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/*
Copyright (C) 2012-2014 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 "gamma_lut.h"
#include "lut_cache.h"
#include <cmath>
using namespace dcp;
LUTCache<GammaLUT> GammaLUT::cache;
GammaLUT::GammaLUT (int bit_depth, float gamma, bool linearised)
: _bit_depth (bit_depth)
, _gamma (gamma)
, _linearised (linearised)
{
_lut = new float[int(std::pow(2.0f, _bit_depth))];
int const bit_length = pow (2, _bit_depth);
if (_linearised) {
for (int i = 0; i < bit_length; ++i) {
float const p = static_cast<float> (i) / (bit_length - 1);
if (p > 0.04045) {
_lut[i] = pow ((p + 0.055) / 1.055, gamma);
} else {
_lut[i] = p / 12.92;
}
}
} else {
for (int i = 0; i < bit_length; ++i) {
_lut[i] = pow(float(i) / (bit_length - 1), gamma);
}
}
}
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