1 /////////////////////////////////////////////////////////////////////////// 2 // 3 // Copyright (c) 2003, Industrial Light & Magic, a division of Lucas 4 // Digital Ltd. LLC 5 // 6 // All rights reserved. 7 // 8 // Redistribution and use in source and binary forms, with or without 9 // modification, are permitted provided that the following conditions are 10 // met: 11 // * Redistributions of source code must retain the above copyright 12 // notice, this list of conditions and the following disclaimer. 13 // * Redistributions in binary form must reproduce the above 14 // copyright notice, this list of conditions and the following disclaimer 15 // in the documentation and/or other materials provided with the 16 // distribution. 17 // * Neither the name of Industrial Light & Magic nor the names of 18 // its contributors may be used to endorse or promote products derived 19 // from this software without specific prior written permission. 20 // 21 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 24 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 25 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 26 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 27 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 31 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 // 33 /////////////////////////////////////////////////////////////////////////// 34 35 36 #ifndef INCLUDED_IMF_CHROMATICITIES_H 37 #define INCLUDED_IMF_CHROMATICITIES_H 38 39 //----------------------------------------------------------------------------- 40 // 41 // CIE (x,y) chromaticities, and conversions between 42 // RGB tiples and CIE XYZ tristimulus values. 43 // 44 //----------------------------------------------------------------------------- 45 46 #include "ImathVec.h" 47 #include "ImathMatrix.h" 48 49 namespace Imf { 50 51 52 struct Chromaticities 53 { 54 //----------------------------------------------- 55 // The CIE x and y coordinates of the RGB triples 56 // (1,0,0), (0,1,0), (0,0,1) and (1,1,1). 57 //----------------------------------------------- 58 59 Imath::V2f red; 60 Imath::V2f green; 61 Imath::V2f blue; 62 Imath::V2f white; 63 64 //-------------------------------------------- 65 // Default constructor produces chromaticities 66 // according to Rec. ITU-R BT.709-3 67 //-------------------------------------------- 68 69 Chromaticities (const Imath::V2f &red = Imath::V2f (0.6400f, 0.3300f), 70 const Imath::V2f &green = Imath::V2f (0.3000f, 0.6000f), 71 const Imath::V2f &blue = Imath::V2f (0.1500f, 0.0600f), 72 const Imath::V2f &white = Imath::V2f (0.3127f, 0.3290f)); 73 }; 74 75 76 // 77 // Conversions between RGB and CIE XYZ 78 // 79 // RGB to XYZ: 80 // 81 // Given a set of chromaticities, c, and the luminance, Y, of the RGB 82 // triple (1,1,1), or "white", RGBtoXYZ(c,Y) computes a matrix, M, so 83 // that multiplying an RGB value, v, with M produces an equivalent 84 // XYZ value, w. (w == v * M) 85 // 86 // If we define that 87 // 88 // (Xr, Yr, Zr) == (1, 0, 0) * M 89 // (Xg, Yg, Zg) == (0, 1, 0) * M 90 // (Xb, Yb, Zb) == (0, 0, 1) * M 91 // (Xw, Yw, Zw) == (1, 1, 1) * M, 92 // 93 // then the following statements are true: 94 // 95 // Xr / (Xr + Yr + Zr) == c.red.x 96 // Yr / (Xr + Yr + Zr) == c.red.y 97 // 98 // Xg / (Xg + Yg + Zg) == c.red.x 99 // Yg / (Xg + Yg + Zg) == c.red.y 100 // 101 // Xb / (Xb + Yb + Zb) == c.red.x 102 // Yb / (Xb + Yb + Zb) == c.red.y 103 // 104 // Xw / (Xw + Yw + Zw) == c.red.x 105 // Yw / (Xw + Yw + Zw) == c.red.y 106 // 107 // Yw == Y. 108 // 109 // XYZ to RGB: 110 // 111 // YYZtoRGB(c,Y) returns RGBtoXYZ(c,Y).inverse(). 112 // 113 114 Imath::M44f RGBtoXYZ (const Chromaticities chroma, float Y); 115 Imath::M44f XYZtoRGB (const Chromaticities chroma, float Y); 116 117 118 } // namespace Imf 119 120 #endif 121
