Comment fixes.

[libdcp.git] / src / gamma_transfer_function.cc

diff --git a/src/gamma_transfer_function.cc b/src/gamma_transfer_function.cc
index b4aa20f1bdb839f680282b1a1d546556fc66925e..1875221e3ccc296c2b3087519fb9ee9cf8271b4f 100644 (file)
--- a/src/gamma_transfer_function.cc
+++ b/src/gamma_transfer_function.cc
@@ -1,55 +1,80 @@
 /*
-    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2021 Carl Hetherington <cth@carlh.net>
 
-    This program is free software; you can redistribute it and/or modify
+    This file is part of libdcp.
+
+    libdcp 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,
+    libdcp 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.
+    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
 
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
 */
 
+
+/** @file  src/gamma_transfer_function.cc
+ *  @brief GammaTransferFunction class
+ */
+
+
 #include "gamma_transfer_function.h"
 #include <cmath>
 
+
 using std::pow;
-using boost::shared_ptr;
-using boost::dynamic_pointer_cast;
+using std::shared_ptr;
+using std::dynamic_pointer_cast;
 using namespace dcp;
 
-GammaTransferFunction::GammaTransferFunction (float gamma)
+
+GammaTransferFunction::GammaTransferFunction (double gamma)
        : _gamma (gamma)
 {
 
 }
 
-float *
-GammaTransferFunction::make_lut (int bit_depth) const
+
+double *
+GammaTransferFunction::make_lut (int bit_depth, bool inverse) const
 {
-       int const bit_length = pow (2, bit_depth);
-       float* lut = new float[int(std::pow(2.0f, bit_depth))];
+       int const bit_length = int(std::pow(2.0f, bit_depth));
+       auto lut = new double[bit_length];
+       double const gamma = inverse ? (1 / _gamma) : _gamma;
        for (int i = 0; i < bit_length; ++i) {
-               lut[i] = pow(float(i) / (bit_length - 1), _gamma);
+               lut[i] = pow(double(i) / (bit_length - 1), gamma);
        }
 
        return lut;
 }
 
+
 bool
-GammaTransferFunction::about_equal (shared_ptr<const TransferFunction> other, float epsilon) const
+GammaTransferFunction::about_equal (shared_ptr<const TransferFunction> other, double epsilon) const
 {
-       shared_ptr<const GammaTransferFunction> o = dynamic_pointer_cast<const GammaTransferFunction> (other);
+       auto o = dynamic_pointer_cast<const GammaTransferFunction>(other);
        if (!o) {
                return false;
        }
 
-       return fabs (_gamma - o->_gamma) < epsilon;
+       return fabs(_gamma - o->_gamma) < epsilon;
 }