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libglitter_get_colour_model_conversion_matrix_double.c
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libglitter_get_colour_model_conversion_matrix_double.c
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/* See LICENSE file for copyright and license details. */
#include "common.h"
#ifndef TEST
/**
* CIE XYZ-to-sRGB conversion matrix,
* in column-major order
*/
static const double srgb[3][3] = {
{ 3.240446254647737056586720427731, -0.969266606244679751469561779231, 0.055643503564352832235773149705},
{-1.537134761820080353089679192635, 1.876011959788370209167851498933, -0.204026179735960239147729566866},
{-0.498530193022728773666329971093, 0.041556042214430065351304932619, 1.057226567722703292062647051353}};
static void
eliminate(double m[3][4]) /* row-major order */
{
double t;
size_t i;
/* Set m[0][0] = 1 */ for (t = m[0][0], i = 0; i < 4; i++) m[0][i] /= t;
/* Set m[1][0] = 0 */ for (t = m[1][0], i = 0; i < 4; i++) m[1][i] -= t * m[0][i];
/* Set m[2][0] = 0 */ for (t = m[2][0], i = 0; i < 4; i++) m[2][i] -= t * m[0][i];
/* Set m[1][1] = 1 */ for (t = m[1][1], i = 1; i < 4; i++) m[1][i] /= t;
/* Set m[2][1] = 0 */ for (t = m[2][1], i = 1; i < 4; i++) m[2][i] -= t * m[1][i];
/* Set m[0][1] = 0 */ for (t = m[0][1], i = 1; i < 4; i++) m[0][i] -= t * m[1][i];
/* Set m[2][2] = 1 */ for (t = m[2][2], i = 2; i < 4; i++) m[2][i] /= t;
/* Set m[1][2] = 0 */ for (t = m[1][2], i = 2; i < 4; i++) m[1][i] -= t * m[2][i];
/* Set m[0][2] = 0 */ for (t = m[0][2], i = 2; i < 4; i++) m[0][i] -= t * m[2][i];
}
void
libglitter_get_colour_model_conversion_matrix_double(double matrix[3][3], double c1x, double c1y, double c2x, double c2y,
double c3x, double c3y, double white_x, double white_y, double white_Y,
int xyz, double *restrict c1Yp, double *restrict c2Yp, double *restrict c3Yp)
{
double mat[3][4];
double x1, x2, x3;
double y1, y2, y3;
double z1, z2, z3;
#define X(x, y) ((x) / (y))
#define Z(x, y) ((1 - (x)) / (y) - 1)
/* Get colour model in CIE XYZ (the matrix is in row-major order) */
mat[0][0] = x1 = X(c1x, c1y);
mat[0][1] = x2 = X(c2x, c2y);
mat[0][2] = x3 = X(c3x, c3y);
mat[0][3] = X(white_x, white_y) * white_Y;
mat[1][0] = 1;
mat[1][1] = 1;
mat[1][2] = 1;
mat[1][3] = white_Y;
mat[2][0] = z1 = Z(c1x, c1y);
mat[2][1] = z2 = Z(c2x, c2y);
mat[2][2] = z3 = Z(c3x, c3y);
mat[2][3] = Z(white_x, white_y) * white_Y;
eliminate(mat);
y1 = mat[0][3];
y2 = mat[1][3];
y3 = mat[2][3];
if (c1Yp)
*c1Yp = y1;
if (c2Yp)
*c2Yp = y2;
if (c3Yp)
*c3Yp = y3;
x1 *= y1;
x2 *= y2;
x3 *= y3;
z1 *= y1;
z2 *= y2;
z3 *= y3;
/* [x1, x2, x3; y1, y2, y3; z1, z2, z3] is
* the output RGB-to-CIE XYZ conversion matrix.
* If sRGB is desired, it is multiplied by the
* CIE XYZ-to-sRGB conversion matrix to get the
* output RGB-to-sRGB conversion matrix. The
* matrices are in column-major order. */
if (!xyz) {
matrix[0][0] = x1 * srgb[0][0] + x2 * srgb[0][1] + x3 * srgb[0][2];
matrix[1][0] = x1 * srgb[1][0] + x2 * srgb[1][1] + x3 * srgb[1][2];
matrix[2][0] = x1 * srgb[2][0] + x2 * srgb[2][1] + x3 * srgb[2][2];
matrix[0][1] = y1 * srgb[0][0] + y2 * srgb[0][1] + y3 * srgb[0][2];
matrix[1][1] = y1 * srgb[1][0] + y2 * srgb[1][1] + y3 * srgb[1][2];
matrix[2][1] = y1 * srgb[2][0] + y2 * srgb[2][1] + y3 * srgb[2][2];
matrix[0][2] = z1 * srgb[0][0] + z2 * srgb[0][1] + z3 * srgb[0][2];
matrix[1][2] = z1 * srgb[1][0] + z2 * srgb[1][1] + z3 * srgb[1][2];
matrix[2][2] = z1 * srgb[2][0] + z2 * srgb[2][1] + z3 * srgb[2][2];
} else {
matrix[0][0] = x1, matrix[1][0] = x2, matrix[2][0] = x3;
matrix[0][1] = y1, matrix[1][1] = y2, matrix[2][1] = y3;
matrix[0][2] = z1, matrix[1][2] = z2, matrix[2][2] = z3;
}
}
#else
#define TOLERANCE 0.0001
#define RX 0.412457445582367576708548995157
#define GX 0.357575865245515878143578447634
#define BX 0.180437247826399665973085006954
#define RY 0.212673370378408277403536885686
#define GY 0.715151730491031756287156895269
#define BY 0.072174899130559869164791564344
#define RZ 0.019333942761673460208893260415
#define GZ 0.119191955081838593666354597644
#define BZ 0.950302838552371742508739771438
#define Rx (RX / (RX + RY + RZ))
#define Gx (GX / (GX + GY + GZ))
#define Bx (BX / (BX + BY + BZ))
#define Ry (RY / (RX + RY + RZ))
#define Gy (GY / (GX + GY + GZ))
#define By (BY / (BX + BY + BZ))
#define Rz (RZ / (RX + RY + RZ))
#define Gz (GZ / (GX + GY + GZ))
#define Bz (BZ / (BX + BY + BZ))
static int
eq(double a, double b)
{
double r = a - b;
return (r < 0 ? -r : r) < TOLERANCE;
}
int
main(void)
{
double mat[3][3], c1Y, c2Y, c3Y;
#define RESET\
do {\
memset(mat, 0, sizeof(mat));\
c1Y = c2Y = c3Y = 0;\
} while (0)
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
1, &c1Y, &c2Y, &c3Y);
ASSERT(eq(c1Y, RY));
ASSERT(eq(c2Y, GY));
ASSERT(eq(c3Y, BY));
ASSERT(eq(mat[0][0], RX));
ASSERT(eq(mat[1][0], GX));
ASSERT(eq(mat[2][0], BX));
ASSERT(eq(mat[0][1], RY));
ASSERT(eq(mat[1][1], GY));
ASSERT(eq(mat[2][1], BY));
ASSERT(eq(mat[0][2], RZ));
ASSERT(eq(mat[1][2], GZ));
ASSERT(eq(mat[2][2], BZ));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
1, &c1Y, &c2Y, NULL);
ASSERT(eq(c1Y, RY));
ASSERT(eq(c2Y, GY));
ASSERT(eq(mat[0][0], RX));
ASSERT(eq(mat[1][0], GX));
ASSERT(eq(mat[2][0], BX));
ASSERT(eq(mat[0][1], RY));
ASSERT(eq(mat[1][1], GY));
ASSERT(eq(mat[2][1], BY));
ASSERT(eq(mat[0][2], RZ));
ASSERT(eq(mat[1][2], GZ));
ASSERT(eq(mat[2][2], BZ));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
1, &c1Y, NULL, &c3Y);
ASSERT(eq(c1Y, RY));
ASSERT(eq(c3Y, BY));
ASSERT(eq(mat[0][0], RX));
ASSERT(eq(mat[1][0], GX));
ASSERT(eq(mat[2][0], BX));
ASSERT(eq(mat[0][1], RY));
ASSERT(eq(mat[1][1], GY));
ASSERT(eq(mat[2][1], BY));
ASSERT(eq(mat[0][2], RZ));
ASSERT(eq(mat[1][2], GZ));
ASSERT(eq(mat[2][2], BZ));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
1, &c1Y, NULL, NULL);
ASSERT(eq(c1Y, RY));
ASSERT(eq(mat[0][0], RX));
ASSERT(eq(mat[1][0], GX));
ASSERT(eq(mat[2][0], BX));
ASSERT(eq(mat[0][1], RY));
ASSERT(eq(mat[1][1], GY));
ASSERT(eq(mat[2][1], BY));
ASSERT(eq(mat[0][2], RZ));
ASSERT(eq(mat[1][2], GZ));
ASSERT(eq(mat[2][2], BZ));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
1, NULL, &c2Y, &c3Y);
ASSERT(eq(c2Y, GY));
ASSERT(eq(c3Y, BY));
ASSERT(eq(mat[0][0], RX));
ASSERT(eq(mat[1][0], GX));
ASSERT(eq(mat[2][0], BX));
ASSERT(eq(mat[0][1], RY));
ASSERT(eq(mat[1][1], GY));
ASSERT(eq(mat[2][1], BY));
ASSERT(eq(mat[0][2], RZ));
ASSERT(eq(mat[1][2], GZ));
ASSERT(eq(mat[2][2], BZ));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
1, NULL, &c2Y, NULL);
ASSERT(eq(c2Y, GY));
ASSERT(eq(mat[0][0], RX));
ASSERT(eq(mat[1][0], GX));
ASSERT(eq(mat[2][0], BX));
ASSERT(eq(mat[0][1], RY));
ASSERT(eq(mat[1][1], GY));
ASSERT(eq(mat[2][1], BY));
ASSERT(eq(mat[0][2], RZ));
ASSERT(eq(mat[1][2], GZ));
ASSERT(eq(mat[2][2], BZ));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
1, NULL, NULL, &c3Y);
ASSERT(eq(c3Y, BY));
ASSERT(eq(mat[0][0], RX));
ASSERT(eq(mat[1][0], GX));
ASSERT(eq(mat[2][0], BX));
ASSERT(eq(mat[0][1], RY));
ASSERT(eq(mat[1][1], GY));
ASSERT(eq(mat[2][1], BY));
ASSERT(eq(mat[0][2], RZ));
ASSERT(eq(mat[1][2], GZ));
ASSERT(eq(mat[2][2], BZ));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
1, NULL, NULL, NULL);
ASSERT(eq(mat[0][0], RX));
ASSERT(eq(mat[1][0], GX));
ASSERT(eq(mat[2][0], BX));
ASSERT(eq(mat[0][1], RY));
ASSERT(eq(mat[1][1], GY));
ASSERT(eq(mat[2][1], BY));
ASSERT(eq(mat[0][2], RZ));
ASSERT(eq(mat[1][2], GZ));
ASSERT(eq(mat[2][2], BZ));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
0, &c1Y, &c2Y, &c3Y);
ASSERT(eq(c1Y, RY));
ASSERT(eq(c2Y, GY));
ASSERT(eq(c3Y, BY));
ASSERT(eq(mat[0][0], 1));
ASSERT(eq(mat[1][0], 0));
ASSERT(eq(mat[2][0], 0));
ASSERT(eq(mat[0][1], 0));
ASSERT(eq(mat[1][1], 1));
ASSERT(eq(mat[2][1], 0));
ASSERT(eq(mat[0][2], 0));
ASSERT(eq(mat[1][2], 0));
ASSERT(eq(mat[2][2], 1));
RESET;
libglitter_get_colour_model_conversion_matrix_double(mat, Rx, Ry, Gx, Gy, Bx, By,
LIBGLITTER_ILLUMINANT_D65,
0, NULL, NULL, NULL);
ASSERT(eq(mat[0][0], 1));
ASSERT(eq(mat[1][0], 0));
ASSERT(eq(mat[2][0], 0));
ASSERT(eq(mat[0][1], 0));
ASSERT(eq(mat[1][1], 1));
ASSERT(eq(mat[2][1], 0));
ASSERT(eq(mat[0][2], 0));
ASSERT(eq(mat[1][2], 0));
ASSERT(eq(mat[2][2], 1));
return 0;
}
#endif