nucliweb
10/31/2016 - 8:31 PM

## RGB to HSL and RGB to HSV color model conversion algorithms

RGB to HSL and RGB to HSV color model conversion algorithms

``````/**
* Converts an RGB color value to HSL. Conversion formula
* 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
* 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];
}

/**
* Converts an RGB color value to HSV. Conversion formula
* Assumes r, g, and b are contained in the set [0, 255] and
* returns h, s, and v 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 HSV representation
*/
function rgbToHsv(r, g, b){
r = r/255, g = g/255, b = b/255;
var max = Math.max(r, g, b), min = Math.min(r, g, b);
var h, s, v = max;

var d = max - min;
s = max == 0 ? 0 : d / max;

if(max == min){
h = 0; // achromatic
}else{
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, v];
}

/**
* Converts an HSV color value to RGB. Conversion formula
* Assumes h, s, and v 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  v       The value
* @return  Array           The RGB representation
*/
function hsvToRgb(h, s, v){
var r, g, b;

var i = Math.floor(h * 6);
var f = h * 6 - i;
var p = v * (1 - s);
var q = v * (1 - f * s);
var t = v * (1 - (1 - f) * s);

switch(i % 6){
case 0: r = v, g = t, b = p; break;
case 1: r = q, g = v, b = p; break;
case 2: r = p, g = v, b = t; break;
case 3: r = p, g = q, b = v; break;
case 4: r = t, g = p, b = v; break;
case 5: r = v, g = p, b = q; break;
}

return [r * 255, g * 255, b * 255];
}``````