color-space
Version:
Collection of color space conversions
257 lines (219 loc) • 10.1 kB
JavaScript
/**
* Architects and visual constructors hungarian color space.
*
* http://hej.sze.hu/ARC/ARC-030520-A/arc030520a.pdf
*
* @module color-space/coloroid
*/
import xyy from './xyy.js';
import xyz from './xyz.js';
var coloroid = {
name: 'coloroid',
alias: ['ATV'],
// hue, saturation, luminosity
// note that hue values are ids, not the numbers - not every value is possible
// e.g. 38 will be rounded to 36
channel: ['A', 'T', 'V'],
min: [10, 0, 0],
max: [76, 100, 100],
// Coloroid table
// Regression of values is almost impossible, as hues don’t correlate
// Even angle values are picked very inconsistently, based on aesthetical evaluation.
// - tgф, ctgф are removed, ф is searched instead
// - eλ = xλ + yλ + zλ
// - λ is removed as not used
table: [
//A angle eλ xλ yλ
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/**
* Backwise - from coloroid to xyY
*
* @param {Array<number>} arg Coloroid values
*
* @return {Array<number>} xyY values
*/
xyy: function ([A, T, V]) {
//find the closest row in the table
var row;
for (var i = 0; i < table.length; i++) {
if (A <= table[i][0]) {
row = table[i];
break;
}
}
//FIXME row is possibly undefined
var yl = row[4], el = row[2], xl = row[3];
var Y = V * V / 100;
var Yl = yl * el * 100;
var x = (100 * Y * x0 * ew + 100 * xl * el * T - Yl * T * x0 * ew) / (100 * T * el - Yl * T * ew + 100 * Y * ew);
var y = (100 * Y + 100 * T * yl * el - Yl * T) / (Y * ew * 100 + T * 100 * el - T * Yl * ew);
// var x = (100*Y*ew*x0 + 100*T*el*xl - T*Yl*ew*x0) / (100*T*el - T*Yl*ew + 100*Y*ew);
// var y = 100*Y / (100*T*el + 100*T*ew*Yl + 100*ew*Y);
// var x = (ew*x0*(V*V - 100*T*row[6]) + 100*T*el*xl) / (ew*(V*V - 100*T*row[6]) + 100*T*el);
// var y = V*V/(ew*(V*V + 100*T*row[6]) + 100*T*el);
return [x, y, Y];
}
};
/**
Coloroid table source
Some negative angle typos are fixed.
Angle typo on the A=62 is fixed.
xλ typo on A=73 is fixed.
Beware, tg/ctg values don’t agree with angle.
Also don’t trust the calculated eλ = xλ + yλ + zλ.
Also, unfortunately, some values might be wrong, as coloroid range looks uneven.
A λ ф tg ф ctg ф xλ yλ zλ xλ yλ eλ
10 570.83 59.0 0.6009 0.775745 0.946572 0.002032 0.44987 0.54895 1.724349
11 572.64 55.3 0.6924 0.805130 0.933804 0.001910 0.46248 0.53641 1.740845
12 574.38 51.7 0.7898 0.832782 0.920395 0.001808 0.47451 0.52444 1.754986
13 576.06 48.2 1.1180 0.8941 0.858841 0.906482 0.001764 0.48601 0.51298 1.767088
14 577.50 44.8 0.9330 1.0070 0.880488 0.893741 0.001724 0.49578 0.50325 1.775953
15 579.31 41.5 0.8847 0.906652 0.876749 0.001672 0.50790 0.49052 1.785074
16 580.95 38.2 0.7869 0.929124 0.860368 0.001612 0.51874 0.43035 1.791104
20 582.65 34.9 0.6976 0.950909 0.842391 0.001531 0.52980 0.46934 1.794831
21 584.46 31.5 0.6128 0.972454 0.824779 0.001431 0.54137 0.45783 1.798665
22 586.43 28.0 0.5317 0.993753 0.799758 0.001308 0.55367 0.44559 1.794822
23 588.59 24.4 0.4536 1.014350 0.774090 0.001170 0.56680 0.43253 1.789610
24 591.06 20.6 0.3759 1.034402 0.774014 0.001067 0.58128 0.41811 1.779484
25 594.00 16.6 0.2974 1.052466 0.707496 0.001021 0.59766 0.40176 1.760984
26 597.74 12.3 0.2180 1.062544 0.660001 0.000898 0.61653 0.38300 1.723444
30 602.72 7.7 0.1352 1.056125 0.596070 0.000696 0.63896 0.36061 1.652892
31 610.14 2.8 0.0489 1.001027 0.501245 0.000335 0.66619 0.33358 1.502608
32 625.00 -2.5 -0.0435 0.751400 0.321000 0.000100 0.70061 0.29930 1.072500
33 -492.79 -8.4 -0.1477 0.726603 0.304093 0.105941 0.63925 0.26753 1.136638
34 -495.28 -19.8 -0.3600 0.689620 0.278886 0.263780 0.53962 0.22631 1.232286
35 -498.45 -31.6 -0.6152 0.659523 0.258373 0.392224 0.50340 0.19721 1.310122
40 -502.69 -43.2 -0.9391 0.633815 0.240851 0.501944 0.46041 0.17495 1.376610
41 -509.12 -54.6 -0.7107 0.609810 0.224490 0.604392 0.42386 0.15603 1.438692
42 -520.40 -65.8 -0.4494 0.585492 0.207915 0.708175 0.38991 0.13846 1.501583
43 -536.31 -76.8 -0.2345 0.558865 0.189767 0.821815 0.35586 0.12083 1.570447
44 -548.11 -86.8 -0.0559 0.529811 0.169965 0.945807 0.32195 0.10328 1.645584
45 -555.96 -95.8 -0.1016 0.496364 0.147168 1.088551 0.28657 0.08496 1.732085
46 -564.18 -108.4 0.3327 0.425346 0.098764 1.391643 0.22202 0.05155 1.915754
50 450.00 -117.2 0.5141 0.336200 0.038000 1.772110 0.15664 0.01771 2.146310
51 468.71 -124.7 0.6924 0.210174 0.086198 1.353567 0.12736 0.05227 1.649940
52 475.44 -131.8 0.8941 0.137734 0.114770 1.020911 0.10813 0.09020 1.273415
53 479.00 -138.5 0.8847 0.101787 0.135067 0.843955 0.09414 0.12506 1.080809
54 482.04 -145.1 0.6976 0.079004 0.150709 0.727363 0.03249 0.15741 0.957577
55 484.29 -152.0 0.5317 0.062658 0.164626 0.641692 0.07206 0.18958 0.868977
56 487.31 -163.4 0.2981 0.044691 0.185949 0.541091 0.05787 0.24109 0.771732
60 490.40 -177.2 0.0489 0.030372 0.211659 0.455077 0.04353 0.30378 0.697110
61 492.72 171.6 -0.1477 0.021655 0.234022 0.400126 0.03291 0.35696 0.655804
62 495.28 125.4 -0.3600 0.013989 0.261843 0.348126 0.02240 0.41971 0.623969
63 498.45 148.4 -0.6152 0.007215 0.301137 0.287685 0.01196 0.49954 0.596037
64 502.69 136.8 -0.9391 -1.0650 0.002586 0.366425 0.238402 0.00425 0.60321 0.607414
65 509.12 125.4 -1.4070 -0.7107 0.007260 0.485346 0.167317 0.01099 0.73542 0.659924
66 520.40 114.2 -0.4494 0.066010 0.717274 0.076233 0.08050 0.83391 0.859523
70 536.31 103.2 -0.2345 0.242272 0.926325 0.027086 0.20259 0.77474 1.195684
71 548.11 93.2 -0.0559 0.406663 0.990587 0.010284 0.28807 0.70460 1.410097
72 555.96 84.2 0.1016 0.527646 0.999862 0.005321 0.34422 0.65230 1.532830
73 560.74 77.3 0.2254 0.606873 0.993224 0.003695 0.37838 0.61930 1.603793
74 564.18 71.6 0.3327 0.664599 0.981981 0.002868 0.40290 0.59533 1.649449
75 566.78 66.9 0.4265 0.708358 0.970252 0.002470 0.42141 0.57716 1.681081
76 568.92 62.8 0.5140 0.744182 0.958592 0.002205 0.43647 0.56222 1.704981
*/
// Create angle-sorted table
var table = coloroid.table;
var angleTable = table.slice(-13).concat(table.slice(0, -13));
// Some precalculations
// 2° D65 whitepoint is used
var i = 'D65';
var o = 2;
var Xn = xyz.whitepoint[o][i][0];
var Yn = xyz.whitepoint[o][i][1];
var Zn = xyz.whitepoint[o][i][2];
var y0 = Xn / (Xn + Yn + Zn);
var x0 = Yn / (Xn + Yn + Zn);
var ew = (Xn + Yn + Zn) / 100;
/**
* From xyY to coloroid
*
* @param {Array<number>} arg xyY tuple
*
* @return {Array<number>} ATV coloroid channels
*/
xyy.coloroid = function (arg) {
var x = arg[0], y = arg[1], Y = arg[2];
//coloroid luminocity is the same as hunter-lab lightness (the easier part)
var V = 10 * Math.sqrt(Y);
//get the hue angle, -π ... +π
var angle = Math.atan2(y - y0, x - x0) * 180 / Math.PI;
var row;
//find the closest row in the table
var prev = angleTable.length - 1;
for (var i = 0; i < angleTable.length; i++) {
if (angle > angleTable[i][1]) {
break;
}
prev = i;
}
//round instead of ceil
row = Math.abs(angleTable[i + 1][1] - angle) > Math.abs(angleTable[prev][1] - angle) ? angleTable[i + 1] : angleTable[prev];
//get hue id
var A = row[0];
//calc saturation
var yl = row[4], el = row[2], xl = row[3];
//yl should be scaled to 0..100;
var Yl = yl * el * 100;
var T = 100 * Y * (x0 * ew - x * ew) / (100 * (x * el - xl * el) + Yl * (x0 * ew - x * ew));
// var T = 100 * Y*(1 - y*ew) / (100*(y*el - yl*el) + Yl*(1 - y*ew));
return [A, T, V];
};
/**
* Proper transformation to a XYZ (via xyY)
**/
xyz.coloroid = function (arg) {
return xyy.coloroid(xyz.xyy(arg));
};
coloroid.xyz = function (arg) {
return xyy.xyz(coloroid.xyy(arg));
};
export default coloroid;