Change colourspace handling round a bit:1.0-colour-cleanup

- move the essence of GammaLUT into TransferFunction and handle
  different bit depths more neatly
- add ColourConversion to describe input gamma correction, colour
  transformation and then output gamma correction in one class.
- add default ColourConversions for sRGB->XYZ, Rec709->XYZ and
  XYZ->RGB.

1 files changed, 62 insertions, 0 deletions

diff --git a/src/modified_gamma_transfer_function.h b/src/modified_gamma_transfer_function.h
new file mode 100644
index 00000000..0c6a6b84
--- /dev/null
+++ b/src/modified_gamma_transfer_function.h
@@ -0,0 +1,62 @@
+/*
+    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 "transfer_function.h"
+
+namespace dcp {
+
+/** A transfer function which for an input x gives an output y where
+ *
+ *  y = x / B                      for x <= threshold
+ *  y = ((x + A) / (1 + A))^power  for x >  threshold
+ */
+class ModifiedGammaTransferFunction : public TransferFunction
+{
+public:
+	ModifiedGammaTransferFunction (float power, float threshold, float A, float B);
+
+	float power () const {
+		return _power;
+	}
+
+	float threshold () const {
+		return _threshold;
+	}
+
+	float A () const {
+		return _A;
+	}
+
+	float B () const {
+		return _B;
+	}
+
+	bool about_equal (boost::shared_ptr<const TransferFunction>, float epsilon) const;
+	
+protected:
+	float * make_lut (int bit_depth) const;
+	
+private:
+	float _power;
+	float _threshold;
+	float _A;
+	float _B;
+};
+
+}