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rgb2hsl/hsl2rgb
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/** | |
* Converts an RGB color value to HSL. Conversion formula | |
* adapted from http://en.wikipedia.org/wiki/HSL_color_space. | |
* Assumes r, g, and b are contained in the set [0, 255] and | |
* returns h, s, and l in the set [0, 1]. | |
* | |
* @param Number r The red color value | |
* @param Number g The green color value | |
* @param Number b The blue color value | |
* @return Array The HSL representation | |
*/ | |
function rgbToHsl(r, g, b){ | |
r /= 255, g /= 255, b /= 255; | |
var max = Math.max(r, g, b), min = Math.min(r, g, b); | |
var h, s, l = (max + min) / 2; | |
if(max == min){ | |
h = s = 0; // achromatic | |
}else{ | |
var d = max - min; | |
s = l > 0.5 ? d / (2 - max - min) : d / (max + min); | |
switch(max){ | |
case r: h = (g - b) / d + (g < b ? 6 : 0); break; | |
case g: h = (b - r) / d + 2; break; | |
case b: h = (r - g) / d + 4; break; | |
} | |
h /= 6; | |
} | |
return [h, s, l]; | |
} | |
/** | |
* Converts an HSL color value to RGB. Conversion formula | |
* adapted from http://en.wikipedia.org/wiki/HSL_color_space. | |
* Assumes h, s, and l are contained in the set [0, 1] and | |
* returns r, g, and b in the set [0, 255]. | |
* | |
* @param Number h The hue | |
* @param Number s The saturation | |
* @param Number l The lightness | |
* @return Array The RGB representation | |
*/ | |
function hslToRgb(h, s, l){ | |
var r, g, b; | |
if(s == 0){ | |
r = g = b = l; // achromatic | |
}else{ | |
function hue2rgb(p, q, t){ | |
if(t < 0) t += 1; | |
if(t > 1) t -= 1; | |
if(t < 1/6) return p + (q - p) * 6 * t; | |
if(t < 1/2) return q; | |
if(t < 2/3) return p + (q - p) * (2/3 - t) * 6; | |
return p; | |
} | |
var q = l < 0.5 ? l * (1 + s) : l + s - l * s; | |
var p = 2 * l - q; | |
r = hue2rgb(p, q, h + 1/3); | |
g = hue2rgb(p, q, h); | |
b = hue2rgb(p, q, h - 1/3); | |
} | |
return [r * 255, g * 255, b * 255]; | |
} |
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