
var dominantColor = colorThief.getColor(img);
setBackgroundColor(img.parentNode, dominantColor);
}
function calculateColorUsingWorker(img) {
colorExtractorWorker.processImage(img, function(dominantColor) {
setBackgroundColor(img.parentNode, dominantColor);
});
}
document.addEventListener("DOMContentLoaded", function() {
document.getElementById('btn-without-worker').addEventListener('click', function() {
createImageNodes(false);
});
document.getElementById('btn-with-worker').addEventListener('click', function() {
createImageNodes(true);
});
document.getElementById('btn-clear').addEventListener('click', function() {
var imgContainer = document.getElementById('images');
while (imgContainer.firstChild) {
imgContainer.removeChild(imgContainer.firstChild);
}
});
});
</script>
</head>
<body>
<div class="actions">
<button id="btn-without-worker">Add images without worker</button>
<button id="btn-with-worker">Add images with worker</button>
<button id="btn-clear">Clear</button>
</div>
<div id="images"></div>
</body>
</html>
body {
margin: 0;
padding: 0;
}
.actions {
text-align: center;
margin: 15px;
}
.img-wrapper {
height: 100px;
text-align: center;
}
.img-wrapper img {
height: 80px;
margin: 10px 0;
}
"use strict";
function ColorExtractorWorker() {
var self = this;
self.worker = new Worker('scripts/color-extractor-worker.js');
self.lastRequestId = 0;
self.callbacksById = {};
self.worker.addEventListener('message', function(e) {
var requestId = e.data.requestId,
dominantColor = e.data.dominantColor,
callback = self.callbacksById[requestId];
self.callbacksById[requestId] = undefined;
callback(dominantColor);
});
}
ColorExtractorWorker.prototype.processImage = function(img, callback) {
var imageData = this.getImageDataFromCanvas(img);
if (imageData) {
var requestId = ++this.lastRequestId;
this.callbacksById[requestId] = callback;
this.worker.postMessage({
requestId: requestId,
imageData: imageData
});
} else {
callback();
}
};
ColorExtractorWorker.prototype.getImageDataFromCanvas = function(img) {
var canvas = document.createElement('canvas'),
context = canvas.getContext('2d'),
width,
height,
data;
document.body.appendChild(canvas);
width = canvas.width = img.width;
height = canvas.height = img.height;
context.drawImage(img, 0, 0, width, height);
data = context.getImageData(0, 0, width, height);
canvas.parentNode.removeChild(canvas);
return data;
};
"use strict";
importScripts('lib/quantize.js');
addEventListener('message', function(e) {
var requestId = e.data.requestId,
imageData = e.data.imageData,
dominantColor = getColor(imageData);
postMessage({
requestId: requestId,
dominantColor: dominantColor
});
});
function getColor(imageData, quality) {
var palette = getPalette(imageData, 5, quality);
return palette[0];
}
function getPalette(imageData, colorCount, quality) {
if (typeof colorCount === 'undefined') {
colorCount = 10;
}
if (typeof quality === 'undefined') {
quality = 10;
}
// Create custom CanvasImage object
var pixels = imageData.data;
var pixelCount = pixels.length;
// Store the RGB values in an array format suitable for quantize function
var pixelArray = [];
for (var i = 0, offset, r, g, b, a; i < pixelCount; i = i + quality) {
offset = i * 4;
r = pixels[offset + 0];
g = pixels[offset + 1];
b = pixels[offset + 2];
a = pixels[offset + 3];
// If pixel is mostly opaque and not white
if (a >= 125) {
if (!(r > 250 && g > 250 && b > 250)) {
pixelArray.push([r, g, b]);
}
}
}
// Send array to quantize function which clusters values
// using median cut algorithm
var cmap = MMCQ.quantize(pixelArray, colorCount);
var palette = cmap.palette();
return palette;
}
/*!
* quantize.js Copyright 2008 Nick Rabinowitz.
* Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php
*/
// fill out a couple protovis dependencies
/*!
* Block below copied from Protovis: http://mbostock.github.com/protovis/
* Copyright 2010 Stanford Visualization Group
* Licensed under the BSD License: http://www.opensource.org/licenses/bsd-license.php
*/
if (!pv) {
var pv = {
map: function(array, f) {
var o = {};
return f
? array.map(function(d, i) { o.index = i; return f.call(o, d); })
: array.slice();
},
naturalOrder: function(a, b) {
return (a < b) ? -1 : ((a > b) ? 1 : 0);
},
sum: function(array, f) {
var o = {};
return array.reduce(f
? function(p, d, i) { o.index = i; return p + f.call(o, d); }
: function(p, d) { return p + d; }, 0);
},
max: function(array, f) {
return Math.max.apply(null, f ? pv.map(array, f) : array);
}
}
}
/**
* Basic Javascript port of the MMCQ (modified median cut quantization)
* algorithm from the Leptonica library (http://www.leptonica.com/).
* Returns a color map you can use to map original pixels to the reduced
* palette. Still a work in progress.
*
* @author Nick Rabinowitz
* @example
// array of pixels as [R,G,B] arrays
var myPixels = [[190,197,190], [202,204,200], [207,214,210], [211,214,211], [205,207,207]
// etc
];
var maxColors = 4;
var cmap = MMCQ.quantize(myPixels, maxColors);
var newPalette = cmap.palette();
var newPixels = myPixels.map(function(p) {
return cmap.map(p);
});
*/
var MMCQ = (function() {
// private constants
var sigbits = 5,
rshift = 8 - sigbits,
maxIterations = 1000,
fractByPopulations = 0.75;
// get reduced-space color index for a pixel
function getColorIndex(r, g, b) {
return (r << (2 * sigbits)) + (g << sigbits) + b;
}
// Simple priority queue
function PQueue(comparator) {
var contents = [],
sorted = false;
function sort() {
contents.sort(comparator);
sorted = true;
}
return {
push: function(o) {
contents.push(o);
sorted = false;
},
peek: function(index) {
if (!sorted) sort();
if (index===undefined) index = contents.length - 1;
return contents[index];
},
pop: function() {
if (!sorted) sort();
return contents.pop();
},
size: function() {
return contents.length;
},
map: function(f) {
return contents.map(f);
},
debug: function() {
if (!sorted) sort();
return contents;
}
};
}
// 3d color space box
function VBox(r1, r2, g1, g2, b1, b2, histo) {
var vbox = this;
vbox.r1 = r1;
vbox.r2 = r2;
vbox.g1 = g1;
vbox.g2 = g2;
vbox.b1 = b1;
vbox.b2 = b2;
vbox.histo = histo;
}
VBox.prototype = {
volume: function(force) {
var vbox = this;
if (!vbox._volume || force) {
vbox._volume = ((vbox.r2 - vbox.r1 + 1) * (vbox.g2 - vbox.g1 + 1) * (vbox.b2 - vbox.b1 + 1));
}
return vbox._volume;
},
count: function(force) {
var vbox = this,
histo = vbox.histo;
if (!vbox._count_set || force) {
var npix = 0,
i, j, k;
for (i = vbox.r1; i <= vbox.r2; i++) {
for (j = vbox.g1; j <= vbox.g2; j++) {
for (k = vbox.b1; k <= vbox.b2; k++) {
index = getColorIndex(i,j,k);
npix += (histo[index] || 0);
}
}
}
vbox._count = npix;
vbox._count_set = true;
}
return vbox._count;
},
copy: function() {
var vbox = this;
return new VBox(vbox.r1, vbox.r2, vbox.g1, vbox.g2, vbox.b1, vbox.b2, vbox.histo);
},
avg: function(force) {
var vbox = this,
histo = vbox.histo;
if (!vbox._avg || force) {
var ntot = 0,
mult = 1 << (8 - sigbits),
rsum = 0,
gsum = 0,
bsum = 0,
hval,
i, j, k, histoindex;
for (i = vbox.r1; i <= vbox.r2; i++) {
for (j = vbox.g1; j <= vbox.g2; j++) {
for (k = vbox.b1; k <= vbox.b2; k++) {
histoindex = getColorIndex(i,j,k);
hval = histo[histoindex] || 0;
ntot += hval;
rsum += (hval * (i + 0.5) * mult);
gsum += (hval * (j + 0.5) * mult);
bsum += (hval * (k + 0.5) * mult);
}
}
}
if (ntot) {
vbox._avg = [~~(rsum/ntot), ~~(gsum/ntot), ~~(bsum/ntot)];
} else {
//console.log('empty box');
vbox._avg = [
~~(mult * (vbox.r1 + vbox.r2 + 1) / 2),
~~(mult * (vbox.g1 + vbox.g2 + 1) / 2),
~~(mult * (vbox.b1 + vbox.b2 + 1) / 2)
];
}
}
return vbox._avg;
},
contains: function(pixel) {
var vbox = this,
rval = pixel[0] >> rshift;
gval = pixel[1] >> rshift;
bval = pixel[2] >> rshift;
return (rval >= vbox.r1 && rval <= vbox.r2 &&
gval >= vbox.g1 && gval <= vbox.g2 &&
bval >= vbox.b1 && bval <= vbox.b2);
}
};
// Color map
function CMap() {
this.vboxes = new PQueue(function(a,b) {
return pv.naturalOrder(
a.vbox.count()*a.vbox.volume(),
b.vbox.count()*b.vbox.volume()
)
});;
}
CMap.prototype = {
push: function(vbox) {
this.vboxes.push({
vbox: vbox,
color: vbox.avg()
});
},
palette: function() {
return this.vboxes.map(function(vb) { return vb.color });
},
size: function() {
return this.vboxes.size();
},
map: function(color) {
var vboxes = this.vboxes;
for (var i=0; i<vboxes.size(); i++) {
if (vboxes.peek(i).vbox.contains(color)) {
return vboxes.peek(i).color;
}
}
return this.nearest(color);
},
nearest: function(color) {
var vboxes = this.vboxes,
d1, d2, pColor;
for (var i=0; i<vboxes.size(); i++) {
d2 = Math.sqrt(
Math.pow(color[0] - vboxes.peek(i).color[0], 2) +
Math.pow(color[1] - vboxes.peek(i).color[1], 2) +
Math.pow(color[2] - vboxes.peek(i).color[2], 2)
);
if (d2 < d1 || d1 === undefined) {
d1 = d2;
pColor = vboxes.peek(i).color;
}
}
return pColor;
},
forcebw: function() {
// XXX: won't work yet
var vboxes = this.vboxes;
vboxes.sort(function(a,b) { return pv.naturalOrder(pv.sum(a.color), pv.sum(b.color) )});
// force darkest color to black if everything < 5
var lowest = vboxes[0].color;
if (lowest[0] < 5 && lowest[1] < 5 && lowest[2] < 5)
vboxes[0].color = [0,0,0];
// force lightest color to white if everything > 251
var idx = vboxes.length-1,
highest = vboxes[idx].color;
if (highest[0] > 251 && highest[1] > 251 && highest[2] > 251)
vboxes[idx].color = [255,255,255];
}
};
// histo (1-d array, giving the number of pixels in
// each quantized region of color space), or null on error
function getHisto(pixels) {
var histosize = 1 << (3 * sigbits),
histo = new Array(histosize),
index, rval, gval, bval;
pixels.forEach(function(pixel) {
rval = pixel[0] >> rshift;
gval = pixel[1] >> rshift;
bval = pixel[2] >> rshift;
index = getColorIndex(rval, gval, bval);
histo[index] = (histo[index] || 0) + 1;
});
return histo;
}
function vboxFromPixels(pixels, histo) {
var rmin=1000000, rmax=0,
gmin=1000000, gmax=0,
bmin=1000000, bmax=0,
rval, gval, bval;
// find min/max
pixels.forEach(function(pixel) {
rval = pixel[0] >> rshift;
gval = pixel[1] >> rshift;
bval = pixel[2] >> rshift;
if (rval < rmin) rmin = rval;
else if (rval > rmax) rmax = rval;
if (gval < gmin) gmin = gval;
else if (gval > gmax) gmax = gval;
if (bval < bmin) bmin = bval;
else if (bval > bmax) bmax = bval;
});
return new VBox(rmin, rmax, gmin, gmax, bmin, bmax, histo);
}
function medianCutApply(histo, vbox) {
if (!vbox.count()) return;
var rw = vbox.r2 - vbox.r1 + 1,
gw = vbox.g2 - vbox.g1 + 1,
bw = vbox.b2 - vbox.b1 + 1,
maxw = pv.max([rw, gw, bw]);
// only one pixel, no split
if (vbox.count() == 1) {
return [vbox.copy()]
}
/* Find the partial sum arrays along the selected axis. */
var total = 0,
partialsum = [],
lookaheadsum = [],
i, j, k, sum, index;
if (maxw == rw) {
for (i = vbox.r1; i <= vbox.r2; i++) {
sum = 0;
for (j = vbox.g1; j <= vbox.g2; j++) {
for (k = vbox.b1; k <= vbox.b2; k++) {
index = getColorIndex(i,j,k);
sum += (histo[index] || 0);
}
}
total += sum;
partialsum[i] = total;
}
}
else if (maxw == gw) {
for (i = vbox.g1; i <= vbox.g2; i++) {
sum = 0;
for (j = vbox.r1; j <= vbox.r2; j++) {
for (k = vbox.b1; k <= vbox.b2; k++) {
index = getColorIndex(j,i,k);
sum += (histo[index] || 0);
}
}
total += sum;
partialsum[i] = total;
}
}
else { /* maxw == bw */
for (i = vbox.b1; i <= vbox.b2; i++) {
sum = 0;
for (j = vbox.r1; j <= vbox.r2; j++) {
for (k = vbox.g1; k <= vbox.g2; k++) {
index = getColorIndex(j,k,i);
sum += (histo[index] || 0);
}
}
total += sum;
partialsum[i] = total;
}
}
partialsum.forEach(function(d,i) {
lookaheadsum[i] = total-d
});
function doCut(color) {
var dim1 = color + '1',
dim2 = color + '2',
left, right, vbox1, vbox2, d2, count2=0;
for (i = vbox[dim1]; i <= vbox[dim2]; i++) {
if (partialsum[i] > total / 2) {
vbox1 = vbox.copy();
vbox2 = vbox.copy();
left = i - vbox[dim1];
right = vbox[dim2] - i;
if (left <= right)
d2 = Math.min(vbox[dim2] - 1, ~~(i + right / 2));
else d2 = Math.max(vbox[dim1], ~~(i - 1 - left / 2));
// avoid 0-count boxes
while (!partialsum[d2]) d2++;
count2 = lookaheadsum[d2];
while (!count2 && partialsum[d2-1]) count2 = lookaheadsum[--d2];
// set dimensions
vbox1[dim2] = d2;
vbox2[dim1] = vbox1[dim2] + 1;
//console.log('vbox counts:', vbox.count(), vbox1.count(), vbox2.count());
return [vbox1, vbox2];
}
}
}
// determine the cut planes
return maxw == rw ? doCut('r') :
maxw == gw ? doCut('g') :
doCut('b');
}
function quantize(pixels, maxcolors) {
// short-circuit
if (!pixels.length || maxcolors < 2 || maxcolors > 256) {
//console.log('wrong number of maxcolors');
return false;
}
// XXX: check color content and convert to grayscale if insufficient
var histo = getHisto(pixels),
histosize = 1 << (3 * sigbits);
// check that we aren't below maxcolors already
var nColors = 0;
histo.forEach(function() { nColors++ });
if (nColors <= maxcolors) {
// XXX: generate the new colors from the histo and return
}
// get the beginning vbox from the colors
var vbox = vboxFromPixels(pixels, histo),
pq = new PQueue(function(a,b) { return pv.naturalOrder(a.count(), b.count()) });
pq.push(vbox);
// inner function to do the iteration
function iter(lh, target) {
var ncolors = 1,
niters = 0,
vbox;
while (niters < maxIterations) {
vbox = lh.pop();
if (!vbox.count()) { /* just put it back */
lh.push(vbox);
niters++;
continue;
}
// do the cut
var vboxes = medianCutApply(histo, vbox),
vbox1 = vboxes[0],
vbox2 = vboxes[1];
if (!vbox1) {
//console.log("vbox1 not defined; shouldn't happen!");
return;
}
lh.push(vbox1);
if (vbox2) { /* vbox2 can be null */
lh.push(vbox2);
ncolors++;
}
if (ncolors >= target) return;
if (niters++ > maxIterations) {
//console.log("infinite loop; perhaps too few pixels!");
return;
}
}
}
// first set of colors, sorted by population
iter(pq, fractByPopulations * maxcolors);
// //console.log(pq.size(), pq.debug().length, pq.debug().slice());
// Re-sort by the product of pixel occupancy times the size in color space.
var pq2 = new PQueue(function(a,b) {
return pv.naturalOrder(a.count()*a.volume(), b.count()*b.volume())
});
while (pq.size()) {
pq2.push(pq.pop());
}
// next set - generate the median cuts using the (npix * vol) sorting.
iter(pq2, maxcolors - pq2.size());
// calculate the actual colors
var cmap = new CMap();
while (pq2.size()) {
cmap.push(pq2.pop());
}
return cmap;
}
return {
quantize: quantize
}
})();
/*!
* Color Thief v2.0
* by Lokesh Dhakar - http://www.lokeshdhakar.com
*
* License
* -------
* Creative Commons Attribution 2.5 License:
* http://creativecommons.org/licenses/by/2.5/
*
* Thanks
* ------
* Nick Rabinowitz - For creating quantize.js.
* John Schulz - For clean up and optimization. @JFSIII
* Nathan Spady - For adding drag and drop support to the demo page.
*
*/
/*
CanvasImage Class
Class that wraps the html image element and canvas.
It also simplifies some of the canvas context manipulation
with a set of helper functions.
*/
var CanvasImage = function (image) {
this.canvas = document.createElement('canvas');
this.context = this.canvas.getContext('2d');
document.body.appendChild(this.canvas);
this.width = this.canvas.width = image.width;
this.height = this.canvas.height = image.height;
this.context.drawImage(image, 0, 0, this.width, this.height);
};
CanvasImage.prototype.clear = function () {
this.context.clearRect(0, 0, this.width, this.height);
};
CanvasImage.prototype.update = function (imageData) {
this.context.putImageData(imageData, 0, 0);
};
CanvasImage.prototype.getPixelCount = function () {
return this.width * this.height;
};
CanvasImage.prototype.getImageData = function () {
return this.context.getImageData(0, 0, this.width, this.height);
};
CanvasImage.prototype.removeCanvas = function () {
this.canvas.parentNode.removeChild(this.canvas);
};
var ColorThief = function () {};
/*
* getColor(sourceImage[, quality])
* returns {r: num, g: num, b: num}
*
* Use the median cut algorithm provided by quantize.js to cluster similar
* colors and return the base color from the largest cluster.
*
* Quality is an optional argument. It needs to be an integer. 0 is the highest quality settings.
* 10 is the default. There is a trade-off between quality and speed. The bigger the number, the
* faster a color will be returned but the greater the likelihood that it will not be the visually
* most dominant color.
*
* */
ColorThief.prototype.getColor = function(sourceImage, quality) {
var palette = this.getPalette(sourceImage, 5, quality);
var dominantColor = palette[0];
return dominantColor;
};
/*
* getPalette(sourceImage[, colorCount, quality])
* returns array[ {r: num, g: num, b: num}, {r: num, g: num, b: num}, ...]
*
* Use the median cut algorithm provided by quantize.js to cluster similar colors.
*
* colorCount determines the size of the palette; the number of colors returned. If not set, it
* defaults to 10.
*
* BUGGY: Function does not always return the requested amount of colors. It can be +/- 2.
*
* quality is an optional argument. It needs to be an integer. 0 is the highest quality settings.
* 10 is the default. There is a trade-off between quality and speed. The bigger the number, the
* faster the palette generation but the greater the likelihood that colors will be missed.
*
*
*/
ColorThief.prototype.getPalette = function(sourceImage, colorCount, quality) {
if (typeof colorCount === 'undefined') {
colorCount = 10;
}
if (typeof quality === 'undefined') {
quality = 10;
}
// Create custom CanvasImage object
var image = new CanvasImage(sourceImage);
var imageData = image.getImageData();
var pixels = imageData.data;
var pixelCount = image.getPixelCount();
// Store the RGB values in an array format suitable for quantize function
var pixelArray = [];
for (var i = 0, offset, r, g, b, a; i < pixelCount; i = i + quality) {
offset = i * 4;
r = pixels[offset + 0];
g = pixels[offset + 1];
b = pixels[offset + 2];
a = pixels[offset + 3];
// If pixel is mostly opaque and not white
if (a >= 125) {
if (!(r > 250 && g > 250 && b > 250)) {
pixelArray.push([r, g, b]);
}
}
}
// Send array to quantize function which clusters values
// using median cut algorithm
var cmap = MMCQ.quantize(pixelArray, colorCount);
var palette = cmap.palette();
// Clean up
image.removeCanvas();
return palette;
};
/*!
* quantize.js Copyright 2008 Nick Rabinowitz.
* Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php
*/
// fill out a couple protovis dependencies
/*!
* Block below copied from Protovis: http://mbostock.github.com/protovis/
* Copyright 2010 Stanford Visualization Group
* Licensed under the BSD License: http://www.opensource.org/licenses/bsd-license.php
*/
if (!pv) {
var pv = {
map: function(array, f) {
var o = {};
return f ? array.map(function(d, i) { o.index = i; return f.call(o, d); }) : array.slice();
},
naturalOrder: function(a, b) {
return (a < b) ? -1 : ((a > b) ? 1 : 0);
},
sum: function(array, f) {
var o = {};
return array.reduce(f ? function(p, d, i) { o.index = i; return p + f.call(o, d); } : function(p, d) { return p + d; }, 0);
},
max: function(array, f) {
return Math.max.apply(null, f ? pv.map(array, f) : array);
}
};
}
/**
* Basic Javascript port of the MMCQ (modified median cut quantization)
* algorithm from the Leptonica library (http://www.leptonica.com/).
* Returns a color map you can use to map original pixels to the reduced
* palette. Still a work in progress.
*
* @author Nick Rabinowitz
* @example
// array of pixels as [R,G,B] arrays
var myPixels = [[190,197,190], [202,204,200], [207,214,210], [211,214,211], [205,207,207]
// etc
];
var maxColors = 4;
var cmap = MMCQ.quantize(myPixels, maxColors);
var newPalette = cmap.palette();
var newPixels = myPixels.map(function(p) {
return cmap.map(p);
});
*/
var MMCQ = (function() {
// private constants
var sigbits = 5,
rshift = 8 - sigbits,
maxIterations = 1000,
fractByPopulations = 0.75;
// get reduced-space color index for a pixel
function getColorIndex(r, g, b) {
return (r << (2 * sigbits)) + (g << sigbits) + b;
}
// Simple priority queue
function PQueue(comparator) {
var contents = [],
sorted = false;
function sort() {
contents.sort(comparator);
sorted = true;
}
return {
push: function(o) {
contents.push(o);
sorted = false;
},
peek: function(index) {
if (!sorted) sort();
if (index===undefined) index = contents.length - 1;
return contents[index];
},
pop: function() {
if (!sorted) sort();
return contents.pop();
},
size: function() {
return contents.length;
},
map: function(f) {
return contents.map(f);
},
debug: function() {
if (!sorted) sort();
return contents;
}
};
}
// 3d color space box
function VBox(r1, r2, g1, g2, b1, b2, histo) {
var vbox = this;
vbox.r1 = r1;
vbox.r2 = r2;
vbox.g1 = g1;
vbox.g2 = g2;
vbox.b1 = b1;
vbox.b2 = b2;
vbox.histo = histo;
}
VBox.prototype = {
volume: function(force) {
var vbox = this;
if (!vbox._volume || force) {
vbox._volume = ((vbox.r2 - vbox.r1 + 1) * (vbox.g2 - vbox.g1 + 1) * (vbox.b2 - vbox.b1 + 1));
}
return vbox._volume;
},
count: function(force) {
var vbox = this,
histo = vbox.histo;
if (!vbox._count_set || force) {
var npix = 0,
i, j, k;
for (i = vbox.r1; i <= vbox.r2; i++) {
for (j = vbox.g1; j <= vbox.g2; j++) {
for (k = vbox.b1; k <= vbox.b2; k++) {
index = getColorIndex(i,j,k);
npix += (histo[index] || 0);
}
}
}
vbox._count = npix;
vbox._count_set = true;
}
return vbox._count;
},
copy: function() {
var vbox = this;
return new VBox(vbox.r1, vbox.r2, vbox.g1, vbox.g2, vbox.b1, vbox.b2, vbox.histo);
},
avg: function(force) {
var vbox = this,
histo = vbox.histo;
if (!vbox._avg || force) {
var ntot = 0,
mult = 1 << (8 - sigbits),
rsum = 0,
gsum = 0,
bsum = 0,
hval,
i, j, k, histoindex;
for (i = vbox.r1; i <= vbox.r2; i++) {
for (j = vbox.g1; j <= vbox.g2; j++) {
for (k = vbox.b1; k <= vbox.b2; k++) {
histoindex = getColorIndex(i,j,k);
hval = histo[histoindex] || 0;
ntot += hval;
rsum += (hval * (i + 0.5) * mult);
gsum += (hval * (j + 0.5) * mult);
bsum += (hval * (k + 0.5) * mult);
}
}
}
if (ntot) {
vbox._avg = [~~(rsum/ntot), ~~(gsum/ntot), ~~(bsum/ntot)];
} else {
// console.log('empty box');
vbox._avg = [
~~(mult * (vbox.r1 + vbox.r2 + 1) / 2),
~~(mult * (vbox.g1 + vbox.g2 + 1) / 2),
~~(mult * (vbox.b1 + vbox.b2 + 1) / 2)
];
}
}
return vbox._avg;
},
contains: function(pixel) {
var vbox = this,
rval = pixel[0] >> rshift;
gval = pixel[1] >> rshift;
bval = pixel[2] >> rshift;
return (rval >= vbox.r1 && rval <= vbox.r2 &&
gval >= vbox.g1 && gval <= vbox.g2 &&
bval >= vbox.b1 && bval <= vbox.b2);
}
};
// Color map
function CMap() {
this.vboxes = new PQueue(function(a,b) {
return pv.naturalOrder(
a.vbox.count()*a.vbox.volume(),
b.vbox.count()*b.vbox.volume()
);
});
}
CMap.prototype = {
push: function(vbox) {
this.vboxes.push({
vbox: vbox,
color: vbox.avg()
});
},
palette: function() {
return this.vboxes.map(function(vb) { return vb.color; });
},
size: function() {
return this.vboxes.size();
},
map: function(color) {
var vboxes = this.vboxes;
for (var i=0; i<vboxes.size(); i++) {
if (vboxes.peek(i).vbox.contains(color)) {
return vboxes.peek(i).color;
}
}
return this.nearest(color);
},
nearest: function(color) {
var vboxes = this.vboxes,
d1, d2, pColor;
for (var i=0; i<vboxes.size(); i++) {
d2 = Math.sqrt(
Math.pow(color[0] - vboxes.peek(i).color[0], 2) +
Math.pow(color[1] - vboxes.peek(i).color[1], 2) +
Math.pow(color[2] - vboxes.peek(i).color[2], 2)
);
if (d2 < d1 || d1 === undefined) {
d1 = d2;
pColor = vboxes.peek(i).color;
}
}
return pColor;
},
forcebw: function() {
// XXX: won't work yet
var vboxes = this.vboxes;
vboxes.sort(function(a,b) { return pv.naturalOrder(pv.sum(a.color), pv.sum(b.color));});
// force darkest color to black if everything < 5
var lowest = vboxes[0].color;
if (lowest[0] < 5 && lowest[1] < 5 && lowest[2] < 5)
vboxes[0].color = [0,0,0];
// force lightest color to white if everything > 251
var idx = vboxes.length-1,
highest = vboxes[idx].color;
if (highest[0] > 251 && highest[1] > 251 && highest[2] > 251)
vboxes[idx].color = [255,255,255];
}
};
// histo (1-d array, giving the number of pixels in
// each quantized region of color space), or null on error
function getHisto(pixels) {
var histosize = 1 << (3 * sigbits),
histo = new Array(histosize),
index, rval, gval, bval;
pixels.forEach(function(pixel) {
rval = pixel[0] >> rshift;
gval = pixel[1] >> rshift;
bval = pixel[2] >> rshift;
index = getColorIndex(rval, gval, bval);
histo[index] = (histo[index] || 0) + 1;
});
return histo;
}
function vboxFromPixels(pixels, histo) {
var rmin=1000000, rmax=0,
gmin=1000000, gmax=0,
bmin=1000000, bmax=0,
rval, gval, bval;
// find min/max
pixels.forEach(function(pixel) {
rval = pixel[0] >> rshift;
gval = pixel[1] >> rshift;
bval = pixel[2] >> rshift;
if (rval < rmin) rmin = rval;
else if (rval > rmax) rmax = rval;
if (gval < gmin) gmin = gval;
else if (gval > gmax) gmax = gval;
if (bval < bmin) bmin = bval;
else if (bval > bmax) bmax = bval;
});
return new VBox(rmin, rmax, gmin, gmax, bmin, bmax, histo);
}
function medianCutApply(histo, vbox) {
if (!vbox.count()) return;
var rw = vbox.r2 - vbox.r1 + 1,
gw = vbox.g2 - vbox.g1 + 1,
bw = vbox.b2 - vbox.b1 + 1,
maxw = pv.max([rw, gw, bw]);
// only one pixel, no split
if (vbox.count() == 1) {
return [vbox.copy()];
}
/* Find the partial sum arrays along the selected axis. */
var total = 0,
partialsum = [],
lookaheadsum = [],
i, j, k, sum, index;
if (maxw == rw) {
for (i = vbox.r1; i <= vbox.r2; i++) {
sum = 0;
for (j = vbox.g1; j <= vbox.g2; j++) {
for (k = vbox.b1; k <= vbox.b2; k++) {
index = getColorIndex(i,j,k);
sum += (histo[index] || 0);
}
}
total += sum;
partialsum[i] = total;
}
}
else if (maxw == gw) {
for (i = vbox.g1; i <= vbox.g2; i++) {
sum = 0;
for (j = vbox.r1; j <= vbox.r2; j++) {
for (k = vbox.b1; k <= vbox.b2; k++) {
index = getColorIndex(j,i,k);
sum += (histo[index] || 0);
}
}
total += sum;
partialsum[i] = total;
}
}
else { /* maxw == bw */
for (i = vbox.b1; i <= vbox.b2; i++) {
sum = 0;
for (j = vbox.r1; j <= vbox.r2; j++) {
for (k = vbox.g1; k <= vbox.g2; k++) {
index = getColorIndex(j,k,i);
sum += (histo[index] || 0);
}
}
total += sum;
partialsum[i] = total;
}
}
partialsum.forEach(function(d,i) {
lookaheadsum[i] = total-d;
});
function doCut(color) {
var dim1 = color + '1',
dim2 = color + '2',
left, right, vbox1, vbox2, d2, count2=0;
for (i = vbox[dim1]; i <= vbox[dim2]; i++) {
if (partialsum[i] > total / 2) {
vbox1 = vbox.copy();
vbox2 = vbox.copy();
left = i - vbox[dim1];
right = vbox[dim2] - i;
if (left <= right)
d2 = Math.min(vbox[dim2] - 1, ~~(i + right / 2));
else d2 = Math.max(vbox[dim1], ~~(i - 1 - left / 2));
// avoid 0-count boxes
while (!partialsum[d2]) d2++;
count2 = lookaheadsum[d2];
while (!count2 && partialsum[d2-1]) count2 = lookaheadsum[--d2];
// set dimensions
vbox1[dim2] = d2;
vbox2[dim1] = vbox1[dim2] + 1;
// console.log('vbox counts:', vbox.count(), vbox1.count(), vbox2.count());
return [vbox1, vbox2];
}
}
}
// determine the cut planes
return maxw == rw ? doCut('r') :
maxw == gw ? doCut('g') :
doCut('b');
}
function quantize(pixels, maxcolors) {
// short-circuit
if (!pixels.length || maxcolors < 2 || maxcolors > 256) {
// console.log('wrong number of maxcolors');
return false;
}
// XXX: check color content and convert to grayscale if insufficient
var histo = getHisto(pixels),
histosize = 1 << (3 * sigbits);
// check that we aren't below maxcolors already
var nColors = 0;
histo.forEach(function() { nColors++; });
if (nColors <= maxcolors) {
// XXX: generate the new colors from the histo and return
}
// get the beginning vbox from the colors
var vbox = vboxFromPixels(pixels, histo),
pq = new PQueue(function(a,b) { return pv.naturalOrder(a.count(), b.count()); });
pq.push(vbox);
// inner function to do the iteration
function iter(lh, target) {
var ncolors = 1,
niters = 0,
vbox;
while (niters < maxIterations) {
vbox = lh.pop();
if (!vbox.count()) { /* just put it back */
lh.push(vbox);
niters++;
continue;
}
// do the cut
var vboxes = medianCutApply(histo, vbox),
vbox1 = vboxes[0],
vbox2 = vboxes[1];
if (!vbox1) {
// console.log("vbox1 not defined; shouldn't happen!");
return;
}
lh.push(vbox1);
if (vbox2) { /* vbox2 can be null */
lh.push(vbox2);
ncolors++;
}
if (ncolors >= target) return;
if (niters++ > maxIterations) {
// console.log("infinite loop; perhaps too few pixels!");
return;
}
}
}
// first set of colors, sorted by population
iter(pq, fractByPopulations * maxcolors);
// Re-sort by the product of pixel occupancy times the size in color space.
var pq2 = new PQueue(function(a,b) {
return pv.naturalOrder(a.count()*a.volume(), b.count()*b.volume());
});
while (pq.size()) {
pq2.push(pq.pop());
}
// next set - generate the median cuts using the (npix * vol) sorting.
iter(pq2, maxcolors - pq2.size());
// calculate the actual colors
var cmap = new CMap();
while (pq2.size()) {
cmap.push(pq2.pop());
}
return cmap;
}
return {
quantize: quantize
};
})();