convert Hsl to rgb and hex
Andrew Henderson 
I need a color converter to convert from hsl to rgb and hex value. I am going to do similar like this. I am using jquery and jquery ui range slider for this. Here is my code:
$(function() { $( "#hsl_hue_range" ).slider({ min: 0, max: 100, value: 0, range: false, animate:"slow", orientation: "horizontal", slide: function( event, ui ) { var hsl_hue = ui.value; } });
});
$(function() { $( "#hsl_saturation_range" ).slider({ min: 0, max: 100, value: 0, range: false, animate:"slow", orientation: "horizontal", slide: function( event, ui ) { var hsl_saturation = ui.value; } });
});
$(function() { $( "#hsl_light_range" ).slider({ min: 0, max: 100, value: 0, range: false, animate:"slow", orientation: "horizontal", slide: function( event, ui ) { var hsl_light = ui.value; } });
});I want the solution like this:
the input to converter can be given by the variables. like hsl_hue hsl_saturation hsl_light.
Is there any way to do this?
if no way, what can I do?
6 Answers
New approach (inspired by @Kamil-Kiełczewski solution)
Takes degree, percentage, percentage and returns css hex color:
function hslToHex(h, s, l) { l /= 100; const a = s * Math.min(l, 1 - l) / 100; const f = n => { const k = (n + h / 30) % 12; const color = l - a * Math.max(Math.min(k - 3, 9 - k, 1), -1); return Math.round(255 * color).toString(16).padStart(2, '0'); // convert to Hex and prefix "0" if needed }; return `#${f(0)}${f(8)}${f(4)}`;
}Example:
hslToHex(360, 100, 50) // "#ff0000" -> redOriginal version: (still OK, just longer)
Takes degree, percentage, percentage and returns css hex color:
function hslToHex(h, s, l) { h /= 360; s /= 100; l /= 100; let r, g, b; if (s === 0) { r = g = b = l; // achromatic } else { const 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; }; const q = l < 0.5 ? l * (1 + s) : l + s - l * s; const p = 2 * l - q; r = hue2rgb(p, q, h + 1 / 3); g = hue2rgb(p, q, h); b = hue2rgb(p, q, h - 1 / 3); } const toHex = x => { const hex = Math.round(x * 255).toString(16); return hex.length === 1 ? '0' + hex : hex; }; return `#${toHex(r)}${toHex(g)}${toHex(b)}`;
}Example:
hslToHex(360, 100, 50) // "#ff0000" -> redShortest
Try this (wiki, error analysis, more: rgb2hsl, hsv2rgb rgb2hsv and hsl2hsv)
// input: h in [0,360] and s,v in [0,1] - output: r,g,b in [0,1]
function hsl2rgb(h,s,l)
{ let a= s*Math.min(l,1-l); let f= (n,k=(n+h/30)%12) => l - a*Math.max(Math.min(k-3,9-k,1),-1); return [f(0),f(8),f(4)];
} To calc hsl2hex use rgb2hex(...hsl2rgb(30,1,0.5)). To convert string from format e.g. rgb(255, 255, 255) to hex use rgbStrToHex (which handle empty string case) as follows
// oneliner version
let hsl2rgb = (h,s,l, a=s*Math.min(l,1-l), f= (n,k=(n+h/30)%12) => l - a*Math.max(Math.min(k-3,9-k,1),-1)) => [f(0),f(8),f(4)];
// r,g,b are in [0-1], result e.g. #0812fa.
let rgb2hex = (r,g,b) => "#" + [r,g,b].map(x=>Math.round(x*255).toString(16).padStart(2,0) ).join('');
// hexStr e.g #abcdef, result "rgb(171,205,239)"
let hexStr2rgb = (hexStr) => `rgb(${hexStr.substr(1).match(/../g).map(x=>+`0x${x}`)})`;
// rgb - color str e.g."rgb(12,233,43)", result color hex e.g. "#0ce92b"
let rgbStrToHex= rgb=> '#'+rgb.match(/\d+/g).map(x=>(+x).toString(16).padStart(2,0)).join``
console.log(`hsl: (30,0.2,0.3) --> rgb: (${hsl2rgb(30,0.2,0.3)}) --> hex: ${rgb2hex(...hsl2rgb(30,0.2,0.3))}`);
console.log(`rgb: ${hexStr2rgb("#ff647b")} --> hex: ${rgbStrToHex("rgb(255,100, 123)")}`)
// ---------------
// UX
// ---------------
rgb= [0,0,0];
hs= [0,0,0];
let $ = x => document.querySelector(x);
function changeRGB(i,e) { rgb[i]= hs = rgb2hsl(...rgb); refresh();
}
function changeHS(i,e) { hs[i]=(i?255:1); rgb= hsl2rgb(...hs); refresh();
}
function refresh() { rr = rgb.map(x=>x*255|0).join(', ') hh = rgb2hex(...rgb); tr = `RGB: ${rr}` th = `HSL: ${hs.map((x,i)=>i? (x*100).toFixed(2)+'%':x|0).join(', ')}` thh= `HEX: ${hh}` $('.box').style.backgroundColor=`rgb(${rr})`; $('.infoRGB').innerHTML=`${tr}`; $('.infoHS').innerHTML =`${th}\n${thh}`; $('#r').value=rgb[0]*255; $('#g').value=rgb[1]*255; $('#b').value=rgb[2]*255; $('#h').value=hs[0]; $('#s').value=hs[1]*255; $('#l').value=hs[2]*255;
}
function rgb2hsl(r,g,b) { let a=Math.max(r,g,b), n=a-Math.min(r,g,b), f=(1-Math.abs(a+a-n-1)); let h= n && ((a==r) ? (g-b)/n : ((a==g) ? 2+(b-r)/n : 4+(r-g)/n)); return [60*(h<0?h+6:h), f ? n/f : 0, (a+a-n)/2];
}
refresh();.box { width: 50px; height: 50px; margin: 20px;
}
body { display: flex;
}<div>
<input type="range" min="0" max="255" oninput="changeRGB(0,event)">R<br>
<input type="range" min="0" max="255" oninput="changeRGB(1,event)">G<br>
<input type="range" min="0" max="255" oninput="changeRGB(2,event)">B<br>
<pre></pre>
</div>
<div>
<div></div>
</div>
<div>
<input type="range" min="0" max="360" oninput="changeHS(0,event)">H<br>
<input type="range" min="0" max="255" oninput="changeHS(1,event)">S<br>
<input type="range" min="0" max="255" oninput="changeHS(2,event)">L<br>
<pre></pre><br>
</div>HSL to RGB:
/** * Converts an HSL color value to RGB. Conversion formula * adapted from * 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{ var hue2rgb = 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 [Math.round(r * 255), Math.round(g * 255), Math.round(b * 255)]; }
You can find more information here - HSL to RGB color conversion
Another way to solve this problem is to leverage the window.getComputedStyle capability of modern browsers:
Create an element on the page (it can be hidden, e.g. with
display:none, but that appears to suppress output of the opacity / "A" value)Set a color-valued property of that element using the representation of your choice, e.g.
e.style.color = 'hsla(100, 50%, 75%, 0.8)';(or even named colors like'rebeccapurple')Read the value back using
window.getComputedStyle(e).color. It will be a string of the formrgb(r,g,b)orrgba(r,g,b,a).
I've made a small library that can easily convert colors.
This is my HSL to RGB method, which uses a few other utility methods from the library:
Color.hslToRgb = function(hsl, formatted) { var a, b, g, h, l, p, q, r, ref, s; if (isString(hsl)) { if (!hsl.match(Color.HSL_REGEX)) { return; } ref = hsl.match(/hsla?\((.+?)\)/)[1].split(',').map(function(value) { value.trim(); return parseFloat(value); }), h = ref[0], s = ref[1], l = ref[2], a = ref[3]; } else if ((isObject(hsl)) && (hasKeys(hsl, ['h', 's', 'l']))) { h = hsl.h, s = hsl.s, l = hsl.l, a = hsl.a; } else { return; } h /= 360; s /= 100; l /= 100; if (s === 0) { r = g = b = l; } else { q = l < 0.5 ? l * (1 + s) : l + s - l * s; p = 2 * l - q; r = Color.hueToRgb(p, q, h + 1 / 3); g = Color.hueToRgb(p, q, h); b = Color.hueToRgb(p, q, h - 1 / 3); } return getRgb(Math.round(r * 255), Math.round(g * 255), Math.round(b * 255), a, formatted);
};If you don't want to use npm, the lib can also be found on GitHub.
1I recently had cause to solve this problem and came up with a canvas-based solution. I'm logging it here for posterity only.
In my case I also needed to account for the cumulative effects on the conversion given a range of background colors and a semi-transparent alpha channel...
var HSL2COLOR = function () { return function (hsl, bg) { function checkHex(v) { return 1 === v.length ? '0'+v : v; } var data, r, g, b, a, cnv = document.createElement('canvas'), ctx = cnv.getContext('2d'), alpha = /a\(/.test(hsl), output = {}; return cnv.width = cnv.height = 1, bg && (ctx.fillStyle = bg, ctx.fillRect(0, 0, 1, 1)), ctx.fillStyle = hsl, ctx.fillRect(0, 0, 1, 1), data = ctx.getImageData(0, 0, 1, 1).data, r = data[0], g = data[1], b = data[2], a = (data[3] / 255).toFixed(2), alpha ? (output.hsla = hsl, bg ? output.rgb = 'rgb('+r+','+g+','+b+')' : output.rgba = 'rgb('+r+','+g+','+b+','+a+')') : (output.hsl = hsl, output.rgb = 'rgb('+r+','+g+','+b+')'), output.hex = '#'+checkHex(r.toString(16))+checkHex(g.toString(16))+checkHex(b.toString(16)), output; };
}();
// hsl: no alpha-channel + no background color
console.log(HSL2COLOR('hsl(170, 60%, 45%)'));
/*=> { hsl: "hsl(170, 60%, 45%)", rgb: "rgb(45,183,160)", hex: "#2db7a0" }
*/
// hsla: alpha-channel + no background color
console.log(HSL2COLOR('hsla(170, 60%, 45%, 0.35)'));
/*=> { hsla: "hsla(170, 60%, 45%, 0.35)", rgba: "rgb(42,183,160,0.35)", hex: "#2ab7a0" }
*/
// hsla: alpha-channel + background color
console.log(HSL2COLOR('hsla(170, 60%, 45%, 0.35)','#f00'));
/*=> { hsla: "hsla(170, 60%, 45%, 0.35)", rgb: "rgb(181,64,56)", hex: "#b54038" }
*/As you can see from the results above, HEX values are not particularly representative when there is an alpha-channel in the input but no background color specified - as the canvas basically sees a transparent background as black. Nonetheless, the rgba value remained coherent.
Anyway, I achieved what I needed to, and perhaps this will be of some use to someone, sometime.
BP
