X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=colorspace_conversion_effect.cpp;h=0e2425593acfe18da75824b56beb2748672c5c27;hp=baced38fb9b6c03e6d1ca94d4b0a38a36d3c2d34;hb=b5a446a44ee1f0379e8427f86f5dfa0d40bc0e60;hpb=57061265db1842d85c96bc678297d13b30661ab8

diff --git a/colorspace_conversion_effect.cpp b/colorspace_conversion_effect.cpp
index baced38..0e24255 100644
--- a/colorspace_conversion_effect.cpp
+++ b/colorspace_conversion_effect.cpp
@@ -1,10 +1,10 @@
 #include <assert.h>
-
+#include <Eigen/Core>
 #include <Eigen/LU>
 
 #include "colorspace_conversion_effect.h"
-#include "util.h"
 #include "d65.h"
+#include "util.h"
 
 using namespace Eigen;
 
@@ -57,14 +57,6 @@ Matrix3d get_xyz_matrix(Colorspace space)
 	double z_G = 1.0 - x_G - y_G;
 	double z_B = 1.0 - x_B - y_B;
 
-	// Find the XYZ coordinates of D65 (white point for both Rec. 601 and 709),
-	// normalized so that Y=1.
-	Vector3d d65_XYZ(
-		d65_x / d65_y,
-		1.0,
-		d65_z / d65_y
-	);
-
 	// We have, for each primary (example is with red):
 	//
 	//   X_R / (X_R + Y_R + Z_R) = x_R
@@ -73,8 +65,8 @@ Matrix3d get_xyz_matrix(Colorspace space)
 	//
 	// Some algebraic fiddling yields (unsurprisingly):
 	//
-	//   X_R = (x_R / y_R) Y_R
-	//   Z_R = (z_R / y_R) Y_R
+	//   X_R = (x_R / y_R) Y_R   (so define k1 = x_R / y_R)
+	//   Z_R = (z_R / y_R) Y_R   (so define k4 = z_R / y_R)
 	//
 	// We also know that since RGB=(1,1,1) should give us the
 	// D65 illuminant, we must have
@@ -83,8 +75,8 @@ Matrix3d get_xyz_matrix(Colorspace space)
 	//   Y_R + Y_G + Y_B = D65_Y
 	//   Z_R + Z_G + Z_B = D65_Z
 	//
-	// But since we already know how to express Y and Z by
-	// some constant multiple of X, this reduces to
+	// But since we already know how to express X and Z by
+	// some constant multiple of Y, this reduces to
 	//
 	//   k1 Y_R + k2 Y_G + k3 Y_B = D65_X
 	//      Y_R +    Y_G +    Y_B = D65_Y
@@ -105,6 +97,7 @@ Matrix3d get_xyz_matrix(Colorspace space)
 	temp(2,1) = z_G / y_G;
 	temp(2,2) = z_B / y_B;
 
+	Vector3d d65_XYZ(d65_X, d65_Y, d65_Z);
 	Vector3d Y_RGB = temp.inverse() * d65_XYZ;
 
 	// Now convert xyY -> XYZ.