culori/src/itp/convertItpToXyz65.js

A general-purpose color library for JavaScript

import { YW } from '../hdr/constants.js';
import { transferPqDecode } from '../hdr/transfer.js';

const toRel = c => Math.max(c / YW, 0);

const convertItpToXyz65 = ({ i, t, p, alpha }) => {
	if (i === undefined) i = 0;
	if (t === undefined) t = 0;
	if (p === undefined) p = 0;

	const l = transferPqDecode(
		i + 0.008609037037932761 * t + 0.11102962500302593 * p
	);
	const m = transferPqDecode(
		i - 0.00860903703793275 * t - 0.11102962500302599 * p
	);
	const s = transferPqDecode(
		i + 0.5600313357106791 * t - 0.32062717498731885 * p
	);

	const res = {
		mode: 'xyz65',
		x: toRel(
			2.0701522183894219 * l -
				1.3263473389671556 * m +
				0.2066510476294051 * s
		),
		y: toRel(
			0.3647385209748074 * l +
				0.680566024947227 * m -
				0.0453045459220346 * s
		),
		z: toRel(
			-0.049747207535812 * l -
				0.0492609666966138 * m +
				1.1880659249923042 * s
		)
	};

	if (alpha !== undefined) {
		res.alpha = alpha;
	}

	return res;
};

export default convertItpToXyz65;