2 Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 #include "gamma_transfer_function.h"
24 using boost::shared_ptr;
25 using boost::dynamic_pointer_cast;
28 GammaTransferFunction::GammaTransferFunction (bool inverse, double gamma)
29 : TransferFunction (inverse)
36 GammaTransferFunction::make_lut (int bit_depth) const
38 int const bit_length = pow (2, bit_depth);
39 double* lut = new double[int(std::pow(2.0f, bit_depth))];
40 double const gamma = _inverse ? (1 / _gamma) : _gamma;
41 for (int i = 0; i < bit_length; ++i) {
42 lut[i] = pow(double(i) / (bit_length - 1), gamma);
49 GammaTransferFunction::about_equal (shared_ptr<const TransferFunction> other, double epsilon) const
51 if (!TransferFunction::about_equal (other, epsilon)) {
55 shared_ptr<const GammaTransferFunction> o = dynamic_pointer_cast<const GammaTransferFunction> (other);
60 return fabs (_gamma - o->_gamma) < epsilon;