1/* MIT license */
2/* eslint-disable no-mixed-operators */
3const cssKeywords = require('color-name');
4
5// NOTE: conversions should only return primitive values (i.e. arrays, or
6//       values that give correct `typeof` results).
7//       do not use box values types (i.e. Number(), String(), etc.)
8
9const reverseKeywords = {};
10for (const key of Object.keys(cssKeywords)) {
11	reverseKeywords[cssKeywords[key]] = key;
12}
13
14const convert = {
15	rgb: {channels: 3, labels: 'rgb'},
16	hsl: {channels: 3, labels: 'hsl'},
17	hsv: {channels: 3, labels: 'hsv'},
18	hwb: {channels: 3, labels: 'hwb'},
19	cmyk: {channels: 4, labels: 'cmyk'},
20	xyz: {channels: 3, labels: 'xyz'},
21	lab: {channels: 3, labels: 'lab'},
22	lch: {channels: 3, labels: 'lch'},
23	hex: {channels: 1, labels: ['hex']},
24	keyword: {channels: 1, labels: ['keyword']},
25	ansi16: {channels: 1, labels: ['ansi16']},
26	ansi256: {channels: 1, labels: ['ansi256']},
27	hcg: {channels: 3, labels: ['h', 'c', 'g']},
28	apple: {channels: 3, labels: ['r16', 'g16', 'b16']},
29	gray: {channels: 1, labels: ['gray']}
30};
31
32module.exports = convert;
33
34// Hide .channels and .labels properties
35for (const model of Object.keys(convert)) {
36	if (!('channels' in convert[model])) {
37		throw new Error('missing channels property: ' + model);
38	}
39
40	if (!('labels' in convert[model])) {
41		throw new Error('missing channel labels property: ' + model);
42	}
43
44	if (convert[model].labels.length !== convert[model].channels) {
45		throw new Error('channel and label counts mismatch: ' + model);
46	}
47
48	const {channels, labels} = convert[model];
49	delete convert[model].channels;
50	delete convert[model].labels;
51	Object.defineProperty(convert[model], 'channels', {value: channels});
52	Object.defineProperty(convert[model], 'labels', {value: labels});
53}
54
55convert.rgb.hsl = function (rgb) {
56	const r = rgb[0] / 255;
57	const g = rgb[1] / 255;
58	const b = rgb[2] / 255;
59	const min = Math.min(r, g, b);
60	const max = Math.max(r, g, b);
61	const delta = max - min;
62	let h;
63	let s;
64
65	if (max === min) {
66		h = 0;
67	} else if (r === max) {
68		h = (g - b) / delta;
69	} else if (g === max) {
70		h = 2 + (b - r) / delta;
71	} else if (b === max) {
72		h = 4 + (r - g) / delta;
73	}
74
75	h = Math.min(h * 60, 360);
76
77	if (h < 0) {
78		h += 360;
79	}
80
81	const l = (min + max) / 2;
82
83	if (max === min) {
84		s = 0;
85	} else if (l <= 0.5) {
86		s = delta / (max + min);
87	} else {
88		s = delta / (2 - max - min);
89	}
90
91	return [h, s * 100, l * 100];
92};
93
94convert.rgb.hsv = function (rgb) {
95	let rdif;
96	let gdif;
97	let bdif;
98	let h;
99	let s;
100
101	const r = rgb[0] / 255;
102	const g = rgb[1] / 255;
103	const b = rgb[2] / 255;
104	const v = Math.max(r, g, b);
105	const diff = v - Math.min(r, g, b);
106	const diffc = function (c) {
107		return (v - c) / 6 / diff + 1 / 2;
108	};
109
110	if (diff === 0) {
111		h = 0;
112		s = 0;
113	} else {
114		s = diff / v;
115		rdif = diffc(r);
116		gdif = diffc(g);
117		bdif = diffc(b);
118
119		if (r === v) {
120			h = bdif - gdif;
121		} else if (g === v) {
122			h = (1 / 3) + rdif - bdif;
123		} else if (b === v) {
124			h = (2 / 3) + gdif - rdif;
125		}
126
127		if (h < 0) {
128			h += 1;
129		} else if (h > 1) {
130			h -= 1;
131		}
132	}
133
134	return [
135		h * 360,
136		s * 100,
137		v * 100
138	];
139};
140
141convert.rgb.hwb = function (rgb) {
142	const r = rgb[0];
143	const g = rgb[1];
144	let b = rgb[2];
145	const h = convert.rgb.hsl(rgb)[0];
146	const w = 1 / 255 * Math.min(r, Math.min(g, b));
147
148	b = 1 - 1 / 255 * Math.max(r, Math.max(g, b));
149
150	return [h, w * 100, b * 100];
151};
152
153convert.rgb.cmyk = function (rgb) {
154	const r = rgb[0] / 255;
155	const g = rgb[1] / 255;
156	const b = rgb[2] / 255;
157
158	const k = Math.min(1 - r, 1 - g, 1 - b);
159	const c = (1 - r - k) / (1 - k) || 0;
160	const m = (1 - g - k) / (1 - k) || 0;
161	const y = (1 - b - k) / (1 - k) || 0;
162
163	return [c * 100, m * 100, y * 100, k * 100];
164};
165
166function comparativeDistance(x, y) {
167	/*
168		See https://en.m.wikipedia.org/wiki/Euclidean_distance#Squared_Euclidean_distance
169	*/
170	return (
171		((x[0] - y[0]) ** 2) +
172		((x[1] - y[1]) ** 2) +
173		((x[2] - y[2]) ** 2)
174	);
175}
176
177convert.rgb.keyword = function (rgb) {
178	const reversed = reverseKeywords[rgb];
179	if (reversed) {
180		return reversed;
181	}
182
183	let currentClosestDistance = Infinity;
184	let currentClosestKeyword;
185
186	for (const keyword of Object.keys(cssKeywords)) {
187		const value = cssKeywords[keyword];
188
189		// Compute comparative distance
190		const distance = comparativeDistance(rgb, value);
191
192		// Check if its less, if so set as closest
193		if (distance < currentClosestDistance) {
194			currentClosestDistance = distance;
195			currentClosestKeyword = keyword;
196		}
197	}
198
199	return currentClosestKeyword;
200};
201
202convert.keyword.rgb = function (keyword) {
203	return cssKeywords[keyword];
204};
205
206convert.rgb.xyz = function (rgb) {
207	let r = rgb[0] / 255;
208	let g = rgb[1] / 255;
209	let b = rgb[2] / 255;
210
211	// Assume sRGB
212	r = r > 0.04045 ? (((r + 0.055) / 1.055) ** 2.4) : (r / 12.92);
213	g = g > 0.04045 ? (((g + 0.055) / 1.055) ** 2.4) : (g / 12.92);
214	b = b > 0.04045 ? (((b + 0.055) / 1.055) ** 2.4) : (b / 12.92);
215
216	const x = (r * 0.4124) + (g * 0.3576) + (b * 0.1805);
217	const y = (r * 0.2126) + (g * 0.7152) + (b * 0.0722);
218	const z = (r * 0.0193) + (g * 0.1192) + (b * 0.9505);
219
220	return [x * 100, y * 100, z * 100];
221};
222
223convert.rgb.lab = function (rgb) {
224	const xyz = convert.rgb.xyz(rgb);
225	let x = xyz[0];
226	let y = xyz[1];
227	let z = xyz[2];
228
229	x /= 95.047;
230	y /= 100;
231	z /= 108.883;
232
233	x = x > 0.008856 ? (x ** (1 / 3)) : (7.787 * x) + (16 / 116);
234	y = y > 0.008856 ? (y ** (1 / 3)) : (7.787 * y) + (16 / 116);
235	z = z > 0.008856 ? (z ** (1 / 3)) : (7.787 * z) + (16 / 116);
236
237	const l = (116 * y) - 16;
238	const a = 500 * (x - y);
239	const b = 200 * (y - z);
240
241	return [l, a, b];
242};
243
244convert.hsl.rgb = function (hsl) {
245	const h = hsl[0] / 360;
246	const s = hsl[1] / 100;
247	const l = hsl[2] / 100;
248	let t2;
249	let t3;
250	let val;
251
252	if (s === 0) {
253		val = l * 255;
254		return [val, val, val];
255	}
256
257	if (l < 0.5) {
258		t2 = l * (1 + s);
259	} else {
260		t2 = l + s - l * s;
261	}
262
263	const t1 = 2 * l - t2;
264
265	const rgb = [0, 0, 0];
266	for (let i = 0; i < 3; i++) {
267		t3 = h + 1 / 3 * -(i - 1);
268		if (t3 < 0) {
269			t3++;
270		}
271
272		if (t3 > 1) {
273			t3--;
274		}
275
276		if (6 * t3 < 1) {
277			val = t1 + (t2 - t1) * 6 * t3;
278		} else if (2 * t3 < 1) {
279			val = t2;
280		} else if (3 * t3 < 2) {
281			val = t1 + (t2 - t1) * (2 / 3 - t3) * 6;
282		} else {
283			val = t1;
284		}
285
286		rgb[i] = val * 255;
287	}
288
289	return rgb;
290};
291
292convert.hsl.hsv = function (hsl) {
293	const h = hsl[0];
294	let s = hsl[1] / 100;
295	let l = hsl[2] / 100;
296	let smin = s;
297	const lmin = Math.max(l, 0.01);
298
299	l *= 2;
300	s *= (l <= 1) ? l : 2 - l;
301	smin *= lmin <= 1 ? lmin : 2 - lmin;
302	const v = (l + s) / 2;
303	const sv = l === 0 ? (2 * smin) / (lmin + smin) : (2 * s) / (l + s);
304
305	return [h, sv * 100, v * 100];
306};
307
308convert.hsv.rgb = function (hsv) {
309	const h = hsv[0] / 60;
310	const s = hsv[1] / 100;
311	let v = hsv[2] / 100;
312	const hi = Math.floor(h) % 6;
313
314	const f = h - Math.floor(h);
315	const p = 255 * v * (1 - s);
316	const q = 255 * v * (1 - (s * f));
317	const t = 255 * v * (1 - (s * (1 - f)));
318	v *= 255;
319
320	switch (hi) {
321		case 0:
322			return [v, t, p];
323		case 1:
324			return [q, v, p];
325		case 2:
326			return [p, v, t];
327		case 3:
328			return [p, q, v];
329		case 4:
330			return [t, p, v];
331		case 5:
332			return [v, p, q];
333	}
334};
335
336convert.hsv.hsl = function (hsv) {
337	const h = hsv[0];
338	const s = hsv[1] / 100;
339	const v = hsv[2] / 100;
340	const vmin = Math.max(v, 0.01);
341	let sl;
342	let l;
343
344	l = (2 - s) * v;
345	const lmin = (2 - s) * vmin;
346	sl = s * vmin;
347	sl /= (lmin <= 1) ? lmin : 2 - lmin;
348	sl = sl || 0;
349	l /= 2;
350
351	return [h, sl * 100, l * 100];
352};
353
354// http://dev.w3.org/csswg/css-color/#hwb-to-rgb
355convert.hwb.rgb = function (hwb) {
356	const h = hwb[0] / 360;
357	let wh = hwb[1] / 100;
358	let bl = hwb[2] / 100;
359	const ratio = wh + bl;
360	let f;
361
362	// Wh + bl cant be > 1
363	if (ratio > 1) {
364		wh /= ratio;
365		bl /= ratio;
366	}
367
368	const i = Math.floor(6 * h);
369	const v = 1 - bl;
370	f = 6 * h - i;
371
372	if ((i & 0x01) !== 0) {
373		f = 1 - f;
374	}
375
376	const n = wh + f * (v - wh); // Linear interpolation
377
378	let r;
379	let g;
380	let b;
381	/* eslint-disable max-statements-per-line,no-multi-spaces */
382	switch (i) {
383		default:
384		case 6:
385		case 0: r = v;  g = n;  b = wh; break;
386		case 1: r = n;  g = v;  b = wh; break;
387		case 2: r = wh; g = v;  b = n; break;
388		case 3: r = wh; g = n;  b = v; break;
389		case 4: r = n;  g = wh; b = v; break;
390		case 5: r = v;  g = wh; b = n; break;
391	}
392	/* eslint-enable max-statements-per-line,no-multi-spaces */
393
394	return [r * 255, g * 255, b * 255];
395};
396
397convert.cmyk.rgb = function (cmyk) {
398	const c = cmyk[0] / 100;
399	const m = cmyk[1] / 100;
400	const y = cmyk[2] / 100;
401	const k = cmyk[3] / 100;
402
403	const r = 1 - Math.min(1, c * (1 - k) + k);
404	const g = 1 - Math.min(1, m * (1 - k) + k);
405	const b = 1 - Math.min(1, y * (1 - k) + k);
406
407	return [r * 255, g * 255, b * 255];
408};
409
410convert.xyz.rgb = function (xyz) {
411	const x = xyz[0] / 100;
412	const y = xyz[1] / 100;
413	const z = xyz[2] / 100;
414	let r;
415	let g;
416	let b;
417
418	r = (x * 3.2406) + (y * -1.5372) + (z * -0.4986);
419	g = (x * -0.9689) + (y * 1.8758) + (z * 0.0415);
420	b = (x * 0.0557) + (y * -0.2040) + (z * 1.0570);
421
422	// Assume sRGB
423	r = r > 0.0031308
424		? ((1.055 * (r ** (1.0 / 2.4))) - 0.055)
425		: r * 12.92;
426
427	g = g > 0.0031308
428		? ((1.055 * (g ** (1.0 / 2.4))) - 0.055)
429		: g * 12.92;
430
431	b = b > 0.0031308
432		? ((1.055 * (b ** (1.0 / 2.4))) - 0.055)
433		: b * 12.92;
434
435	r = Math.min(Math.max(0, r), 1);
436	g = Math.min(Math.max(0, g), 1);
437	b = Math.min(Math.max(0, b), 1);
438
439	return [r * 255, g * 255, b * 255];
440};
441
442convert.xyz.lab = function (xyz) {
443	let x = xyz[0];
444	let y = xyz[1];
445	let z = xyz[2];
446
447	x /= 95.047;
448	y /= 100;
449	z /= 108.883;
450
451	x = x > 0.008856 ? (x ** (1 / 3)) : (7.787 * x) + (16 / 116);
452	y = y > 0.008856 ? (y ** (1 / 3)) : (7.787 * y) + (16 / 116);
453	z = z > 0.008856 ? (z ** (1 / 3)) : (7.787 * z) + (16 / 116);
454
455	const l = (116 * y) - 16;
456	const a = 500 * (x - y);
457	const b = 200 * (y - z);
458
459	return [l, a, b];
460};
461
462convert.lab.xyz = function (lab) {
463	const l = lab[0];
464	const a = lab[1];
465	const b = lab[2];
466	let x;
467	let y;
468	let z;
469
470	y = (l + 16) / 116;
471	x = a / 500 + y;
472	z = y - b / 200;
473
474	const y2 = y ** 3;
475	const x2 = x ** 3;
476	const z2 = z ** 3;
477	y = y2 > 0.008856 ? y2 : (y - 16 / 116) / 7.787;
478	x = x2 > 0.008856 ? x2 : (x - 16 / 116) / 7.787;
479	z = z2 > 0.008856 ? z2 : (z - 16 / 116) / 7.787;
480
481	x *= 95.047;
482	y *= 100;
483	z *= 108.883;
484
485	return [x, y, z];
486};
487
488convert.lab.lch = function (lab) {
489	const l = lab[0];
490	const a = lab[1];
491	const b = lab[2];
492	let h;
493
494	const hr = Math.atan2(b, a);
495	h = hr * 360 / 2 / Math.PI;
496
497	if (h < 0) {
498		h += 360;
499	}
500
501	const c = Math.sqrt(a * a + b * b);
502
503	return [l, c, h];
504};
505
506convert.lch.lab = function (lch) {
507	const l = lch[0];
508	const c = lch[1];
509	const h = lch[2];
510
511	const hr = h / 360 * 2 * Math.PI;
512	const a = c * Math.cos(hr);
513	const b = c * Math.sin(hr);
514
515	return [l, a, b];
516};
517
518convert.rgb.ansi16 = function (args, saturation = null) {
519	const [r, g, b] = args;
520	let value = saturation === null ? convert.rgb.hsv(args)[2] : saturation; // Hsv -> ansi16 optimization
521
522	value = Math.round(value / 50);
523
524	if (value === 0) {
525		return 30;
526	}
527
528	let ansi = 30
529		+ ((Math.round(b / 255) << 2)
530		| (Math.round(g / 255) << 1)
531		| Math.round(r / 255));
532
533	if (value === 2) {
534		ansi += 60;
535	}
536
537	return ansi;
538};
539
540convert.hsv.ansi16 = function (args) {
541	// Optimization here; we already know the value and don't need to get
542	// it converted for us.
543	return convert.rgb.ansi16(convert.hsv.rgb(args), args[2]);
544};
545
546convert.rgb.ansi256 = function (args) {
547	const r = args[0];
548	const g = args[1];
549	const b = args[2];
550
551	// We use the extended greyscale palette here, with the exception of
552	// black and white. normal palette only has 4 greyscale shades.
553	if (r === g && g === b) {
554		if (r < 8) {
555			return 16;
556		}
557
558		if (r > 248) {
559			return 231;
560		}
561
562		return Math.round(((r - 8) / 247) * 24) + 232;
563	}
564
565	const ansi = 16
566		+ (36 * Math.round(r / 255 * 5))
567		+ (6 * Math.round(g / 255 * 5))
568		+ Math.round(b / 255 * 5);
569
570	return ansi;
571};
572
573convert.ansi16.rgb = function (args) {
574	let color = args % 10;
575
576	// Handle greyscale
577	if (color === 0 || color === 7) {
578		if (args > 50) {
579			color += 3.5;
580		}
581
582		color = color / 10.5 * 255;
583
584		return [color, color, color];
585	}
586
587	const mult = (~~(args > 50) + 1) * 0.5;
588	const r = ((color & 1) * mult) * 255;
589	const g = (((color >> 1) & 1) * mult) * 255;
590	const b = (((color >> 2) & 1) * mult) * 255;
591
592	return [r, g, b];
593};
594
595convert.ansi256.rgb = function (args) {
596	// Handle greyscale
597	if (args >= 232) {
598		const c = (args - 232) * 10 + 8;
599		return [c, c, c];
600	}
601
602	args -= 16;
603
604	let rem;
605	const r = Math.floor(args / 36) / 5 * 255;
606	const g = Math.floor((rem = args % 36) / 6) / 5 * 255;
607	const b = (rem % 6) / 5 * 255;
608
609	return [r, g, b];
610};
611
612convert.rgb.hex = function (args) {
613	const integer = ((Math.round(args[0]) & 0xFF) << 16)
614		+ ((Math.round(args[1]) & 0xFF) << 8)
615		+ (Math.round(args[2]) & 0xFF);
616
617	const string = integer.toString(16).toUpperCase();
618	return '000000'.substring(string.length) + string;
619};
620
621convert.hex.rgb = function (args) {
622	const match = args.toString(16).match(/[a-f0-9]{6}|[a-f0-9]{3}/i);
623	if (!match) {
624		return [0, 0, 0];
625	}
626
627	let colorString = match[0];
628
629	if (match[0].length === 3) {
630		colorString = colorString.split('').map(char => {
631			return char + char;
632		}).join('');
633	}
634
635	const integer = parseInt(colorString, 16);
636	const r = (integer >> 16) & 0xFF;
637	const g = (integer >> 8) & 0xFF;
638	const b = integer & 0xFF;
639
640	return [r, g, b];
641};
642
643convert.rgb.hcg = function (rgb) {
644	const r = rgb[0] / 255;
645	const g = rgb[1] / 255;
646	const b = rgb[2] / 255;
647	const max = Math.max(Math.max(r, g), b);
648	const min = Math.min(Math.min(r, g), b);
649	const chroma = (max - min);
650	let grayscale;
651	let hue;
652
653	if (chroma < 1) {
654		grayscale = min / (1 - chroma);
655	} else {
656		grayscale = 0;
657	}
658
659	if (chroma <= 0) {
660		hue = 0;
661	} else
662	if (max === r) {
663		hue = ((g - b) / chroma) % 6;
664	} else
665	if (max === g) {
666		hue = 2 + (b - r) / chroma;
667	} else {
668		hue = 4 + (r - g) / chroma;
669	}
670
671	hue /= 6;
672	hue %= 1;
673
674	return [hue * 360, chroma * 100, grayscale * 100];
675};
676
677convert.hsl.hcg = function (hsl) {
678	const s = hsl[1] / 100;
679	const l = hsl[2] / 100;
680
681	const c = l < 0.5 ? (2.0 * s * l) : (2.0 * s * (1.0 - l));
682
683	let f = 0;
684	if (c < 1.0) {
685		f = (l - 0.5 * c) / (1.0 - c);
686	}
687
688	return [hsl[0], c * 100, f * 100];
689};
690
691convert.hsv.hcg = function (hsv) {
692	const s = hsv[1] / 100;
693	const v = hsv[2] / 100;
694
695	const c = s * v;
696	let f = 0;
697
698	if (c < 1.0) {
699		f = (v - c) / (1 - c);
700	}
701
702	return [hsv[0], c * 100, f * 100];
703};
704
705convert.hcg.rgb = function (hcg) {
706	const h = hcg[0] / 360;
707	const c = hcg[1] / 100;
708	const g = hcg[2] / 100;
709
710	if (c === 0.0) {
711		return [g * 255, g * 255, g * 255];
712	}
713
714	const pure = [0, 0, 0];
715	const hi = (h % 1) * 6;
716	const v = hi % 1;
717	const w = 1 - v;
718	let mg = 0;
719
720	/* eslint-disable max-statements-per-line */
721	switch (Math.floor(hi)) {
722		case 0:
723			pure[0] = 1; pure[1] = v; pure[2] = 0; break;
724		case 1:
725			pure[0] = w; pure[1] = 1; pure[2] = 0; break;
726		case 2:
727			pure[0] = 0; pure[1] = 1; pure[2] = v; break;
728		case 3:
729			pure[0] = 0; pure[1] = w; pure[2] = 1; break;
730		case 4:
731			pure[0] = v; pure[1] = 0; pure[2] = 1; break;
732		default:
733			pure[0] = 1; pure[1] = 0; pure[2] = w;
734	}
735	/* eslint-enable max-statements-per-line */
736
737	mg = (1.0 - c) * g;
738
739	return [
740		(c * pure[0] + mg) * 255,
741		(c * pure[1] + mg) * 255,
742		(c * pure[2] + mg) * 255
743	];
744};
745
746convert.hcg.hsv = function (hcg) {
747	const c = hcg[1] / 100;
748	const g = hcg[2] / 100;
749
750	const v = c + g * (1.0 - c);
751	let f = 0;
752
753	if (v > 0.0) {
754		f = c / v;
755	}
756
757	return [hcg[0], f * 100, v * 100];
758};
759
760convert.hcg.hsl = function (hcg) {
761	const c = hcg[1] / 100;
762	const g = hcg[2] / 100;
763
764	const l = g * (1.0 - c) + 0.5 * c;
765	let s = 0;
766
767	if (l > 0.0 && l < 0.5) {
768		s = c / (2 * l);
769	} else
770	if (l >= 0.5 && l < 1.0) {
771		s = c / (2 * (1 - l));
772	}
773
774	return [hcg[0], s * 100, l * 100];
775};
776
777convert.hcg.hwb = function (hcg) {
778	const c = hcg[1] / 100;
779	const g = hcg[2] / 100;
780	const v = c + g * (1.0 - c);
781	return [hcg[0], (v - c) * 100, (1 - v) * 100];
782};
783
784convert.hwb.hcg = function (hwb) {
785	const w = hwb[1] / 100;
786	const b = hwb[2] / 100;
787	const v = 1 - b;
788	const c = v - w;
789	let g = 0;
790
791	if (c < 1) {
792		g = (v - c) / (1 - c);
793	}
794
795	return [hwb[0], c * 100, g * 100];
796};
797
798convert.apple.rgb = function (apple) {
799	return [(apple[0] / 65535) * 255, (apple[1] / 65535) * 255, (apple[2] / 65535) * 255];
800};
801
802convert.rgb.apple = function (rgb) {
803	return [(rgb[0] / 255) * 65535, (rgb[1] / 255) * 65535, (rgb[2] / 255) * 65535];
804};
805
806convert.gray.rgb = function (args) {
807	return [args[0] / 100 * 255, args[0] / 100 * 255, args[0] / 100 * 255];
808};
809
810convert.gray.hsl = function (args) {
811	return [0, 0, args[0]];
812};
813
814convert.gray.hsv = convert.gray.hsl;
815
816convert.gray.hwb = function (gray) {
817	return [0, 100, gray[0]];
818};
819
820convert.gray.cmyk = function (gray) {
821	return [0, 0, 0, gray[0]];
822};
823
824convert.gray.lab = function (gray) {
825	return [gray[0], 0, 0];
826};
827
828convert.gray.hex = function (gray) {
829	const val = Math.round(gray[0] / 100 * 255) & 0xFF;
830	const integer = (val << 16) + (val << 8) + val;
831
832	const string = integer.toString(16).toUpperCase();
833	return '000000'.substring(string.length) + string;
834};
835
836convert.rgb.gray = function (rgb) {
837	const val = (rgb[0] + rgb[1] + rgb[2]) / 3;
838	return [val / 255 * 100];
839};
840