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//
// Copyright 2013 Juan V. Puertos G-Cluster, Christian Henning
//
// Distributed under 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_SPACES_YCBCR_HPP
#define BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_YCBCR_HPP
#include <boost/gil/extension/toolbox/metafunctions/get_num_bits.hpp>
#include <boost/gil/color_convert.hpp>
#include <boost/gil.hpp> // FIXME: Include what you use!
#include <boost/config.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/mpl/range_c.hpp>
#include <boost/mpl/vector_c.hpp>
#include <cstdint>
#include <type_traits>
namespace boost{ namespace gil {
/// \addtogroup ColorNameModel
/// \{
namespace ycbcr_601_color_space
{
/// \brief Luminance
struct y_t {};
/// \brief Blue chrominance component
struct cb_t {};
/// \brief Red chrominance component
struct cr_t {};
}
namespace ycbcr_709_color_space
{
/// \brief Luminance
struct y_t {};
/// \brief Blue chrominance component
struct cb_t {};
/// \brief Red chrominance component
struct cr_t {};
}
/// \}
/// \ingroup ColorSpaceModel
using ycbcr_601__t = boost::mpl::vector3
<
ycbcr_601_color_space::y_t,
ycbcr_601_color_space::cb_t,
ycbcr_601_color_space::cr_t>
;
/// \ingroup ColorSpaceModel
using ycbcr_709__t = boost::mpl::vector3
<
ycbcr_709_color_space::y_t,
ycbcr_709_color_space::cb_t,
ycbcr_709_color_space::cr_t
>;
/// \ingroup LayoutModel
using ycbcr_601__layout_t = boost::gil::layout<ycbcr_601__t>;
using ycbcr_709__layout_t = boost::gil::layout<ycbcr_709__t>;
//The channel depth is ALWAYS 8bits ofr YCbCr!
GIL_DEFINE_ALL_TYPEDEFS(8, uint8_t, ycbcr_601_)
GIL_DEFINE_ALL_TYPEDEFS(8, uint8_t, ycbcr_709_)
namespace detail {
// Source:boost/algorithm/clamp.hpp
template<typename T>
BOOST_CXX14_CONSTEXPR T const& clamp(T const& val,
typename boost::mpl::identity<T>::type const & lo,
typename boost::mpl::identity<T>::type const & hi)
{
// assert ( !p ( hi, lo )); // Can't assert p ( lo, hi ) b/c they might be equal
auto const p = std::less<T>();
return p(val, lo) ? lo : p(hi, val) ? hi : val;
}
} // namespace detail
/*
* 601 Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.601_conversion
* 709 Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.709_conversion
* (using values coming directly from ITU-R BT.601 recommendation)
* (using values coming directly from ITU-R BT.709 recommendation)
*/
/**
* @brief Convert YCbCr ITU.BT-601 to RGB.
*/
template<>
struct default_color_converter_impl<ycbcr_601__t, rgb_t>
{
// 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.
template < typename SRCP, typename DSTP >
void operator()( const SRCP& src, DSTP& dst ) const
{
using dst_channel_t = typename channel_type<DSTP>::type;
convert(src, dst, typename std::is_same
<
typename mpl::int_<sizeof(dst_channel_t)>::type,
typename mpl::int_<1>::type
>::type());
}
private:
// optimization for bit8 channels
template< typename Src_Pixel
, typename Dst_Pixel
>
void convert( const Src_Pixel& src
, Dst_Pixel& dst
, mpl::true_ // is 8 bit channel
) const
{
using namespace ycbcr_601_color_space;
using src_channel_t = typename channel_type<Src_Pixel>::type;
using dst_channel_t = typename channel_type<Dst_Pixel>::type;
src_channel_t y = channel_convert<src_channel_t>( get_color(src, y_t()));
src_channel_t cb = channel_convert<src_channel_t>( get_color(src, cb_t()));
src_channel_t cr = channel_convert<src_channel_t>( get_color(src, cr_t()));
// The intermediate results of the formulas require at least 16bits of precission.
std::int_fast16_t c = y - 16;
std::int_fast16_t d = cb - 128;
std::int_fast16_t e = cr - 128;
std::int_fast16_t red = detail::clamp((( 298 * c + 409 * e + 128) >> 8), 0, 255);
std::int_fast16_t green = detail::clamp((( 298 * c - 100 * d - 208 * e + 128) >> 8), 0, 255);
std::int_fast16_t blue = detail::clamp((( 298 * c + 516 * d + 128) >> 8), 0, 255);
get_color( dst, red_t() ) = (dst_channel_t) red;
get_color( dst, green_t() ) = (dst_channel_t) green;
get_color( dst, blue_t() ) = (dst_channel_t) blue;
}
template< typename Src_Pixel
, typename Dst_Pixel
>
void convert( const Src_Pixel& src
, Dst_Pixel& dst
, mpl::false_ // is 8 bit channel
) const
{
using namespace ycbcr_601_color_space;
using dst_channel_t = typename channel_type<Dst_Pixel>::type;
double y = get_color( src, y_t() );
double cb = get_color( src, cb_t() );
double cr = get_color( src, cr_t() );
get_color(dst, red_t()) = static_cast<dst_channel_t>(
detail::clamp(1.6438 * (y - 16.0) + 1.5960 * (cr -128.0), 0.0, 255.0));
get_color(dst, green_t()) = static_cast<dst_channel_t>(
detail::clamp(1.6438 * (y - 16.0) - 0.3917 * (cb - 128.0) + 0.8129 * (cr -128.0), 0.0, 255.0));
get_color(dst, blue_t()) = static_cast<dst_channel_t>(
detail::clamp(1.6438 * ( y - 16.0 ) - 2.0172 * ( cb -128.0 ), 0.0, 255.0));
}
};
/*
* Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.601_conversion
* digital Y'CbCr derived from digital R'dG'dB'd 8 bits per sample, each using the full range.
* with NO footroom wither headroom.
*/
/**
* @brief Convert RGB to YCbCr ITU.BT-601.
*/
template<>
struct default_color_converter_impl<rgb_t, ycbcr_601__t>
{
template < typename SRCP, typename DSTP >
void operator()( const SRCP& src, DSTP& dst ) const
{
using namespace ycbcr_601_color_space;
using src_channel_t = typename channel_type<SRCP>::type;
using dst_channel_t = typename channel_type<DSTP>::type;
src_channel_t red = channel_convert<src_channel_t>( get_color(src, red_t()));
src_channel_t green = channel_convert<src_channel_t>( get_color(src, green_t()));
src_channel_t blue = channel_convert<src_channel_t>( get_color(src, blue_t()));
double y = 16.0 + 0.2567 * red + 0.5041 * green + 0.0979 * blue;
double cb = 128.0 - 0.1482 * red - 0.2909 * green + 0.4392 * blue;
double cr = 128.0 + 0.4392 * red - 0.3677 * green - 0.0714 * blue;
get_color( dst, y_t() ) = (dst_channel_t) y;
get_color( dst, cb_t() ) = (dst_channel_t) cb;
get_color( dst, cr_t() ) = (dst_channel_t) cr;
}
};
/**
* @brief Convert RGB to YCbCr ITU.BT-709.
*/
template<>
struct default_color_converter_impl<rgb_t, ycbcr_709__t>
{
template < typename SRCP, typename DSTP >
void operator()( const SRCP& src, DSTP& dst ) const
{
using namespace ycbcr_709_color_space;
using src_channel_t = typename channel_type<SRCP>::type;
using dst_channel_t = typename channel_type<DSTP>::type;
src_channel_t red = channel_convert<src_channel_t>( get_color(src, red_t()));
src_channel_t green = channel_convert<src_channel_t>( get_color(src, green_t()));
src_channel_t blue = channel_convert<src_channel_t>( get_color(src, blue_t()));
double y = 0.299 * red + 0.587 * green + 0.114 * blue;
double cb = 128.0 - 0.168736 * red - 0.331264 * green + 0.5 * blue;
double cr = 128.0 + 0.5 * red - 0.418688 * green - 0.081312 * blue;
get_color( dst, y_t() ) = (dst_channel_t) y;
get_color( dst, cb_t() ) = (dst_channel_t) cb;
get_color( dst, cr_t() ) = (dst_channel_t) cr;
}
};
/**
* @brief Convert RGB to YCbCr ITU.BT-709.
*/
template<>
struct default_color_converter_impl<ycbcr_709__t, rgb_t>
{
template < typename SRCP, typename DSTP >
void operator()( const SRCP& src, DSTP& dst ) const
{
using namespace ycbcr_709_color_space;
using src_channel_t = typename channel_type<SRCP>::type;
using dst_channel_t = typename channel_type<DSTP>::type;
src_channel_t y = channel_convert<src_channel_t>( get_color(src, y_t()) );
src_channel_t cb_clipped = channel_convert<src_channel_t>( get_color(src, cb_t()) - 128 );
src_channel_t cr_clipped = channel_convert<src_channel_t>( get_color(src, cr_t()) - 128 );
double red = y + 1.042 * cr_clipped;
double green = y - 0.34414 * cb_clipped - 0.71414 * cr_clipped;
double blue = y + 1.772 * cb_clipped;
get_color( dst, red_t() ) = (dst_channel_t) red;
get_color( dst, green_t() ) = (dst_channel_t) green;
get_color( dst, blue_t() ) = (dst_channel_t) blue;
}
};
} // namespace gil
} // namespace boost
#endif
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