boost/gil/extension/toolbox/color_spaces/xyz.hpp

   1 //
   2 // Copyright 2012 Chung-Lin Wen, Davide Anastasia
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 #ifndef BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_XYZ_HPP
   9 #define BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_XYZ_HPP
  10
  11 #include <boost/gil/color_convert.hpp>
  12 #include <boost/gil/typedefs.hpp>
  13 #include <boost/gil/detail/mp11.hpp>
  14
  15 namespace boost{ namespace gil {
  16
  17 /// \addtogroup ColorNameModel
  18 /// \{
  19 namespace xyz_color_space
  20 {
  21 /// \brief x Color Component
  22 struct x_t {};
  23 /// \brief y Color Component
  24 struct y_t {};
  25 /// \brief z Color Component
  26 struct z_t {};
  27 }
  28 /// \}
  29
  30 /// \ingroup ColorSpaceModel
  31 using xyz_t = mp11::mp_list
  32 <
  33     xyz_color_space::x_t,
  34     xyz_color_space::y_t,
  35     xyz_color_space::z_t
  36 >;
  37
  38 /// \ingroup LayoutModel
  39 using xyz_layout_t = layout<xyz_t>;
  40
  41 GIL_DEFINE_ALL_TYPEDEFS(32f, float32_t, xyz)
  42
  43 /// \ingroup ColorConvert
  44 /// \brief RGB to XYZ
  45 /// <a href="http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html">Link</a>
  46 /// \note rgb_t is assumed to be sRGB D65
  47 template <>
  48 struct default_color_converter_impl< rgb_t, xyz_t >
  49 {
  50 private:
  51     BOOST_FORCEINLINE
  52     float32_t inverse_companding(float32_t sample) const
  53     {
  54         if ( sample > 0.04045f )
  55         {
  56             return powf((( sample + 0.055f ) / 1.055f ), 2.4f);
  57         }
  58         else
  59         {
  60             return ( sample / 12.92f );
  61         }
  62     }
  63
  64 public:
  65     template <typename P1, typename P2>
  66     void operator()( const P1& src, P2& dst ) const
  67     {
  68         using namespace xyz_color_space;
  69
  70         float32_t red(
  71             inverse_companding(
  72                 channel_convert<float32_t>(get_color(src, red_t()))));
  73         float32_t green(
  74             inverse_companding(
  75                 channel_convert<float32_t>(get_color(src, green_t()))));
  76         float32_t blue(
  77             inverse_companding(
  78                 channel_convert<float32_t>(get_color(src, blue_t()))));
  79
  80         get_color( dst, x_t() ) =
  81                 red * 0.4124564f +
  82                 green * 0.3575761f +
  83                 blue * 0.1804375f;
  84         get_color( dst, y_t() ) =
  85                 red * 0.2126729f +
  86                 green * 0.7151522f +
  87                 blue * 0.0721750f;
  88         get_color( dst, z_t() ) =
  89                 red * 0.0193339f +
  90                 green * 0.1191920f +
  91                 blue * 0.9503041f;
  92     }
  93 };
  94
  95 /// \ingroup ColorConvert
  96 /// \brief XYZ to RGB
  97 template <>
  98 struct default_color_converter_impl<xyz_t,rgb_t>
  99 {
 100 private:
 101     BOOST_FORCEINLINE
 102     float32_t companding(float32_t sample) const
 103     {
 104         if ( sample > 0.0031308f )
 105         {
 106             return ( 1.055f * powf( sample, 1.f/2.4f ) - 0.055f );
 107         }
 108         else
 109         {
 110             return ( 12.92f * sample );
 111         }
 112     }
 113
 114 public:
 115     template <typename P1, typename P2>
 116     void operator()( const P1& src, P2& dst) const
 117     {
 118         using namespace xyz_color_space;
 119
 120         // Note: ideally channel_convert should be compiled out, because xyz_t
 121         // is float32_t natively only
 122         float32_t x( channel_convert<float32_t>( get_color( src, x_t() ) ) );
 123         float32_t y( channel_convert<float32_t>( get_color( src, y_t() ) ) );
 124         float32_t z( channel_convert<float32_t>( get_color( src, z_t() ) ) );
 125
 126         get_color(dst,red_t())  =
 127                 channel_convert<typename color_element_type<P2, red_t>::type>(
 128                     companding( x *  3.2404542f +
 129                                 y * -1.5371385f +
 130                                 z * -0.4985314f )
 131                     );
 132         get_color(dst,green_t()) =
 133                 channel_convert<typename color_element_type<P2, green_t>::type>(
 134                     companding( x * -0.9692660f +
 135                                 y *  1.8760108f +
 136                                 z *  0.0415560f )
 137                     );
 138         get_color(dst,blue_t()) =
 139                 channel_convert<typename color_element_type<P2, blue_t>::type>(
 140                     companding( x *  0.0556434f +
 141                                 y * -0.2040259f +
 142                                 z *  1.0572252f )
 143                     );
 144     }
 145 };
 146
 147 } // namespace gil
 148 } // namespace boost
 149
 150 #endif // BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_XYZ_HPP