util.js

// the following functions are based off of the pseudocode
// found on www.easyrgb.com

function lab2rgb(lab){
    var y = (lab[0] + 16) / 116,
        x = lab[1] / 500 + y,
        z = y - lab[2] / 200,
        r, g, b;
  
    x = 0.95047 * ((x * x * x > 0.008856) ? x * x * x : (x - 16/116) / 7.787);
    y = 1.00000 * ((y * y * y > 0.008856) ? y * y * y : (y - 16/116) / 7.787);
    z = 1.08883 * ((z * z * z > 0.008856) ? z * z * z : (z - 16/116) / 7.787);
  
    r = x *  3.2406 + y * -1.5372 + z * -0.4986;
    g = x * -0.9689 + y *  1.8758 + z *  0.0415;
    b = x *  0.0557 + y * -0.2040 + z *  1.0570;
  
    r = (r > 0.0031308) ? (1.055 * Math.pow(r, 1/2.4) - 0.055) : 12.92 * r;
    g = (g > 0.0031308) ? (1.055 * Math.pow(g, 1/2.4) - 0.055) : 12.92 * g;
    b = (b > 0.0031308) ? (1.055 * Math.pow(b, 1/2.4) - 0.055) : 12.92 * b;
  
    return [Math.max(0, Math.min(1, r)) * 255, 
            Math.max(0, Math.min(1, g)) * 255, 
            Math.max(0, Math.min(1, b)) * 255]
  }
  
  
  function rgb2lab(rgb){
    var r = rgb[0] / 255,
        g = rgb[1] / 255,
        b = rgb[2] / 255,
        x, y, z;
  
    r = (r > 0.04045) ? Math.pow((r + 0.055) / 1.055, 2.4) : r / 12.92;
    g = (g > 0.04045) ? Math.pow((g + 0.055) / 1.055, 2.4) : g / 12.92;
    b = (b > 0.04045) ? Math.pow((b + 0.055) / 1.055, 2.4) : b / 12.92;
  
    x = (r * 0.4124 + g * 0.3576 + b * 0.1805) / 0.95047;
    y = (r * 0.2126 + g * 0.7152 + b * 0.0722) / 1.00000;
    z = (r * 0.0193 + g * 0.1192 + b * 0.9505) / 1.08883;
  
    x = (x > 0.008856) ? Math.pow(x, 1/3) : (7.787 * x) + 16/116;
    y = (y > 0.008856) ? Math.pow(y, 1/3) : (7.787 * y) + 16/116;
    z = (z > 0.008856) ? Math.pow(z, 1/3) : (7.787 * z) + 16/116;
  
    return [(116 * y) - 16, 500 * (x - y), 200 * (y - z)]
  }
  
  // calculate the perceptual distance between colors in CIELAB
  // https://github.com/THEjoezack/ColorMine/blob/master/ColorMine/ColorSpaces/Comparisons/Cie94Comparison.cs
  
  function deltaE(labA, labB){
    var deltaL = labA[0] - labB[0];
    var deltaA = labA[1] - labB[1];
    var deltaB = labA[2] - labB[2];
    var c1 = Math.sqrt(labA[1] * labA[1] + labA[2] * labA[2]);
    var c2 = Math.sqrt(labB[1] * labB[1] + labB[2] * labB[2]);
    var deltaC = c1 - c2;
    var deltaH = deltaA * deltaA + deltaB * deltaB - deltaC * deltaC;
    deltaH = deltaH < 0 ? 0 : Math.sqrt(deltaH);
    var sc = 1.0 + 0.045 * c1;
    var sh = 1.0 + 0.015 * c1;
    var deltaLKlsl = deltaL / (1.0);
    var deltaCkcsc = deltaC / (sc);
    var deltaHkhsh = deltaH / (sh);
    var i = deltaLKlsl * deltaLKlsl + deltaCkcsc * deltaCkcsc + deltaHkhsh * deltaHkhsh;
    return i < 0 ? 0 : Math.sqrt(i);
  }
  
  /**!
 * @preserve $.parseColor
 * Copyright 2011 THEtheChad Elliott
 * Released under the MIT and GPL licenses.
 */


// Parse hex/rgb{a} color syntax.
// @input string
// @returns array [r,g,b{,o}]
$.parseColor = function(color) {

  var cache,
      p = parseInt, // Use p as a byte saving reference to parseInt
      color = color.replace(/\s/g,''); // Remove all spaces
  
  // Checks for 6 digit hex and converts string to integer
  if (cache = /#([\da-fA-F]{2})([\da-fA-F]{2})([\da-fA-F]{2})/.exec(color)) 
      cache = [p(cache[1], 16), p(cache[2], 16), p(cache[3], 16)];
      
  // Checks for 3 digit hex and converts string to integer
  else if (cache = /#([\da-fA-F])([\da-fA-F])([\da-fA-F])/.exec(color))
      cache = [p(cache[1], 16) * 17, p(cache[2], 16) * 17, p(cache[3], 16) * 17];
      
  // Checks for rgba and converts string to
  // integer/float using unary + operator to save bytes
  else if (cache = /rgba\(([\d]+),([\d]+),([\d]+),([\d]+|[\d]*.[\d]+)\)/.exec(color))
      cache = [+cache[1], +cache[2], +cache[3], +cache[4]];
      
  // Checks for rgb and converts string to
  // integer/float using unary + operator to save bytes
  else if (cache = /rgb\(([\d]+),([\d]+),([\d]+)\)/.exec(color))
      cache = [+cache[1], +cache[2], +cache[3]];
      
  // Otherwise throw an exception to make debugging easier
  else throw color + ' is not supported by $.parseColor';
  
  // Performs RGBA conversion by default
  isNaN(cache[3]) && (cache[3] = 1);
  
  // Adds or removes 4th value based on rgba support
  // Support is flipped twice to prevent erros if
  // it's not defined
  return cache.slice(0,3 + !!$.support.rgba);
}