PBRT
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00001 00002 // 00003 // Copyright (c) 2003, Industrial Light & Magic, a division of Lucas 00004 // Digital Ltd. LLC 00005 // 00006 // All rights reserved. 00007 // 00008 // Redistribution and use in source and binary forms, with or without 00009 // modification, are permitted provided that the following conditions are 00010 // met: 00011 // * Redistributions of source code must retain the above copyright 00012 // notice, this list of conditions and the following disclaimer. 00013 // * Redistributions in binary form must reproduce the above 00014 // copyright notice, this list of conditions and the following disclaimer 00015 // in the documentation and/or other materials provided with the 00016 // distribution. 00017 // * Neither the name of Industrial Light & Magic nor the names of 00018 // its contributors may be used to endorse or promote products derived 00019 // from this software without specific prior written permission. 00020 // 00021 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 00022 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00023 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 00024 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 00025 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 00026 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 00027 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 00028 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 00029 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 00030 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 00031 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 00032 // 00034 00035 00036 #ifndef INCLUDED_IMF_CHROMATICITIES_H 00037 #define INCLUDED_IMF_CHROMATICITIES_H 00038 00039 //----------------------------------------------------------------------------- 00040 // 00041 // CIE (x,y) chromaticities, and conversions between 00042 // RGB tiples and CIE XYZ tristimulus values. 00043 // 00044 //----------------------------------------------------------------------------- 00045 00046 #include "ImathVec.h" 00047 #include "ImathMatrix.h" 00048 00049 namespace Imf { 00050 00051 00052 struct Chromaticities 00053 { 00054 //----------------------------------------------- 00055 // The CIE x and y coordinates of the RGB triples 00056 // (1,0,0), (0,1,0), (0,0,1) and (1,1,1). 00057 //----------------------------------------------- 00058 00059 Imath::V2f red; 00060 Imath::V2f green; 00061 Imath::V2f blue; 00062 Imath::V2f white; 00063 00064 //-------------------------------------------- 00065 // Default constructor produces chromaticities 00066 // according to Rec. ITU-R BT.709-3 00067 //-------------------------------------------- 00068 00069 Chromaticities (const Imath::V2f &red = Imath::V2f (0.6400f, 0.3300f), 00070 const Imath::V2f &green = Imath::V2f (0.3000f, 0.6000f), 00071 const Imath::V2f &blue = Imath::V2f (0.1500f, 0.0600f), 00072 const Imath::V2f &white = Imath::V2f (0.3127f, 0.3290f)); 00073 }; 00074 00075 00076 // 00077 // Conversions between RGB and CIE XYZ 00078 // 00079 // RGB to XYZ: 00080 // 00081 // Given a set of chromaticities, c, and the luminance, Y, of the RGB 00082 // triple (1,1,1), or "white", RGBtoXYZ(c,Y) computes a matrix, M, so 00083 // that multiplying an RGB value, v, with M produces an equivalent 00084 // XYZ value, w. (w == v * M) 00085 // 00086 // If we define that 00087 // 00088 // (Xr, Yr, Zr) == (1, 0, 0) * M 00089 // (Xg, Yg, Zg) == (0, 1, 0) * M 00090 // (Xb, Yb, Zb) == (0, 0, 1) * M 00091 // (Xw, Yw, Zw) == (1, 1, 1) * M, 00092 // 00093 // then the following statements are true: 00094 // 00095 // Xr / (Xr + Yr + Zr) == c.red.x 00096 // Yr / (Xr + Yr + Zr) == c.red.y 00097 // 00098 // Xg / (Xg + Yg + Zg) == c.red.x 00099 // Yg / (Xg + Yg + Zg) == c.red.y 00100 // 00101 // Xb / (Xb + Yb + Zb) == c.red.x 00102 // Yb / (Xb + Yb + Zb) == c.red.y 00103 // 00104 // Xw / (Xw + Yw + Zw) == c.red.x 00105 // Yw / (Xw + Yw + Zw) == c.red.y 00106 // 00107 // Yw == Y. 00108 // 00109 // XYZ to RGB: 00110 // 00111 // YYZtoRGB(c,Y) returns RGBtoXYZ(c,Y).inverse(). 00112 // 00113 00114 Imath::M44f RGBtoXYZ (const Chromaticities chroma, float Y); 00115 Imath::M44f XYZtoRGB (const Chromaticities chroma, float Y); 00116 00117 00118 } // namespace Imf 00119 00120 #endif