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/*
Copyright (C) 2013 Carl Hetherington <cth@carlh.net>
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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "rgb_xyz.h"
#include "argb_frame.h"
#include "xyz_frame.h"
#include "gamma_lut.h"
using std::min;
using std::max;
using boost::shared_ptr;
using namespace libdcp;
/** Convert an openjpeg XYZ image to RGB.
* @param xyz_frame Frame in XYZ.
* @return RGB image.
*/
shared_ptr<ARGBFrame>
libdcp::xyz_to_rgb (shared_ptr<const XYZFrame> xyz_frame, shared_ptr<const GammaLUT> lut_in, shared_ptr<const GammaLUT> lut_out)
{
float const dci_coefficient = 48.0 / 52.37;
/* sRGB color matrix for XYZ -> RGB. This is the same as the one used by the Fraunhofer
EasyDCP player, I think.
*/
float const colour_matrix[3][3] = {
{ 3.24096989631653, -1.5373831987381, -0.498610764741898 },
{ -0.96924364566803, 1.87596750259399, 0.0415550582110882 },
{ 0.0556300804018974, -0.203976958990097, 1.05697154998779 }
};
int const max_colour = pow (2, lut_out->bit_depth()) - 1;
struct {
double x, y, z;
} s;
struct {
double r, g, b;
} d;
int* xyz_x = xyz_frame->data (0);
int* xyz_y = xyz_frame->data (1);
int* xyz_z = xyz_frame->data (2);
shared_ptr<ARGBFrame> argb_frame (new ARGBFrame (xyz_frame->size ()));
uint8_t* argb = argb_frame->data ();
for (int y = 0; y < xyz_frame->size().height; ++y) {
uint8_t* argb_line = argb;
for (int x = 0; x < xyz_frame->size().width; ++x) {
assert (*xyz_x >= 0 && *xyz_y >= 0 && *xyz_z >= 0 && *xyz_x < 4096 && *xyz_x < 4096 && *xyz_z < 4096);
/* In gamma LUT */
s.x = lut_in->lut()[*xyz_x++];
s.y = lut_in->lut()[*xyz_y++];
s.z = lut_in->lut()[*xyz_z++];
/* DCI companding */
s.x /= dci_coefficient;
s.y /= dci_coefficient;
s.z /= dci_coefficient;
/* XYZ to RGB */
d.r = ((s.x * colour_matrix[0][0]) + (s.y * colour_matrix[0][1]) + (s.z * colour_matrix[0][2]));
d.g = ((s.x * colour_matrix[1][0]) + (s.y * colour_matrix[1][1]) + (s.z * colour_matrix[1][2]));
d.b = ((s.x * colour_matrix[2][0]) + (s.y * colour_matrix[2][1]) + (s.z * colour_matrix[2][2]));
d.r = min (d.r, 1.0);
d.r = max (d.r, 0.0);
d.g = min (d.g, 1.0);
d.g = max (d.g, 0.0);
d.b = min (d.b, 1.0);
d.b = max (d.b, 0.0);
/* Out gamma LUT */
*argb_line++ = lut_out->lut()[(int) (d.b * max_colour)] * 0xff;
*argb_line++ = lut_out->lut()[(int) (d.g * max_colour)] * 0xff;
*argb_line++ = lut_out->lut()[(int) (d.r * max_colour)] * 0xff;
*argb_line++ = 0xff;
}
argb += argb_frame->stride ();
}
return argb_frame;
}
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