matrixmaker tested

svgeesus · svgeesus · commit d6f8026fde2f · 2016-05-09T12:11:41.000-07:00
diff --git a/css-color/matrixmaker.html b/css-color/matrixmaker.html
@@ -1,3 +1,7 @@
+﻿<html>
+	<script src="math.js"></script>
+	<script>
+	
 // Make matrices for converting to and from an arbitrary RGB colorspace,
 // given the x,y chromaticities of red, green, blue and white.
 // To use these matrices, the RGB components are assumed be be 
@@ -7,10 +11,9 @@
 // Horribly hacky, non interactive utility. Edit the file to pick
 // another colorspace and read the results from the console :P
 
-<html>
-	<script src="math.js"></script>
-	<script>
+
 		// these are for ITU Rec BT.2020
+		/*
 		const xred=0.708 ;
 		const yred=0.292 ;
 		
@@ -19,6 +22,17 @@
 		
 		const xblue=0.131 ;
 		const yblue=0.046 ;
+		*/
+		
+		// AdobeRGB, for testing
+		const xred=0.640 ;
+		const yred=0.330 ;
+		
+		const xgreen=0.210 ;
+		const ygreen=0.710 ;
+		
+		const xblue=0.150 ;
+		const yblue=0.060 ;
 		
 		// D65
 		const xwhite=0.3127 ;
@@ -43,19 +57,40 @@
 		var ZBlue=(1 - xblue - yblue)/yblue;
 		
 		var white = math.matrix([XWhite, YWhite, ZWhite]);
-		var primaries = [
+		console.log(white.valueOf());
+		var primaries = math.matrix([
 			[XRed, XGreen, XBlue],
 			[YRed, YGreen, YBlue],
 			[ZRed, ZGreen, ZBlue]
-		];
+		]);
+		console.log(primaries.valueOf());
+		
+		var iprimaries = math.inv(primaries);
+		console.log(iprimaries.valueOf());
 		
 		// S is easier if it ends up as an array than a matrix
 		// but we use matrix math to calculate it
-		var S = math.multiply(math.inv(math.matrix(primaries)),white).value;
+		var S = math.multiply(math.inv(primaries),white).valueOf();
 		
-		var M = math.matrix([
-			[]
-		]);
+		var M = [
+			[S[0] * XRed, S[1] * XGreen, S[2] * XBlue],
+			[S[0] * YRed, S[1] * YGreen, S[2] * YBlue],
+			[S[0] * ZRed, S[1] * ZGreen, S[2] * ZBlue]
+		];
+		
+		console.log("RGB to XYZ");
+		console.log(M);
+		console.log("XYZ to RGB");
+		console.log(math.inv(math.matrix(M)).valueOf());
 		
+		// for code verification: with AdobeRGB primaries, correct result is
+		// M = 
+		//	[[0.5767309  0.1855540  0.1881852],
+ 		//	 [0.2973769  0.6273491  0.0752741],
+ 		//	 [0.0270343  0.0706872  0.9911085]];
+		// Minv =
+		//	[[2.0413690 -0.5649464 -0.3446944],
+		//	 [-0.9692660  1.8760108  0.0415560],
+ 		//	 [0.0134474 -0.1183897  1.0154096]];
 	</script>
 </html>
