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//
// Color Spaces
//
// $Id: Color.C,v 4.0.2.1.2.1 1999/07/20 16:15:49 geert Exp $
//
// Copyright (C) 1996-1999 Department of Computer Science, K.U.Leuven, Belgium
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
#include <math.h>
#include "waili/Color.h"
#include "waili/Util.h"
const char *ColorSpace::rcsid = "$Id: Color.C,v 4.0.2.1.2.1 1999/07/20 16:15:49 geert Exp $";
static f32 DefaultPrimChroma[6] = {
0.6400, 0.3300,
0.3000, 0.6000,
0.1500, 0.0600
};
static f32 DefaultWhitePoint[2] = {
0.3127, 0.3290
};
ColorSpace::ColorSpace(void)
{
SetPrimChroma(DefaultPrimChroma, 0);
SetWhitePoint(DefaultWhitePoint, 1);
}
void ColorSpace::SetPrimChroma(const f32 chroma[6], int immediate)
{
PrimChroma[0].x = chroma[0];
PrimChroma[0].y = chroma[1];
PrimChroma[0].z = 1.0-PrimChroma[0].x-PrimChroma[0].y;
PrimChroma[1].x = chroma[2];
PrimChroma[1].y = chroma[3];
PrimChroma[1].z = 1.0-PrimChroma[1].x-PrimChroma[1].y;
PrimChroma[2].x = chroma[4];
PrimChroma[2].y = chroma[5];
PrimChroma[2].z = 1.0-PrimChroma[2].x-PrimChroma[2].y;
if (immediate)
CalcConvMat();
}
void ColorSpace::GetPrimChroma(f32 chroma[6]) const
{
chroma[0] = PrimChroma[0].x;
chroma[1] = PrimChroma[0].y;
chroma[2] = PrimChroma[1].x;
chroma[3] = PrimChroma[1].y;
chroma[4] = PrimChroma[2].x;
chroma[5] = PrimChroma[2].y;
}
void ColorSpace::SetWhitePoint(const f32 wp[2], int immediate)
{
WhitePoint.x = wp[0]/wp[1];
WhitePoint.y = 1.0;
WhitePoint.z = (1.0-wp[0]-wp[1])/wp[1];
if (immediate)
CalcConvMat();
}
void ColorSpace::GetWhitePoint(f32 wp[2]) const
{
wp[1] = 1.0/(1.0+WhitePoint.x+WhitePoint.z);
wp[0] = WhitePoint.x*wp[1];
}
void ColorSpace::CalcConvMat(void)
{
f32 mat[3][3], white[3], scale[3], c;
int ind[3], t;
u_int i, j, k;
// Normalized white point
white[0] = WhitePoint.x;
white[1] = WhitePoint.y;
white[2] = WhitePoint.z;
for (i = 0; i < 3; i++) {
mat[0][i] = PrimChroma[i].x;
mat[1][i] = PrimChroma[i].y;
mat[2][i] = PrimChroma[i].z;
ind[i] = i;
}
// Gaussian elimination with partial pivoting
for (i = 0; i < 2; i++) {
for (j = i+1; j < 3; j++)
if (fabs(mat[ind[j]][i]) > fabs(mat[ind[i]][i])) {
t = ind[j];
ind[j] = ind[i];
ind[i] = t;
}
if (fabs(mat[ind[i]][i]) < EPS)
Die("%s: Matrix is singular\n", __FUNCTION__);
for (j = i+1; j < 3; j++) {
c = mat[ind[j]][i]/mat[ind[i]][i];
for (k = i+1; k < 3; k++)
mat[ind[j]][k] -= c*mat[ind[i]][k];
white[ind[j]] -= c*white[ind[i]];
}
}
if (fabs(mat[ind[2]][2]) < EPS)
Die("%s: Matrix is singular\n", __FUNCTION__);
// Back substitution to solve for scale
scale[ind[2]] = white[ind[2]]/mat[ind[2]][2];
scale[ind[1]] = (white[ind[1]]-(mat[ind[1]][2]*scale[ind[2]]))/
mat[ind[1]][1];
scale[ind[0]] = (white[ind[0]]-(mat[ind[0]][1]*scale[ind[1]])-
(mat[ind[0]][2]*scale[ind[2]]))/mat[ind[0]][0];
// Build matrix RGB->XYZ
for (i = 0; i < 3; i++) {
RGB2XYZ[0][i] = scale[i]*PrimChroma[i].x;
RGB2XYZ[1][i] = scale[i]*PrimChroma[i].y;
RGB2XYZ[2][i] = scale[i]*PrimChroma[i].z;
}
for (i = 0; i < 3; i++)
for (j = 0; j < 3; j++) {
mat[i][j] = RGB2XYZ[i][j];
XYZ2RGB[i][j] = i == j ? 1.0 : 0.0;
}
for (i = 0; i < 3; i++) {
for (j = i+1, k = i; j < 3; j++)
if (fabs(mat[j][i]) > fabs(mat[k][i]))
k = j;
// Check for singularity
if (fabs(mat[k][i]) < EPS)
Die("%s: Matrix is singular\n", __FUNCTION__);
// Pivot - switch rows k and i
if (k != i)
for (j = 0; j < 3; j++) {
c = mat[i][j];
mat[i][j] = mat[k][j];
mat[k][j] = c;
c = XYZ2RGB[i][j];
XYZ2RGB[i][j] = XYZ2RGB[k][j];
XYZ2RGB[k][j] = c;
}
// Normalize the row - make the diagonal 1
c = 1.0/mat[i][i];
for (j = 0; j < 3; j++) {
if (j != i)
mat[i][j] *= c;
else
mat[i][j] = 1.0;
XYZ2RGB[i][j] *= c;
}
// Zero the non-diagonal terms in this column
for (j = 0; j < 3; j++)
if (j != i) {
c = -mat[j][i];
for (k = 0; k < 3; k++) {
mat[j][k] += c*mat[i][k];
XYZ2RGB[j][k] += c*XYZ2RGB[i][k];
}
}
}
}
// Color Conversions
void ColorSpace::Convert(const Color_RGB &rgb, Color_XYZ &xyz) const
{
xyz.x = RGB2XYZ[0][0]*rgb.r+RGB2XYZ[0][1]*rgb.g+RGB2XYZ[0][2]*rgb.b;
xyz.y = RGB2XYZ[1][0]*rgb.r+RGB2XYZ[1][1]*rgb.g+RGB2XYZ[1][2]*rgb.b;
xyz.z = RGB2XYZ[2][0]*rgb.r+RGB2XYZ[2][1]*rgb.g+RGB2XYZ[2][2]*rgb.b;
}
void ColorSpace::Convert(const Color_XYZ &xyz, Color_RGB &rgb) const
{
rgb.r = XYZ2RGB[0][0]*xyz.x+XYZ2RGB[0][1]*xyz.y+XYZ2RGB[0][2]*xyz.z;
rgb.g = XYZ2RGB[1][0]*xyz.x+XYZ2RGB[1][1]*xyz.y+XYZ2RGB[1][2]*xyz.z;
rgb.b = XYZ2RGB[2][0]*xyz.x+XYZ2RGB[2][1]*xyz.y+XYZ2RGB[2][2]*xyz.z;
}
#define DARK_XYZ_VALUE (0.008856)
#define DARK_L_VALUE (7.999625)
#define DARK_AB_VALUE (0.206893)
void ColorSpace::Convert(const Color_XYZ &xyz, Color_LAB &lab) const
{
f32 x, y, z;
x = xyz.x/WhitePoint.x;
y = xyz.y;
z = xyz.z/WhitePoint.z;
if (y <= DARK_XYZ_VALUE) {
lab.l = 903.3*y;
y = pow(7.787*y+16.0/116.0, 1.0/3.0);
} else {
y = pow(y, 1.0/3.0);
lab.l = 116.0*y-16;
}
#if 0
if (x <= DARK_XYZ_VALUE)
x = 7.787*x+16.0/116.0;
if (z <= DARK_XYZ_VALUE)
z = 7.787*z+16.0/116.0;
#endif
x = pow(x, 1.0/3.0);
z = pow(z, 1.0/3.0);
lab.a = 500*(x-y);
lab.b = 200*(y-z);
}
void ColorSpace::Convert(const Color_LAB &lab, Color_XYZ &xyz) const
{
f32 x, y, z, t;
if (lab.l <= DARK_L_VALUE) {
y = lab.l/903.3;
t = pow(7.787*y+16.0/116.0, 1.0/3.0);
} else {
t = (lab.l+16.0)/116.0;
y = pow(t, 3.0);
}
x = pow(lab.a/500.0+t, 3.0);
z = pow(t-lab.b/200.0, 3.0);
#if 0
if (x <= DARK_AB_VALUE)
x = (x-16.0/116.0)/7.787;
if (y <= DARK_AB_VALUE)
y = (y-16.0/116.0)/7.787;
#endif
xyz.x = x*WhitePoint.x;
xyz.y = y;
xyz.z = z*WhitePoint.z;
}
// Color to Gray Conversions
void ColorSpace::Convert(const Color_RGB &rgb, Color_CIEY &y) const
{
y.y = RGB2XYZ[1][0]*rgb.r+RGB2XYZ[1][1]*rgb.g+RGB2XYZ[1][2]*rgb.b;
}
// Gray Conversions
void ColorSpace::Convert(const Color_CIEY &y, Color_CIEL &l)
{
if (y.y <= DARK_XYZ_VALUE)
l.l = 903.3*y.y;
else
l.l = 116.0*pow(y.y, 1.0/3.0)-16;
}
void ColorSpace::Convert(const Color_CIEL &l, Color_CIEY &y)
{
if (l.l <= DARK_L_VALUE)
y.y = l.l/903.3;
else
y.y = pow((l.l+16.0)/116.0, 3.0);
}
// Color Conversions (16 bit)
void ColorSpace::Convert(const Color_RGB16 &rgb, Color_YUVr16 &yuvr)
{
yuvr.yr = (rgb.r+2*rgb.g+rgb.b)>>2;
yuvr.ur = rgb.r-rgb.g;
yuvr.vr = rgb.b-rgb.g;
}
void ColorSpace::Convert(const Color_YUVr16 &yuvr, Color_RGB16 &rgb)
{
rgb.g = yuvr.yr-((yuvr.ur+yuvr.vr)>>2);
rgb.r = yuvr.ur+rgb.g;
rgb.b = yuvr.vr+rgb.g;
}
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