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<style>
#cursor { position: fixed; top: -100px; left: -100px; margin-left: -5px; margin-top: -5px; width: 5px; height: 5px; border: 2px solid black; border-radius: 20px;
</style>
<canvas id="hunterlab"></canvas>
<div id="cursor"></div>
<br>
L <input type="range" min="0" max="100" value="100" id="hunter_L">
<br>
a <input type="range" min="-86.185" max="98.294" id="hunter_a">
<br>
b <input type="range" min="-107.863" max="94.482" id="hunter_b">
<br>
<br>
<input type="text" id="selected">
<input type="text" id="hex">
<script>
var xyz = [0,0,0]
var rgb = [0,0,0]
w = hunterlab.width = 512
h = hunterlab.height = 512
ww = w-1, hh = h-1
L_range = [0, 100]
a_range = [-86.185, 98.254]
b_range = [-107.863, 94.482]
ctx = hunterlab.getContext('2d')
ii = jj = -100
down = false
hunter_L.oninput = axis('L')
hunter_a.oninput = axis('a')
hunter_b.oninput = axis('b')
hunterlab.onmousedown = function (e){
e.preventDefault()
down = true
ii = e.clientX - hunterlab.offsetLeft
jj = e.clientY - hunterlab.offsetTop
pick()
}
hunterlab.onmousemove = function(e){
if (! down) return
ii = e.clientX - hunterlab.offsetLeft
jj = e.clientY - hunterlab.offsetTop
pick()
}
document.body.onmouseup = function (e){
down = false
}
function pick () {
x = mix( ii/ww, x_range[0], x_range[1] )
y = mix( jj/hh, y_range[0], y_range[1] )
rgb = xyz2rgb(fn(val, x, y))
selected.value = "rgb(" + rgb.map(Math.round).join(",") + ")"
hex.value = "#" + rgb.map(Math.round).map(function(n){ var s = n.toString(16); return s.length == 1 ? "0"+s : s }).join("")
cursor.style.left = (ii + hunterlab.offsetTop) + "px"
cursor.style.top = (jj + hunterlab.offsetTop) + "px"
}
hunter_a.value = hunter_b.value = 0
mode = "L"
imageData = ctx.createImageData(w,h)
data = imageData.data
axis('L')()
function axis (c) { return function(){ mode = c; paint() } }
function paint () {
var fn_body = (hunterlab2xyz + "").split("{")[1].split("}")[0]
var fn_body = (hunterlab2xyz + "").split("{")[1].split("}")[0]
switch (mode) {
case 'L':
val = parseFloat(hunter_L.value)
x_range = a_range
y_range = b_range
fn = new Function('L','a','b', fn_body)
break
case 'a':
x_range = L_range
val = hunter_a.value
y_range = b_range
fn = new Function('a','L','b', fn_body)
break
case 'b':
x_range = L_range
y_range = a_range
val = hunter_b.value
fn = new Function('b','L','a', fn_body)
break
}
for (var i = 0; i < w; i++) {
for (var j = 0; j < h; j++) {
x = mix( i/ww, x_range[0], x_range[1] )
y = mix( j/hh, y_range[0], y_range[1] )
t = (j*w + i) * 4
rgb = xyz2rgb(fn(val, x, y))
data[t] = Math.round( rgb[0] )
data[t+1] = Math.round( rgb[1] )
data[t+2] = Math.round( rgb[2] )
data[t+3] = 255
}
}
ctx.putImageData(imageData,0,0)
if (ii > -1) { pick() }
}
function mix(n,a,b){ return n*a + (1-n)*b }
function clamp(n,a,b){ return n<a?a:n<b?n:b }
function hunterlab2xyz (L,a,b) {
var_Y = L / 10
var_X = a / 17.5 * L / 10
var_Z = b / 7 * L / 10
Y = Math.pow(var_Y, 2)
X = ( var_X + Y ) / 1.02
Z = -( var_Z - Y ) / 0.847
xyz = [X,Y,Z]
}
function xyz2rgb(){
var var_X = xyz[0] / 100 //X from 0 to 95.047 (Observer = 2°, Illuminant = D65)
var var_Y = xyz[1] / 100 //Y from 0 to 100.000
var var_Z = xyz[2] / 100 //Z from 0 to 108.883
var_R = var_X * 3.2406 + var_Y * -1.5372 + var_Z * -0.4986
var_G = var_X * -0.9689 + var_Y * 1.8758 + var_Z * 0.0415
var_B = var_X * 0.0557 + var_Y * -0.2040 + var_Z * 1.0570
if ( var_R > 0.0031308 ) var_R = 1.055 * Math.pow( var_R, 1 / 2.4 ) - 0.055
else var_R = 12.92 * var_R
if ( var_G > 0.0031308 ) var_G = 1.055 * Math.pow( var_G, 1 / 2.4 ) - 0.055
else var_G = 12.92 * var_G
if ( var_B > 0.0031308 ) var_B = 1.055 * Math.pow( var_B, 1 / 2.4 ) - 0.055
else var_B = 12.92 * var_B
rgb[0] = clamp(var_R * 255, 0, 255)
rgb[1] = clamp(var_G * 255, 0, 255)
rgb[2] = clamp(var_B * 255, 0, 255)
return rgb
}
</script>
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