Rename lut -> double_lut.

[libdcp.git] / src / gamma_transfer_function.cc

diff --git a/src/gamma_transfer_function.cc b/src/gamma_transfer_function.cc
index c7c16f24be4281c5d4d2b76f90f3c02e6e3d0378..83c9929f2ae3247ca82c2e825d9d4f3e08f3b6bc 100644 (file)
--- a/src/gamma_transfer_function.cc
+++ b/src/gamma_transfer_function.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2021 Carl Hetherington <cth@carlh.net>
 
     This file is part of libdcp.
 
@@ -31,44 +31,52 @@
     files in the program, then also delete it here.
 */
 
+
 /** @file  src/gamma_transfer_function.cc
- *  @brief GammaTransferFunction class.
+ *  @brief GammaTransferFunction class
  */
 
+
 #include "gamma_transfer_function.h"
 #include <cmath>
 
+
+using std::dynamic_pointer_cast;
 using std::pow;
 using std::shared_ptr;
-using std::dynamic_pointer_cast;
+using std::vector;
 using namespace dcp;
 
+
 GammaTransferFunction::GammaTransferFunction (double gamma)
        : _gamma (gamma)
 {
 
 }
 
-double *
-GammaTransferFunction::make_lut (int bit_depth, bool inverse) const
+
+vector<double>
+GammaTransferFunction::make_double_lut(double from, double to, int bit_depth, bool inverse) const
 {
        int const bit_length = int(std::pow(2.0f, bit_depth));
-       double* lut = new double[bit_length];
+       auto lut = vector<double>(bit_length);
        double const gamma = inverse ? (1 / _gamma) : _gamma;
        for (int i = 0; i < bit_length; ++i) {
-               lut[i] = pow(double(i) / (bit_length - 1), gamma);
+               double const x = double(i) / (bit_length - 1);
+               lut[i] = pow((x * (to - from)) + from, gamma);
        }
 
        return lut;
 }
 
+
 bool
 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;
 }