107 lines
3.0 KiB
JavaScript
107 lines
3.0 KiB
JavaScript
// Source: https://gist.github.com/uredkar/bd305f2dda9abf5b393d417424777c87#file-cie_rgb_converter-js
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/**
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* Converts CIE color space to RGB color space
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* @param {Number} x
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* @param {Number} y
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* @param {Number} brightness - Ranges from 1 to 254
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* @return {Array} Array that contains the color values for red, green and blue
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*/
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function toRGB(x, y, brightness) {
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//Set to maximum brightness if no custom value was given (Not the slick ECMAScript 6 way for compatibility reasons)
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if (brightness === undefined) {
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brightness = 254;
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}
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var z = 1.0 - x - y;
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var Y = (brightness / 254).toFixed(2);
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var X = (Y / y) * x;
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var Z = (Y / y) * z;
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//Convert to RGB using Wide RGB D65 conversion
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var red = X * 1.656492 - Y * 0.354851 - Z * 0.255038;
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var green = -X * 0.707196 + Y * 1.655397 + Z * 0.036152;
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var blue = X * 0.051713 - Y * 0.121364 + Z * 1.011530;
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//If red, green or blue is larger than 1.0 set it back to the maximum of 1.0
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if (red > blue && red > green && red > 1.0) {
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green = green / red;
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blue = blue / red;
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red = 1.0;
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}
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else if (green > blue && green > red && green > 1.0) {
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red = red / green;
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blue = blue / green;
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green = 1.0;
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}
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else if (blue > red && blue > green && blue > 1.0) {
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red = red / blue;
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green = green / blue;
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blue = 1.0;
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}
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//Reverse gamma correction
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red = red <= 0.0031308 ? 12.92 * red : (1.0 + 0.055) * Math.pow(red, (1.0 / 2.4)) - 0.055;
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green = green <= 0.0031308 ? 12.92 * green : (1.0 + 0.055) * Math.pow(green, (1.0 / 2.4)) - 0.055;
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blue = blue <= 0.0031308 ? 12.92 * blue : (1.0 + 0.055) * Math.pow(blue, (1.0 / 2.4)) - 0.055;
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//Convert normalized decimal to decimal
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red = Math.round(red * 255);
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green = Math.round(green * 255);
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blue = Math.round(blue * 255);
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if (isNaN(red))
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red = 0;
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if (isNaN(green))
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green = 0;
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if (isNaN(blue))
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blue = 0;
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return [red, green, blue];
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}
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/**
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* Converts RGB color space to CIE color space
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* @param {Number} red
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* @param {Number} green
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* @param {Number} blue
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* @return {Array} Array that contains the CIE color values for x and y
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*/
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function toXY(red, green, blue) {
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if (red > 1) { red /= 255; }
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if (green > 1) { green /= 255; }
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if (blue > 1) { blue /= 255; }
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//Apply a gamma correction to the RGB values, which makes the color more vivid and more the like the color displayed on the screen of your device
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var red = (red > 0.04045) ? Math.pow((red + 0.055) / (1.0 + 0.055), 2.4) : (red / 12.92);
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var green = (green > 0.04045) ? Math.pow((green + 0.055) / (1.0 + 0.055), 2.4) : (green / 12.92);
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var blue = (blue > 0.04045) ? Math.pow((blue + 0.055) / (1.0 + 0.055), 2.4) : (blue / 12.92);
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//RGB values to XYZ using the Wide RGB D65 conversion formula
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var X = red * 0.664511 + green * 0.154324 + blue * 0.162028;
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var Y = red * 0.283881 + green * 0.668433 + blue * 0.047685;
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var Z = red * 0.000088 + green * 0.072310 + blue * 0.986039;
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//Calculate the xy values from the XYZ values
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var x = (X / (X + Y + Z)).toFixed(4);
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var y = (Y / (X + Y + Z)).toFixed(4);
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if (isNaN(x))
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x = 0;
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if (isNaN(y))
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y = 0;
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return [x, y];
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}
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