2 Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
4 This file is part of libdcp.
6 libdcp is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 libdcp is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with libdcp. If not, see <http://www.gnu.org/licenses/>.
20 #include "modified_gamma_transfer_function.h"
24 using boost::shared_ptr;
25 using boost::dynamic_pointer_cast;
28 ModifiedGammaTransferFunction::ModifiedGammaTransferFunction (double power, double threshold, double A, double B)
30 , _threshold (threshold)
38 ModifiedGammaTransferFunction::make_lut (int bit_depth, bool inverse) const
40 int const bit_length = int(std::pow(2.0f, bit_depth));
41 double* lut = new double[bit_length];
43 double const threshold = _threshold / _B;
44 for (int i = 0; i < bit_length; ++i) {
45 double const p = static_cast<double> (i) / (bit_length - 1);
47 lut[i] = (1 + _A) * pow (p, 1 / _power) - _A;
53 for (int i = 0; i < bit_length; ++i) {
54 double const p = static_cast<double> (i) / (bit_length - 1);
56 lut[i] = pow ((p + _A) / (1 + _A), _power);
67 ModifiedGammaTransferFunction::about_equal (shared_ptr<const TransferFunction> other, double epsilon) const
69 shared_ptr<const ModifiedGammaTransferFunction> o = dynamic_pointer_cast<const ModifiedGammaTransferFunction> (other);
75 fabs (_power - o->_power) < epsilon &&
76 fabs (_threshold - o->_threshold) < epsilon &&
77 fabs (_A - o->_A) < epsilon &&
78 fabs (_B - o->_B) < epsilon