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color.js
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color.js
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// 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);
}