/*
    Copyright 2012 Christian Henning, Andreas Pokorny, Lubomir Bourdev
    Use, modification and distribution are subject to the Boost Software License,
    Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
    http://www.boost.org/LICENSE_1_0.txt).
*/

/*************************************************************************************************/

#ifndef BOOST_GIL_EXTENSION_TOOLBOX_COLOR_CONVERTERS_RGB_TO_LUMINANCE_HPP
#define BOOST_GIL_EXTENSION_TOOLBOX_COLOR_CONVERTERS_RGB_TO_LUMINANCE_HPP

////////////////////////////////////////////////////////////////////////////////////////
/// \file
/// \brief
/// \author Christian Henning, Andreas Pokorny, Lubomir Bourdev \n
///
/// \date 2012 \n
///
////////////////////////////////////////////////////////////////////////////////////////

#include <boost/gil/color_convert.hpp>

namespace boost{ namespace gil { namespace detail {

/// - performance specialization double
/// - to eliminate compiler warning 4244
template <typename GrayChannelValue>
struct rgb_to_luminance_fn< double, double, double, GrayChannelValue >
{
    GrayChannelValue operator()( const double& red
                               , const double& green
                               , const double& blue    ) const
   {
      return channel_convert<GrayChannelValue>( red * 0.30 + green * 0.59 + blue * 0.11 );
   }
};

} // namespace detail
} // namespace gil
} // namespace boost

#endif // BOOST_GIL_EXTENSION_TOOLBOX_COLOR_CONVERTERS_RGB_TO_LUMINANCE_HPP
