X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=white_balance_effect.cpp;h=d022984b71676a2abb5d38a2c1a1014a6860216f;hp=4c24cd210c9d098c8b549f5cd85b7e70cc12b698;hb=6f0ec2d7c127b139ed7cc42348bf518236e12dbd;hpb=cfe0bc4fa1e2a56eeb12c33e596f79c1292292c8 diff --git a/white_balance_effect.cpp b/white_balance_effect.cpp index 4c24cd2..d022984 100644 --- a/white_balance_effect.cpp +++ b/white_balance_effect.cpp @@ -1,42 +1,44 @@ #include #include +#include + #include "white_balance_effect.h" #include "util.h" #include "opengl.h" +using namespace Eigen; + namespace { // Temperature is in Kelvin. Formula from http://en.wikipedia.org/wiki/Planckian_locus#Approximation . -void convert_color_temperature_to_xyz(float T, float *x, float *y, float *z) +Vector3d convert_color_temperature_to_xyz(float T) { double invT = 1.0 / T; - double xc, yc; + double x, y; assert(T >= 1000.0f); assert(T <= 15000.0f); if (T <= 4000.0f) { - xc = ((-0.2661239e9 * invT - 0.2343580e6) * invT + 0.8776956e3) * invT + 0.179910; + x = ((-0.2661239e9 * invT - 0.2343580e6) * invT + 0.8776956e3) * invT + 0.179910; } else { - xc = ((-3.0258469e9 * invT + 2.1070379e6) * invT + 0.2226347e3) * invT + 0.240390; + x = ((-3.0258469e9 * invT + 2.1070379e6) * invT + 0.2226347e3) * invT + 0.240390; } if (T <= 2222.0f) { - yc = ((-1.1063814 * xc - 1.34811020) * xc + 2.18555832) * xc - 0.20219683; + y = ((-1.1063814 * x - 1.34811020) * x + 2.18555832) * x - 0.20219683; } else if (T <= 4000.0f) { - yc = ((-0.9549476 * xc - 1.37418593) * xc + 2.09137015) * xc - 0.16748867; + y = ((-0.9549476 * x - 1.37418593) * x + 2.09137015) * x - 0.16748867; } else { - yc = (( 3.0817580 * xc - 5.87338670) * xc + 3.75112997) * xc - 0.37001483; + y = (( 3.0817580 * x - 5.87338670) * x + 3.75112997) * x - 0.37001483; } - *x = xc; - *y = yc; - *z = 1.0 - xc - yc; + return Vector3d(x, y, 1.0 - x - y); } // Assuming sRGB primaries, from Wikipedia. -static const Matrix3x3 rgb_to_xyz_matrix = { +double rgb_to_xyz_matrix[9] = { 0.4124, 0.2126, 0.0193, 0.3576, 0.7152, 0.1192, 0.1805, 0.0722, 0.9505, @@ -54,7 +56,7 @@ static const Matrix3x3 rgb_to_xyz_matrix = { * in the first place) assumes the D65 illuminant, and so the D65 illuminant * also gives R=G=B in sRGB. */ -static const Matrix3x3 xyz_to_lms_matrix = { +const double xyz_to_lms_matrix[9] = { 0.4002, -0.2263, 0.0, 0.7076, 1.1653, 0.0, -0.0808, 0.0457, 0.9182, @@ -70,17 +72,18 @@ static const Matrix3x3 xyz_to_lms_matrix = { * for the reference color. Since L'=M'=S' and the Y row of the LMS-to-XYZ matrix * sums to unity, we know that Y'=L', and it's easy to find the fL that sets Y'=Y. */ -static void compute_lms_scaling_factors(float x, float y, float z, float *scale_l, float *scale_m, float *scale_s) +Vector3d compute_lms_scaling_factors(const Vector3d &xyz) { - Matrix3x3 xyz_to_rgb_matrix; - invert_3x3_matrix(rgb_to_xyz_matrix, xyz_to_rgb_matrix); + Vector3d lms = Map(xyz_to_lms_matrix) * xyz; + double l = lms[0]; + double m = lms[1]; + double s = lms[2]; - float l, m, s; - multiply_3x3_matrix_float3(xyz_to_rgb_matrix, x, y, z, &l, &m, &s); + double scale_l = xyz[1] / l; + double scale_m = scale_l * (l / m); + double scale_s = scale_l * (l / s); - *scale_l = y / l; - *scale_m = *scale_l * (l / m); - *scale_s = *scale_l * (l / s); + return Vector3d(scale_l, scale_m, scale_s); } } // namespace @@ -100,14 +103,9 @@ std::string WhiteBalanceEffect::output_fragment_shader() void WhiteBalanceEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num) { - float x, y, z; - multiply_3x3_matrix_float3(rgb_to_xyz_matrix, neutral_color.r, neutral_color.g, neutral_color.b, &x, &y, &z); - - float l, m, s; - multiply_3x3_matrix_float3(xyz_to_lms_matrix, x, y, z, &l, &m, &s); - - float l_scale, m_scale, s_scale; - compute_lms_scaling_factors(x, y, z, &l_scale, &m_scale, &s_scale); + Vector3d rgb(neutral_color.r, neutral_color.g, neutral_color.b); + Vector3d xyz = Map(rgb_to_xyz_matrix) * rgb; + Vector3d lms_scale = compute_lms_scaling_factors(xyz); /* * Now apply the color balance. Simply put, we find the chromacity point @@ -117,37 +115,26 @@ void WhiteBalanceEffect::set_gl_state(GLuint glsl_program_num, const std::string * since the D65 illuminant does not exactly match the results of T=6500K); * we normalize so that T=6500K really is a no-op. */ - float white_x, white_y, white_z, l_scale_white, m_scale_white, s_scale_white; - convert_color_temperature_to_xyz(output_color_temperature, &white_x, &white_y, &white_z); - compute_lms_scaling_factors(white_x, white_y, white_z, &l_scale_white, &m_scale_white, &s_scale_white); - - float ref_x, ref_y, ref_z, l_scale_ref, m_scale_ref, s_scale_ref; - convert_color_temperature_to_xyz(6500.0f, &ref_x, &ref_y, &ref_z); - compute_lms_scaling_factors(ref_x, ref_y, ref_z, &l_scale_ref, &m_scale_ref, &s_scale_ref); - - l_scale *= l_scale_ref / l_scale_white; - m_scale *= m_scale_ref / m_scale_white; - s_scale *= s_scale_ref / s_scale_white; + Vector3d white_xyz = convert_color_temperature_to_xyz(output_color_temperature); + Vector3d lms_scale_white = compute_lms_scaling_factors(white_xyz); + + Vector3d ref_xyz = convert_color_temperature_to_xyz(6500.0f); + Vector3d lms_scale_ref = compute_lms_scaling_factors(ref_xyz); + + lms_scale[0] *= lms_scale_ref[0] / lms_scale_white[0]; + lms_scale[1] *= lms_scale_ref[1] / lms_scale_white[1]; + lms_scale[2] *= lms_scale_ref[2] / lms_scale_white[2]; /* * Concatenate all the different linear operations into a single 3x3 matrix. * Note that since we postmultiply our vectors, the order of the matrices * has to be the opposite of the execution order. */ - Matrix3x3 lms_to_xyz_matrix, xyz_to_rgb_matrix; - invert_3x3_matrix(xyz_to_lms_matrix, lms_to_xyz_matrix); - invert_3x3_matrix(rgb_to_xyz_matrix, xyz_to_rgb_matrix); - - Matrix3x3 temp, temp2, corr_matrix; - Matrix3x3 lms_scale_matrix = { - l_scale, 0.0f, 0.0f, - 0.0f, m_scale, 0.0f, - 0.0f, 0.0f, s_scale, - }; - multiply_3x3_matrices(xyz_to_rgb_matrix, lms_to_xyz_matrix, temp); - multiply_3x3_matrices(temp, lms_scale_matrix, temp2); - multiply_3x3_matrices(temp2, xyz_to_lms_matrix, temp); - multiply_3x3_matrices(temp, rgb_to_xyz_matrix, corr_matrix); - + Matrix3d corr_matrix = + Map(rgb_to_xyz_matrix).inverse() * + Map(xyz_to_lms_matrix).inverse() * + lms_scale.asDiagonal() * + Map(xyz_to_lms_matrix) * + Map(rgb_to_xyz_matrix); set_uniform_mat3(glsl_program_num, prefix, "correction_matrix", corr_matrix); }