Initial Commit

node_modules/color-space/xvycc.js

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