Express colour conversions as chromaticities and adjust so that

everything is specified as something_to_xyz and then you can get
an inverse LUT if you want one.

1 files changed, 54 insertions, 0 deletions

diff --git a/src/chromaticity.h b/src/chromaticity.h
new file mode 100644
index 00000000..89b71936
--- /dev/null
+++ b/src/chromaticity.h
@@ -0,0 +1,54 @@
+/*
+    Copyright (C) 2015 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.
+
+*/
+
+#ifndef DCP_CHROMATICITY_H
+#define DCP_CHROMATICITY_H
+
+#include <cmath>
+
+namespace dcp {
+
+class Chromaticity
+{
+public:
+	Chromaticity ()
+		: x (0)
+		, y (0)
+	{}
+
+	Chromaticity (double x_, double y_)
+		: x (x_)
+		, y (y_)
+	{}
+		
+	double x;
+	double y;
+
+	double z () const {
+		return 1 - x - y;
+	}
+
+	bool about_equal (Chromaticity const & other, float epsilon) const {
+		return std::fabs (x - other.x) < epsilon && std::fabs (y - other.y) < epsilon;
+	}
+};
+
+}
+
+#endif