Initial Commit

node_modules/color-space/ycbcr.js

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+/**
+ * https://en.wikipedia.org/?title=YCbCr
+ *
+ * YCbCr is a digital form of YPbPr conversion
+ * Thence limits are [16...235], according to the ITU-R BT.709 or ITU-R BT.601
+ *
+ * @module  color-space/ycbcr
+ */
+import rgb from './rgb.js'
+import ypbpr from './ypbpr.js'
+
+var ycbcr = {
+	name: 'ycbcr',
+	min: [16, 16, 16],
+	max: [235, 240, 240],
+	channel: ['Y', 'Cb', 'Cr'],
+	alias: ['YCbCr', 'YCC'],
+	/**
+	 * From digital to analog form.
+	 * Scale to min/max ranges
+	 */
+	ypbpr: function (ycbcr) {
+		var y = ycbcr[0], cb = ycbcr[1], cr = ycbcr[2];
+
+		return [
+			(y - 16) / 219,
+			(cb - 128) / 224,
+			(cr - 128) / 224
+		];
+	}
+};
+
+
+/**
+ * From analog to digital form.
+ * Simple scale to min/max ranges
+ *
+ * @return {Array<number>} Resulting digitized form
+ */
+ypbpr.ycbcr = function (ypbpr) {
+	var y = ypbpr[0], pb = ypbpr[1], pr = ypbpr[2];
+
+	return [
+		16 + 219 * y,
+		128 + 224 * pb,
+		128 + 224 * pr
+	];
+}
+
+
+/**
+ * YCbCr to RGB
+ * transform through analog form
+ *
+ * @param {Array<number>} arr RGB values
+ * @param {number} kb
+ * @param {number} kr
+ * @return {Array<number>} YCbCr values
+ */
+ycbcr.rgb = function (arr, kb, kr) {
+	return ypbpr.rgb(ycbcr.ypbpr(arr), kb, kr);
+};
+
+
+/**
+ * RGB to YCbCr
+ * transform through analog form
+ *
+ * @param {Array<number>} arr YCbCr values
+ * @param {number} kb
+ * @param {number} kr
+ * @return {Array<number>} RGB values
+ */
+rgb.ycbcr = function (arr, kb, kr) {
+	return ypbpr.ycbcr(rgb.ypbpr(arr, kb, kr));
+};
+
+
+export default (ycbcr);