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, 75 insertions, 0 deletions

diff --git a/src/colour_conversion.cc b/src/colour_conversion.cc
new file mode 100644
index 00000000..28edf9bc
--- /dev/null
+++ b/src/colour_conversion.cc
@@ -0,0 +1,75 @@
+/*
+    Copyright (C) 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 "colour_conversion.h"
+#include "gamma_transfer_function.h"
+#include "modified_gamma_transfer_function.h"
+#include "colour_matrix.h"
+
+using boost::shared_ptr;
+using namespace dcp;
+
+ColourConversion ColourConversion::srgb_to_xyz (
+	shared_ptr<const TransferFunction> (new ModifiedGammaTransferFunction (2.4, 0.04045, 0.055, 12.92)),
+	dcp::colour_matrix::srgb_to_xyz,
+	shared_ptr<const TransferFunction> (new GammaTransferFunction (2.6))
+	);
+
+/* XXX: what sort of RGB is this...? */
+ColourConversion ColourConversion::xyz_to_rgb (
+	shared_ptr<const TransferFunction> (new GammaTransferFunction (2.6)),
+	dcp::colour_matrix::xyz_to_rgb,
+	shared_ptr<const TransferFunction> (new GammaTransferFunction (2.2))
+	);
+
+ColourConversion ColourConversion::rec709_to_xyz (
+	shared_ptr<const TransferFunction> (new ModifiedGammaTransferFunction (2.4, 0.081, 0.099, 4.5)),
+	dcp::colour_matrix::srgb_to_xyz,
+	shared_ptr<const TransferFunction> (new GammaTransferFunction (2.6))
+	);
+
+ColourConversion::ColourConversion (
+	shared_ptr<const TransferFunction> in,
+	double const matrix[3][3],
+	shared_ptr<const TransferFunction> out
+	)
+	: _in (in)
+	, _matrix (3, 3)
+	, _out (out)
+{
+	for (int i = 0; i < 3; ++i) {
+		for (int j = 0; j < 3; ++j) {
+			_matrix (i, j) = matrix[i][j];
+		}
+	}
+}
+
+bool
+ColourConversion::about_equal (ColourConversion const & other, float epsilon) const
+{
+	for (int i = 0; i < 3; ++i) {
+		for (int j = 0; j < 3; ++j) {
+			if (fabs (_matrix(i, j) - other._matrix(i, j)) > epsilon) {
+				return false;
+			}
+		}
+	}
+
+	return _in->about_equal (other._in, epsilon) && _out->about_equal (other._out, epsilon);
+}