/src/FreeImage/Source/OpenEXR/IlmImf/ImfChromaticities.h

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  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,
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  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
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  31. // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32. //
  33. ///////////////////////////////////////////////////////////////////////////
  34. #ifndef INCLUDED_IMF_CHROMATICITIES_H
  35. #define INCLUDED_IMF_CHROMATICITIES_H
  36. //-----------------------------------------------------------------------------
  37. //
  38. // CIE (x,y) chromaticities, and conversions between
  39. // RGB tiples and CIE XYZ tristimulus values.
  40. //
  41. //-----------------------------------------------------------------------------
  42. #include "ImathVec.h"
  43. #include "ImathMatrix.h"
  44. namespace Imf {
  45. struct Chromaticities
  46. {
  47. //-----------------------------------------------
  48. // The CIE x and y coordinates of the RGB triples
  49. // (1,0,0), (0,1,0), (0,0,1) and (1,1,1).
  50. //-----------------------------------------------
  51. Imath::V2f red;
  52. Imath::V2f green;
  53. Imath::V2f blue;
  54. Imath::V2f white;
  55. //--------------------------------------------
  56. // Default constructor produces chromaticities
  57. // according to Rec. ITU-R BT.709-3
  58. //--------------------------------------------
  59. Chromaticities (const Imath::V2f &red = Imath::V2f (0.6400f, 0.3300f),
  60. const Imath::V2f &green = Imath::V2f (0.3000f, 0.6000f),
  61. const Imath::V2f &blue = Imath::V2f (0.1500f, 0.0600f),
  62. const Imath::V2f &white = Imath::V2f (0.3127f, 0.3290f));
  63. };
  64. //
  65. // Conversions between RGB and CIE XYZ
  66. //
  67. // RGB to XYZ:
  68. //
  69. // Given a set of chromaticities, c, and the luminance, Y, of the RGB
  70. // triple (1,1,1), or "white", RGBtoXYZ(c,Y) computes a matrix, M, so
  71. // that multiplying an RGB value, v, with M produces an equivalent
  72. // XYZ value, w. (w == v * M)
  73. //
  74. // If we define that
  75. //
  76. // (Xr, Yr, Zr) == (1, 0, 0) * M
  77. // (Xg, Yg, Zg) == (0, 1, 0) * M
  78. // (Xb, Yb, Zb) == (0, 0, 1) * M
  79. // (Xw, Yw, Zw) == (1, 1, 1) * M,
  80. //
  81. // then the following statements are true:
  82. //
  83. // Xr / (Xr + Yr + Zr) == c.red.x
  84. // Yr / (Xr + Yr + Zr) == c.red.y
  85. //
  86. // Xg / (Xg + Yg + Zg) == c.red.x
  87. // Yg / (Xg + Yg + Zg) == c.red.y
  88. //
  89. // Xb / (Xb + Yb + Zb) == c.red.x
  90. // Yb / (Xb + Yb + Zb) == c.red.y
  91. //
  92. // Xw / (Xw + Yw + Zw) == c.red.x
  93. // Yw / (Xw + Yw + Zw) == c.red.y
  94. //
  95. // Yw == Y.
  96. //
  97. // XYZ to RGB:
  98. //
  99. // YYZtoRGB(c,Y) returns RGBtoXYZ(c,Y).inverse().
  100. //
  101. Imath::M44f RGBtoXYZ (const Chromaticities chroma, float Y);
  102. Imath::M44f XYZtoRGB (const Chromaticities chroma, float Y);
  103. } // namespace Imf
  104. #endif