/src/FreeImage/Source/OpenEXR/IlmImf/ImfChromaticities.cpp
https://bitbucket.org/cabalistic/ogredeps/ · C++ · 135 lines · 54 code · 25 blank · 56 comment · 0 complexity · 792a376eb41324ebf75882d62c131529 MD5 · raw file
- ///////////////////////////////////////////////////////////////////////////
- //
- // 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