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Diffstat (limited to 'Source/OpenEXR/IlmImf/ImfChromaticities.cpp')
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diff --git a/Source/OpenEXR/IlmImf/ImfChromaticities.cpp b/Source/OpenEXR/IlmImf/ImfChromaticities.cpp new file mode 100644 index 0000000..2db9d0e --- /dev/null +++ b/Source/OpenEXR/IlmImf/ImfChromaticities.cpp @@ -0,0 +1,135 @@ +/////////////////////////////////////////////////////////////////////////// +// +// 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. +// +/////////////////////////////////////////////////////////////////////////// + + +//----------------------------------------------------------------------------- +// +// CIE (x,y) chromaticities, and conversions between +// RGB tiples and CIE XYZ tristimulus values. +// +//----------------------------------------------------------------------------- + +#include <ImfChromaticities.h> + +namespace Imf { + + +Chromaticities::Chromaticities (const Imath::V2f &red, + const Imath::V2f &green, + const Imath::V2f &blue, + const Imath::V2f &white) +: + red (red), + green (green), + blue (blue), + white (white) +{ + // empty +} + + +Imath::M44f +RGBtoXYZ (const Chromaticities chroma, float Y) +{ + // + // For an explanation of how the color conversion matrix is derived, + // see Roy Hall, "Illumination and Color in Computer Generated Imagery", + // Springer-Verlag, 1989, chapter 3, "Perceptual Response"; and + // Charles A. Poynton, "A Technical Introduction to Digital Video", + // John Wiley & Sons, 1996, chapter 7, "Color science for video". + // + + // + // X and Z values of RGB value (1, 1, 1), or "white" + // + + float X = chroma.white.x * Y / chroma.white.y; + float Z = (1 - chroma.white.x - chroma.white.y) * Y / chroma.white.y; + + // + // Scale factors for matrix rows + // + + float d = chroma.red.x * (chroma.blue.y - chroma.green.y) + + chroma.blue.x * (chroma.green.y - chroma.red.y) + + chroma.green.x * (chroma.red.y - chroma.blue.y); + + float Sr = (X * (chroma.blue.y - chroma.green.y) - + chroma.green.x * (Y * (chroma.blue.y - 1) + + chroma.blue.y * (X + Z)) + + chroma.blue.x * (Y * (chroma.green.y - 1) + + chroma.green.y * (X + Z))) / d; + + float Sg = (X * (chroma.red.y - chroma.blue.y) + + chroma.red.x * (Y * (chroma.blue.y - 1) + + chroma.blue.y * (X + Z)) - + chroma.blue.x * (Y * (chroma.red.y - 1) + + chroma.red.y * (X + Z))) / d; + + float Sb = (X * (chroma.green.y - chroma.red.y) - + chroma.red.x * (Y * (chroma.green.y - 1) + + chroma.green.y * (X + Z)) + + chroma.green.x * (Y * (chroma.red.y - 1) + + chroma.red.y * (X + Z))) / d; + + // + // Assemble the matrix + // + + Imath::M44f M; + + M[0][0] = Sr * chroma.red.x; + M[0][1] = Sr * chroma.red.y; + M[0][2] = Sr * (1 - chroma.red.x - chroma.red.y); + + M[1][0] = Sg * chroma.green.x; + M[1][1] = Sg * chroma.green.y; + M[1][2] = Sg * (1 - chroma.green.x - chroma.green.y); + + M[2][0] = Sb * chroma.blue.x; + M[2][1] = Sb * chroma.blue.y; + M[2][2] = Sb * (1 - chroma.blue.x - chroma.blue.y); + + return M; +} + + +Imath::M44f +XYZtoRGB (const Chromaticities chroma, float Y) +{ + return RGBtoXYZ (chroma, Y).inverse(); +} + + +} // namespace Imf |