Calculate the RGB-to-XYZ matrix ourselves instead of using a “magic” one from Wikipedia.

[movit] / white_balance_effect.cpp

diff --git a/white_balance_effect.cpp b/white_balance_effect.cpp
index 1583922461053dd1c793eaa51f93b28275b1cab5..2c99ca85c0b791379bd9e564ce2770df467e4664 100644 (file)
--- a/white_balance_effect.cpp
+++ b/white_balance_effect.cpp
@@ -3,7 +3,9 @@
 #include <GL/glew.h>
 #include <assert.h>
 
+#include "colorspace_conversion_effect.h"
 #include "d65.h"
+#include "effect_util.h"
 #include "util.h"
 #include "white_balance_effect.h"
 
@@ -21,7 +23,7 @@ Vector3d convert_color_temperature_to_xyz(float T)
        assert(T <= 15000.0f);
 
        if (T <= 4000.0f) {
-               x = ((-0.2661239e9 * invT - 0.2343580e6) * invT + 0.8776956e3) * invT + 0.179910;
+               x = ((-0.2661239e9 * invT - 0.2343589e6) * invT + 0.8776956e3) * invT + 0.179910;
        } else {
                x = ((-3.0258469e9 * invT + 2.1070379e6) * invT + 0.2226347e3) * invT + 0.240390;
        }
@@ -37,13 +39,6 @@ Vector3d convert_color_temperature_to_xyz(float T)
        return Vector3d(x, y, 1.0 - x - y);
 }
 
-// Assuming sRGB primaries, from Wikipedia.
-const double rgb_to_xyz_matrix[9] = {
-       0.4124, 0.2126, 0.0193, 
-       0.3576, 0.7152, 0.1192,
-       0.1805, 0.0722, 0.9505,
-};
-
 /*
  * There are several different perceptual color spaces with different intended
  * uses; for instance, CIECAM02 uses one space (CAT02) for purposes of computing
@@ -115,8 +110,9 @@ std::string WhiteBalanceEffect::output_fragment_shader()
 
 void WhiteBalanceEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
 {
+       Matrix3d rgb_to_xyz_matrix = ColorspaceConversionEffect::get_xyz_matrix(COLORSPACE_sRGB);
        Vector3d rgb(neutral_color.r, neutral_color.g, neutral_color.b);
-       Vector3d xyz = Map<const Matrix3d>(rgb_to_xyz_matrix) * rgb;
+       Vector3d xyz = rgb_to_xyz_matrix * rgb;
        Vector3d lms_scale = compute_lms_scaling_factors(xyz);
 
        /*
@@ -143,10 +139,10 @@ void WhiteBalanceEffect::set_gl_state(GLuint glsl_program_num, const std::string
         * has to be the opposite of the execution order.
         */
        Matrix3d corr_matrix =
-               Map<const Matrix3d>(rgb_to_xyz_matrix).inverse() *
+               rgb_to_xyz_matrix.inverse() *
                Map<const Matrix3d>(xyz_to_lms_matrix).inverse() *
                lms_scale.asDiagonal() *
                Map<const Matrix3d>(xyz_to_lms_matrix) *
-               Map<const Matrix3d>(rgb_to_xyz_matrix);
+               rgb_to_xyz_matrix;
        set_uniform_mat3(glsl_program_num, prefix, "correction_matrix", corr_matrix);
 }