//
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// Copyright 2013 Juan V. Puertos G-Cluster, Christian Henning
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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#ifndef BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_YCBCR_HPP
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#define BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_YCBCR_HPP
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#include <boost/gil/extension/toolbox/metafunctions/get_num_bits.hpp>
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#include <boost/gil/color_convert.hpp>
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#include <boost/gil.hpp> // FIXME: Include what you use!
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#include <boost/gil/detail/mp11.hpp>
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#include <boost/config.hpp>
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#include <cstdint>
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#include <type_traits>
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namespace boost { namespace gil {
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/// \addtogroup ColorNameModel
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/// \{
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namespace ycbcr_601_color_space
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{
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/// \brief Luminance
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struct y_t {};
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/// \brief Blue chrominance component
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struct cb_t {};
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/// \brief Red chrominance component
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struct cr_t {};
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}
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namespace ycbcr_709_color_space
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{
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/// \brief Luminance
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struct y_t {};
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/// \brief Blue chrominance component
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struct cb_t {};
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/// \brief Red chrominance component
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struct cr_t {};
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}
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/// \}
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/// \ingroup ColorSpaceModel
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using ycbcr_601__t = mp11::mp_list
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<
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ycbcr_601_color_space::y_t,
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ycbcr_601_color_space::cb_t,
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ycbcr_601_color_space::cr_t
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>;
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/// \ingroup ColorSpaceModel
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using ycbcr_709__t = mp11::mp_list
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<
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ycbcr_709_color_space::y_t,
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ycbcr_709_color_space::cb_t,
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ycbcr_709_color_space::cr_t
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>;
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/// \ingroup LayoutModel
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using ycbcr_601__layout_t = boost::gil::layout<ycbcr_601__t>;
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using ycbcr_709__layout_t = boost::gil::layout<ycbcr_709__t>;
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//The channel depth is ALWAYS 8bits ofr YCbCr!
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BOOST_GIL_DEFINE_ALL_TYPEDEFS(8, uint8_t, ycbcr_601_)
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BOOST_GIL_DEFINE_ALL_TYPEDEFS(8, uint8_t, ycbcr_709_)
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namespace detail {
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// Source:boost/algorithm/clamp.hpp
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template<typename T>
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BOOST_CXX14_CONSTEXPR
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T const& clamp(
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T const& val,
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typename boost::mp11::mp_identity<T>::type const & lo,
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typename boost::mp11::mp_identity<T>::type const & hi)
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{
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// assert ( !p ( hi, lo )); // Can't assert p ( lo, hi ) b/c they might be equal
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auto const p = std::less<T>();
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return p(val, lo) ? lo : p(hi, val) ? hi : val;
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}
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} // namespace detail
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/*
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* 601 Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.601_conversion
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* 709 Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.709_conversion
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* (using values coming directly from ITU-R BT.601 recommendation)
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* (using values coming directly from ITU-R BT.709 recommendation)
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*/
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/**
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* @brief Convert YCbCr ITU.BT-601 to RGB.
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*/
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template<>
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struct default_color_converter_impl<ycbcr_601__t, rgb_t>
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{
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// Note: the RGB_t channels range can be set later on by the users. We dont want to cast to uint8_t or anything here.
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template < typename SRCP, typename DSTP >
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void operator()( const SRCP& src, DSTP& dst ) const
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{
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using dst_channel_t = typename channel_type<DSTP>::type;
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convert(src, dst, typename std::is_same
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<
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std::integral_constant<int, sizeof(dst_channel_t)>,
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std::integral_constant<int, 1>
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>::type());
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}
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private:
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// optimization for bit8 channels
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template< typename Src_Pixel
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, typename Dst_Pixel
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>
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void convert( const Src_Pixel& src
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, Dst_Pixel& dst
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, std::true_type // is 8 bit channel
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) const
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{
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using namespace ycbcr_601_color_space;
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using src_channel_t = typename channel_type<Src_Pixel>::type;
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using dst_channel_t = typename channel_type<Dst_Pixel>::type;
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src_channel_t y = channel_convert<src_channel_t>( get_color(src, y_t()));
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src_channel_t cb = channel_convert<src_channel_t>( get_color(src, cb_t()));
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src_channel_t cr = channel_convert<src_channel_t>( get_color(src, cr_t()));
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// The intermediate results of the formulas require at least 16bits of precission.
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std::int_fast16_t c = y - 16;
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std::int_fast16_t d = cb - 128;
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std::int_fast16_t e = cr - 128;
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std::int_fast16_t red = detail::clamp((( 298 * c + 409 * e + 128) >> 8), 0, 255);
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std::int_fast16_t green = detail::clamp((( 298 * c - 100 * d - 208 * e + 128) >> 8), 0, 255);
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std::int_fast16_t blue = detail::clamp((( 298 * c + 516 * d + 128) >> 8), 0, 255);
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get_color( dst, red_t() ) = (dst_channel_t) red;
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get_color( dst, green_t() ) = (dst_channel_t) green;
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get_color( dst, blue_t() ) = (dst_channel_t) blue;
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}
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template< typename Src_Pixel
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, typename Dst_Pixel
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>
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void convert( const Src_Pixel& src
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, Dst_Pixel& dst
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, std::false_type // is 8 bit channel
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) const
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{
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using namespace ycbcr_601_color_space;
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using dst_channel_t = typename channel_type<Dst_Pixel>::type;
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double y = get_color( src, y_t() );
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double cb = get_color( src, cb_t() );
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double cr = get_color( src, cr_t() );
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get_color(dst, red_t()) = static_cast<dst_channel_t>(
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detail::clamp(1.6438 * (y - 16.0) + 1.5960 * (cr -128.0), 0.0, 255.0));
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get_color(dst, green_t()) = static_cast<dst_channel_t>(
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detail::clamp(1.6438 * (y - 16.0) - 0.3917 * (cb - 128.0) + 0.8129 * (cr -128.0), 0.0, 255.0));
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get_color(dst, blue_t()) = static_cast<dst_channel_t>(
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detail::clamp(1.6438 * ( y - 16.0 ) - 2.0172 * ( cb -128.0 ), 0.0, 255.0));
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}
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};
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/*
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* Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.601_conversion
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* digital Y'CbCr derived from digital R'dG'dB'd 8 bits per sample, each using the full range.
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* with NO footroom wither headroom.
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*/
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/**
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* @brief Convert RGB to YCbCr ITU.BT-601.
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*/
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template<>
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struct default_color_converter_impl<rgb_t, ycbcr_601__t>
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{
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template < typename SRCP, typename DSTP >
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void operator()( const SRCP& src, DSTP& dst ) const
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{
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using namespace ycbcr_601_color_space;
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using src_channel_t = typename channel_type<SRCP>::type;
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using dst_channel_t = typename channel_type<DSTP>::type;
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src_channel_t red = channel_convert<src_channel_t>( get_color(src, red_t()));
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src_channel_t green = channel_convert<src_channel_t>( get_color(src, green_t()));
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src_channel_t blue = channel_convert<src_channel_t>( get_color(src, blue_t()));
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double y = 16.0 + 0.2567 * red + 0.5041 * green + 0.0979 * blue;
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double cb = 128.0 - 0.1482 * red - 0.2909 * green + 0.4392 * blue;
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double cr = 128.0 + 0.4392 * red - 0.3677 * green - 0.0714 * blue;
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get_color( dst, y_t() ) = (dst_channel_t) y;
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get_color( dst, cb_t() ) = (dst_channel_t) cb;
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get_color( dst, cr_t() ) = (dst_channel_t) cr;
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}
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};
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/**
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* @brief Convert RGB to YCbCr ITU.BT-709.
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*/
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template<>
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struct default_color_converter_impl<rgb_t, ycbcr_709__t>
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{
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template < typename SRCP, typename DSTP >
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void operator()( const SRCP& src, DSTP& dst ) const
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{
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using namespace ycbcr_709_color_space;
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using src_channel_t = typename channel_type<SRCP>::type;
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using dst_channel_t = typename channel_type<DSTP>::type;
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src_channel_t red = channel_convert<src_channel_t>( get_color(src, red_t()));
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src_channel_t green = channel_convert<src_channel_t>( get_color(src, green_t()));
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src_channel_t blue = channel_convert<src_channel_t>( get_color(src, blue_t()));
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double y = 0.299 * red + 0.587 * green + 0.114 * blue;
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double cb = 128.0 - 0.168736 * red - 0.331264 * green + 0.5 * blue;
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double cr = 128.0 + 0.5 * red - 0.418688 * green - 0.081312 * blue;
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get_color( dst, y_t() ) = (dst_channel_t) y;
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get_color( dst, cb_t() ) = (dst_channel_t) cb;
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get_color( dst, cr_t() ) = (dst_channel_t) cr;
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}
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};
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/**
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* @brief Convert RGB to YCbCr ITU.BT-709.
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*/
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template<>
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struct default_color_converter_impl<ycbcr_709__t, rgb_t>
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{
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template < typename SRCP, typename DSTP >
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void operator()( const SRCP& src, DSTP& dst ) const
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{
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using namespace ycbcr_709_color_space;
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using src_channel_t = typename channel_type<SRCP>::type;
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using dst_channel_t = typename channel_type<DSTP>::type;
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src_channel_t y = channel_convert<src_channel_t>( get_color(src, y_t()) );
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src_channel_t cb_clipped = channel_convert<src_channel_t>( get_color(src, cb_t()) - 128 );
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src_channel_t cr_clipped = channel_convert<src_channel_t>( get_color(src, cr_t()) - 128 );
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double red = y + 1.042 * cr_clipped;
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double green = y - 0.34414 * cb_clipped - 0.71414 * cr_clipped;
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double blue = y + 1.772 * cb_clipped;
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get_color( dst, red_t() ) = (dst_channel_t) red;
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get_color( dst, green_t() ) = (dst_channel_t) green;
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get_color( dst, blue_t() ) = (dst_channel_t) blue;
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}
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};
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} // namespace gil
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} // namespace boost
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#endif
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