80 lines
1.4 KiB
JavaScript
80 lines
1.4 KiB
JavaScript
/**
|
|
* 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);
|