44 lines
994 B
JavaScript
44 lines
994 B
JavaScript
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/*
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Convert Rec. 2020 values to CIE XYZ D65
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References:
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* https://drafts.csswg.org/css-color/#color-conversion-code
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* http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
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* https://www.itu.int/rec/R-REC-BT.2020/en
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*/
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const α = 1.09929682680944;
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const β = 0.018053968510807;
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const linearize = v => {
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let abs = Math.abs(v);
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if (abs < β * 4.5) {
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return v / 4.5;
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}
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return (Math.sign(v) || 1) * Math.pow((abs + α - 1) / α, 1 / 0.45);
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};
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const convertRec2020ToXyz65 = rec2020 => {
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let r = linearize(rec2020.r);
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let g = linearize(rec2020.g);
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let b = linearize(rec2020.b);
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let res = {
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mode: 'xyz65',
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x:
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0.6369580483012911 * r +
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0.1446169035862083 * g +
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0.1688809751641721 * b,
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y:
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0.262700212011267 * r +
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0.6779980715188708 * g +
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0.059301716469862 * b,
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z: 0 * r + 0.0280726930490874 * g + 1.0609850577107909 * b
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};
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if (rec2020.alpha !== undefined) {
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res.alpha = rec2020.alpha;
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}
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return res;
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};
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export default convertRec2020ToXyz65;
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