Convert HSB/HSV color to HSL
Stephen Morley seems to have nailed it here.
Specifically:
/* Calculates and stores the HSL components of this HSVColour so that they can
* be returned be the getHSL function.
*/
function calculateHSL(){
// determine the lightness in the range [0,100]
var l = (2 - hsv.s / 100) * hsv.v / 2;
// store the HSL components
hsl =
{
'h' : hsv.h,
's' : hsv.s * hsv.v / (l < 50 ? l * 2 : 200 - l * 2),
'l' : l
};
// correct a division-by-zero error
if (isNaN(hsl.s)) hsl.s = 0;
}
He uses [0-360] for hue and [0-100] for the other values.
I think this is the most precise:
function hsv_to_hsl(h, s, v) {
// both hsv and hsl values are in [0, 1]
var l = (2 - s) * v / 2;
if (l != 0) {
if (l == 1) {
s = 0;
} else if (l < 0.5) {
s = s * v / (l * 2);
} else {
s = s * v / (2 - l * 2);
}
}
return [h, s, l];
}
Short but precise
Try this (s,v,l in [0,1], more: hsv2rgb rgb2hsv and hsl2rgb rgb2hsl)
let hsl2hsv = (h,s,l,v=s*Math.min(l,1-l)+l) => [h, v?2-2*l/v:0, v];
let hsv2hsl = (h,s,v,l=v-v*s/2, m=Math.min(l,1-l)) => [h,m?(v-l)/m:0,l];
let hsv2hsl = (h,s,v,l=v-v*s/2,m=Math.min(l,1-l)) => [h,m?(v-l)/m:0,l];
let hsl2hsv = (h,s,l,v=s*Math.min(l,1-l)+l) => [h, v?2-2*l/v:0, v];
console.log("hsv:["+ hsl2hsv(30,1,0.6) +"] hsl:["+ hsv2hsl(30,0.8,1) +"]");
// -------------------
// UI code
// -------------------
let $ = x => document.querySelector(x);
let c = (x,s) => $(x).style.backgroundColor=s;
let hsl=[0,1,0.5];
let hsv=hsl2hsv(...hsl);
let refreshHSV =(i,e) => {
hsv[i]= e.target.value/(i?100:1);
hsl=hsv2hsl(...hsv);
refreshView();
}
let refreshHSL =(i,e) => {
hsl[i]= e.target.value/(i?100:1);
hsv=hsl2hsv(...hsl);
refreshView();
}
let hsv2rgb = (h,s,v) => {
let f= (n,k=(n+h/60)%6) => v - v*s*Math.max( Math.min(k,4-k,1), 0);
return [f(5),f(3),f(1)];
}
let refreshView = () => {
let a= [hsl[0], (hsl[1]*100).toFixed(2), (hsl[2]*100).toFixed(2)];
let b= [hsv[0], (hsv[1]*100).toFixed(2), (hsv[2]*100).toFixed(2)];
let r= hsv2rgb(...hsv).map(x=>x*255|0);
let ta= `hsl(${a[0]},${a[1]}%,${a[2]}%)`
let tb= `hsv(${b[0]},${b[1]}%,${b[2]}%)`
let tr= `rgb(${r[0]},${r[1]},${r[2]})`
c('.hsl', tr);
$('#sv').value=hsv[1]*100;
$('#v').value =hsv[2]*100;
$('#sl').value=hsl[1]*100;
$('#l').value =hsl[2]*100;
$('.info').innerHTML=`${tr}\n${tb}\n${ta.padEnd(25)}`;
}
refreshView();.box {
width: 50px;
height: 50px;
margin: 20px;
}
body {
display: flex;
background: white;
}<div>
<input id="h" type="range" min="0" max="360" value="0" oninput="refreshHSV(0,event)">Hue<br>
<div class="box hsl"></div>
<pre class="info"></pre>
</div>
<div>
<input id="sv" type="range" min="0" max="100" value="0" oninput="refreshHSV(1,event)">HSV Saturation<br>
<input id="v" type="range" min="0" max="100" value="100" oninput="refreshHSV(2,event)">HSV Value<br><br><br>
<input id="sl" type="range" min="0" max="100" value="0" oninput="refreshHSL(1,event)">HSL Saturation<br>
<input id="l" type="range" min="0" max="100" value="100" oninput="refreshHSL(2,event)">HSL Lightness<br>
</div>This code based on formulas which I discover and write on wiki
