86 lines
1.7 KiB
JavaScript
86 lines
1.7 KiB
JavaScript
/**
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* https://en.wikipedia.org/wiki/XvYCC
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*
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* Sony xvYCC is extended YCbCr
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*
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* It uses same transformation as
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* SD: ITU-R BT.601
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* HD: ITU-R BT.709
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*
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* But have extended mins/maxes, which (may) result in negative rgb values
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*
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* https://web.archive.org/web/20130524104850/http://www.sony.net/SonyInfo/technology/technology/theme/xvycc_01.html
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*
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* //TODO: look for a spec (120$) - there are xvYCC ←→ XYZ conversion formulas
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*
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* @module color-space/xvycc
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*/
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import rgb from './rgb.js';
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import ypbpr from './ypbpr.js';
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var xvycc = {
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name: 'xvycc',
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min: [0, 0, 0],
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max: [255, 255, 255],
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channel: ['Y', 'Cb', 'Cr'],
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alias: ['xvYCC'],
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/**
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* From digital to analog form.
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* Scale to min/max ranges
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*/
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ypbpr: function (xvycc) {
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var y = xvycc[0], cb = xvycc[1], cr = xvycc[2];
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return [
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(y - 16) / 219,
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(cb - 128) / 224,
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(cr - 128) / 224
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];
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},
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/**
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* xvYCC to RGB
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* transform through analog form
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*
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* @param {Array<number>} arr RGB values
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* @param {number} kb
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* @param {number} kr
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* @return {Array<number>} xvYCC values
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*/
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rgb: function (arr, kb, kr) {
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return ypbpr.rgb(xvycc.ypbpr(arr), kb, kr);
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}
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};
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export default (xvycc);
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/**
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* From analog to digital form.
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* Simple scale to min/max ranges
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*
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* @return {Array<number>} Resulting digitized form
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*/
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ypbpr.xvycc = function (ypbpr) {
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var y = ypbpr[0], pb = ypbpr[1], pr = ypbpr[2];
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return [
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16 + 219 * y,
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128 + 224 * pb,
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128 + 224 * pr
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];
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}
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/**
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* RGB to xvYCC
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* transform through analog form
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*
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* @param {Array<number>} arr xvYCC values
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* @param {number} kb
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* @param {number} kr
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* @return {Array<number>} RGB values
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*/
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rgb.xvycc = function (arr, kb, kr) {
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return ypbpr.xvycc(rgb.ypbpr(arr, kb, kr));
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};
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