ceph/src/boost/boost/gil/extension/toolbox/color_converters/rgb_to_luminance.hpp

   1 //
   2 // Copyright 2012 Christian Henning, Andreas Pokorny, Lubomir Bourdev
   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_CONVERTERS_RGB_TO_LUMINANCE_HPP
   9 #define BOOST_GIL_EXTENSION_TOOLBOX_COLOR_CONVERTERS_RGB_TO_LUMINANCE_HPP
  10
  11 #include <boost/gil/color_convert.hpp>
  12
  13 namespace boost{ namespace gil { namespace detail {
  14
  15 /// - performance specialization double
  16 /// - to eliminate compiler warning 4244
  17 template <typename GrayChannelValue>
  18 struct rgb_to_luminance_fn< double, double, double, GrayChannelValue >
  19 {
  20     GrayChannelValue operator()( const double& red
  21                                , const double& green
  22                                , const double& blue    ) const
  23    {
  24       return channel_convert<GrayChannelValue>( red * 0.30 + green * 0.59 + blue * 0.11 );
  25    }
  26 };
  27
  28 } // namespace detail
  29 } // namespace gil
  30 } // namespace boost
  31
  32 #endif