color-space - npm Package Compare versions

Comparing version 1.7.0 to 1.8.0

index.js

@@ -24,2 +24,3 @@ /**
 	ypbpr: require('./ypbpr'),
+	ycbcr: require('./ycbcr'),
 	lab: require('./lab'),
@@ -26,0 +27,0 @@ labh: require('./labh'),

package.json

 {
   "name": "color-space",
   "description": "Color space conversions and data",
-  "version": "1.7.0",
+  "version": "1.8.0",
   "author": "Deema Yvanow <[e-mail]>",
@@ -6,0 +6,0 @@ "keywords": [

readme.md

@@ -62,6 +62,8 @@ # Color-space [![Build Status](https://travis-ci.org/dfcreative/color-space.svg?branch=master)](https://travis-ci.org/dfcreative/color-space) [![Code Climate](https://codeclimate.com/github/dfcreative/color-space/badges/gpa.svg)](https://codeclimate.com/github/dfcreative/color-space) [![stable](http://badges.github.io/stability-badges/dist/stable.svg)](http://github.com/badges/stability-badges)
 * [x] [YIQ](https://en.wikipedia.org/?title=YIQ)
-* [x] [YDbDr](https://en.wikipedia.org/wiki/YDbDr)
-* [x] [YPbPr](https://en.wikipedia.org/wiki/YPbPr)
-* [ ] [YCbCr](https://en.wikipedia.org/wiki/YCbCr)
-* [ ] [YCgCo](https://en.wikipedia.org/wiki/YCgCo)
+* [ ] [YC<sub>g</sub>C<sub>o</sub>](https://en.wikipedia.org/wiki/YCgCo)
+* [x] [YD<sub>b</sub>D<sub>r</sub>](https://en.wikipedia.org/wiki/YDbDr)
+* [x] [YP<sub>b</sub>P<sub>r</sub>](https://en.wikipedia.org/wiki/YPbPr)
+* [x] [YC<sub>b</sub>C<sub>r</sub>](https://en.wikipedia.org/wiki/YCbCr)
+* [ ] [Y<sub>c</sub>C<sub>bc</sub>C<sub>rc</sub>](https://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.2020_conversion)
+* [ ] [JPEG](https://en.wikipedia.org/wiki/YCbCr#JPEG_conversion)
 * [ ] [XvYCC](https://en.wikipedia.org/wiki/XvYCC)
@@ -68,0 +70,0 @@ * [ ] [UVW](https://en.wikipedia.org/wiki/CIE_1964_color_space)

ycbcr.js

 /**
  * 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
@@ -8,9 +11,10 @@ */
 var rgb = require('./rgb');
+var ypbpr = require('./ypbpr');
 
 var ycbcr = module.exports = {
 	name: 'ycbcr',
-	min: [0,-0.5,-0.5],
-	max: [1, 0.5, 0.5],
+	min: [16, 16, 16],
+	max: [235, 240, 240],
 	channel: ['Y','Cb','Cr'],
-	alias: ['YCbCr']
+	alias: ['YCbCr', 'YCC']
 };
@@ -20,10 +24,43 @@
 /**
- * UVW to RGB
+ * From analog to digital form.
+ * Simple scale to min/max ranges
  *
+ * @return {Array} 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
+	];
+}
+
+
+/**
+ * From digital to analog form.
+ * Scale to min/max ranges
+ */
+ycbcr.ypbpr = function (ycbcr) {
+	var y = ycbcr[0], cb = ycbcr[1], cr = ycbcr[2];
+
+	return [
+		(y - 16) / 219,
+		(cb - 128) / 224,
+		(cr - 128) / 224
+	];
+}
+
+
+/**
+ * YCbCr to RGB
+ * transform through analog form
+ *
  * @param {Array} ycbcr RGB values
  *
- * @return {Array} UVW values
+ * @return {Array} YCbCr values
  */
-ycbcr.rgb = function(ycbcr) {
-
+ycbcr.rgb = function (arr, kb, kr) {
+	return ypbpr.rgb(ycbcr.ypbpr(arr), kb, kr);
 };
@@ -33,10 +70,11 @@
 /**
- * RGB to UVW
+ * RGB to YCbCr
+ * transform through analog form
  *
- * @param {Array} ycbcr UVW values
+ * @param {Array} ycbcr YCbCr values
  *
  * @return {Array} RGB values
  */
-rgb.ycbcr = function(rgb) {
-
+rgb.ycbcr = function(arr, kr, kb) {
+	return ypbpr.ycbcr(rgb.ypbpr(arr, kb, kr));
 };

ypbpr.js

 /**
  * https://en.wikipedia.org/?title=YPbPr
  *
- * HDTV conversion is used
+ * YPbPr is analog form of YCbCr
+ * hence limits are [0..1]
  *
+ * Default conversion is ITU-R BT.709
+ *
  * @module  color-space/ypbpr
@@ -13,4 +16,4 @@ */
 	name: 'ypbpr',
-	min: [0,-1.333,-1.333],
-	max: [1, 1.333, 1.333],
+	min: [0,-0.5,-0.5],
+	max: [1, 0.5, 0.5],
 	channel: ['Y','Pb','Pr'],
@@ -28,14 +31,14 @@ alias: ['YPbPr', 'Y/PB/PR', 'YPRPB', 'PRPBY', 'PBPRY', 'Y/Pb/Pr', 'YPrPb', 'PrPbY', 'PbPrY', 'Y/R-Y/B-Y', 'Y(R-Y)(B-Y)', 'R-Y', 'B-Y']
  */
-ypbpr.rgb = function(ypbpr) {
+ypbpr.rgb = function(ypbpr, kb, kr) {
 	var y = ypbpr[0], pb = ypbpr[1], pr = ypbpr[2];
 
-	var r = pr + y;
-	var b = pb + y;
-	var g = (y - 0.2126*r - 0.0722*b) / 0.7152;
+	//default conversion is ITU-R BT.709
+	kb = kb || 0.0722;
+	kr = kr || 0.2126;
 
-	return [
-		r * 255,
-		g * 255,
-		b * 255
-	];
+	var r = y + 2 * pr * (1 - kr);
+	var b = y + 2 * pb * (1 - kb);
+	var g = (y - kr * r - kb * b) / (1 - kr - kb);
+
+	return [r*255,g*255,b*255];
 };
@@ -51,12 +54,14 @@
  */
-rgb.ypbpr = function(rgb) {
+rgb.ypbpr = function(rgb, kb, kr) {
 	var r = rgb[0]/255, g = rgb[1]/255, b = rgb[2]/255;
 
-	var y = 0.2126 * r + 0.7152 * g + 0.0722 * b;
+	//ITU-R BT.709
+	kb = kb || 0.0722;
+	kr = kr || 0.2126;
 
-	return [
-		y,
-		b - y,
-		r - y
-	];
+	var y = kr*r + (1 - kr - kb)*g + kb*b;
+	var pb = 0.5 * (b - y) / (1 - kb);
+	var pr = 0.5 * (r - y) / (1 - kr);
+
+	return [y, pb, pr];
 };

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Improved metrics

Total package byte prevSize

92079

increased by2.86%

Number of package files

33

increased by6.45%

Lines of code

2900

increased by3.09%

Number of lines in readme file

101

increased by2.02%

No dependency changes