--- /dev/null
+///////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2003, Industrial Light & Magic, a division of Lucas
+// Digital Ltd. LLC
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Industrial Light & Magic nor the names of
+// its contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+///////////////////////////////////////////////////////////////////////////
+
+
+#ifndef INCLUDED_IMF_CHROMATICITIES_H
+#define INCLUDED_IMF_CHROMATICITIES_H
+
+//-----------------------------------------------------------------------------
+//
+// CIE (x,y) chromaticities, and conversions between
+// RGB tiples and CIE XYZ tristimulus values.
+//
+//-----------------------------------------------------------------------------
+
+#include "ImathVec.h"
+#include "ImathMatrix.h"
+
+namespace Imf {
+
+
+struct Chromaticities
+{
+ Imath::V2f red;
+ Imath::V2f green;
+ Imath::V2f blue;
+ Imath::V2f white;
+
+ Chromaticities (const Imath::V2f &red = Imath::V2f (0.6400f, 0.3300f),
+ const Imath::V2f &green = Imath::V2f (0.3000f, 0.6000f),
+ const Imath::V2f &blue = Imath::V2f (0.1500f, 0.0600f),
+ const Imath::V2f &white = Imath::V2f (0.3127f, 0.3290f));
+};
+
+
+//
+// Conversions between RGB and CIE XYZ
+//
+// RGB to XYZ:
+//
+// Given a set of chromaticities, c, and the luminance, Y, of the RGB
+// triple (1,1,1), or "white", RGBtoXYZ(c,Y) computes a matrix, M, so
+// that multiplying an RGB value, v, with M produces an equivalent
+// XYZ value, w. (w == v * M)
+//
+// If we define that
+//
+// (Xr, Yr, Zr) == (1, 0, 0) * M
+// (Xg, Yg, Zg) == (0, 1, 0) * M
+// (Xb, Yb, Zb) == (0, 0, 1) * M
+// (Xw, Yw, Zw) == (1, 1, 1) * M,
+//
+// then the following statements are true:
+//
+// Xr / (Xr + Yr + Zr) == c.red.x
+// Yr / (Xr + Yr + Zr) == c.red.y
+//
+// Xg / (Xg + Yg + Zg) == c.red.x
+// Yg / (Xg + Yg + Zg) == c.red.y
+//
+// Xb / (Xb + Yb + Zb) == c.red.x
+// Yb / (Xb + Yb + Zb) == c.red.y
+//
+// Xw / (Xw + Yw + Zw) == c.red.x
+// Yw / (Xw + Yw + Zw) == c.red.y
+//
+// Yw == Y.
+//
+// XYZ to RGB:
+//
+// YYZtoRGB(c,Y) returns RGBtoXYZ(c,Y).inverse().
+//
+// Warning:
+//
+// It would seem that RGBtoXYZ() and XYZtoRGB() are all you need
+// to convert RGB values with one set of primary and white point
+// chromaticities into perceptually equivalent RGB values with
+// different primary and white point chromaticities:
+//
+// M44f M = RGBtoXYZ (chromaticities1, Y1) *
+// XYZtoRGB (chromaticities2, Y2);
+//
+// However, this simple conversion does not account for white point
+// adaptation, and produces undesirable results. The proper thing
+// to do is to perform a Bradford or a von Kries transform, which
+// moves the white point of the original color space to the white
+// point of the destination color space, dragging other colors with
+// it in a sensible fashion.
+//
+
+Imath::M44f RGBtoXYZ (const Chromaticities chroma, float Y);
+Imath::M44f XYZtoRGB (const Chromaticities chroma, float Y);
+
+
+} // namespace Imf
+
+#endif