2 // Copyright 2013 Juan V. Puertos G-Cluster, Christian Henning
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
8 #ifndef BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_YCBCR_HPP
9 #define BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_YCBCR_HPP
11 #include <boost/gil/extension/toolbox/metafunctions/get_num_bits.hpp>
13 #include <boost/gil/color_convert.hpp>
14 #include <boost/gil.hpp> // FIXME: Include what you use!
15 #include <boost/gil/detail/mp11.hpp>
17 #include <boost/config.hpp>
20 #include <type_traits>
22 namespace boost { namespace gil {
24 /// \addtogroup ColorNameModel
26 namespace ycbcr_601_color_space
30 /// \brief Blue chrominance component
32 /// \brief Red chrominance component
36 namespace ycbcr_709_color_space
40 /// \brief Blue chrominance component
42 /// \brief Red chrominance component
47 /// \ingroup ColorSpaceModel
48 using ycbcr_601__t = mp11::mp_list
50 ycbcr_601_color_space::y_t,
51 ycbcr_601_color_space::cb_t,
52 ycbcr_601_color_space::cr_t
55 /// \ingroup ColorSpaceModel
56 using ycbcr_709__t = mp11::mp_list
58 ycbcr_709_color_space::y_t,
59 ycbcr_709_color_space::cb_t,
60 ycbcr_709_color_space::cr_t
63 /// \ingroup LayoutModel
64 using ycbcr_601__layout_t = boost::gil::layout<ycbcr_601__t>;
65 using ycbcr_709__layout_t = boost::gil::layout<ycbcr_709__t>;
67 //The channel depth is ALWAYS 8bits ofr YCbCr!
68 GIL_DEFINE_ALL_TYPEDEFS(8, uint8_t, ycbcr_601_)
69 GIL_DEFINE_ALL_TYPEDEFS(8, uint8_t, ycbcr_709_)
73 // Source:boost/algorithm/clamp.hpp
78 typename boost::mp11::mp_identity<T>::type const & lo,
79 typename boost::mp11::mp_identity<T>::type const & hi)
81 // assert ( !p ( hi, lo )); // Can't assert p ( lo, hi ) b/c they might be equal
82 auto const p = std::less<T>();
83 return p(val, lo) ? lo : p(hi, val) ? hi : val;
89 * 601 Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.601_conversion
90 * 709 Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.709_conversion
91 * (using values coming directly from ITU-R BT.601 recommendation)
92 * (using values coming directly from ITU-R BT.709 recommendation)
96 * @brief Convert YCbCr ITU.BT-601 to RGB.
99 struct default_color_converter_impl<ycbcr_601__t, rgb_t>
101 // 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.
102 template < typename SRCP, typename DSTP >
103 void operator()( const SRCP& src, DSTP& dst ) const
105 using dst_channel_t = typename channel_type<DSTP>::type;
106 convert(src, dst, typename std::is_same
108 std::integral_constant<int, sizeof(dst_channel_t)>,
109 std::integral_constant<int, 1>
115 // optimization for bit8 channels
116 template< typename Src_Pixel
119 void convert( const Src_Pixel& src
121 , std::true_type // is 8 bit channel
124 using namespace ycbcr_601_color_space;
126 using src_channel_t = typename channel_type<Src_Pixel>::type;
127 using dst_channel_t = typename channel_type<Dst_Pixel>::type;
129 src_channel_t y = channel_convert<src_channel_t>( get_color(src, y_t()));
130 src_channel_t cb = channel_convert<src_channel_t>( get_color(src, cb_t()));
131 src_channel_t cr = channel_convert<src_channel_t>( get_color(src, cr_t()));
133 // The intermediate results of the formulas require at least 16bits of precission.
134 std::int_fast16_t c = y - 16;
135 std::int_fast16_t d = cb - 128;
136 std::int_fast16_t e = cr - 128;
137 std::int_fast16_t red = detail::clamp((( 298 * c + 409 * e + 128) >> 8), 0, 255);
138 std::int_fast16_t green = detail::clamp((( 298 * c - 100 * d - 208 * e + 128) >> 8), 0, 255);
139 std::int_fast16_t blue = detail::clamp((( 298 * c + 516 * d + 128) >> 8), 0, 255);
141 get_color( dst, red_t() ) = (dst_channel_t) red;
142 get_color( dst, green_t() ) = (dst_channel_t) green;
143 get_color( dst, blue_t() ) = (dst_channel_t) blue;
147 template< typename Src_Pixel
150 void convert( const Src_Pixel& src
152 , std::false_type // is 8 bit channel
155 using namespace ycbcr_601_color_space;
157 using dst_channel_t = typename channel_type<Dst_Pixel>::type;
159 double y = get_color( src, y_t() );
160 double cb = get_color( src, cb_t() );
161 double cr = get_color( src, cr_t() );
163 get_color(dst, red_t()) = static_cast<dst_channel_t>(
164 detail::clamp(1.6438 * (y - 16.0) + 1.5960 * (cr -128.0), 0.0, 255.0));
166 get_color(dst, green_t()) = static_cast<dst_channel_t>(
167 detail::clamp(1.6438 * (y - 16.0) - 0.3917 * (cb - 128.0) + 0.8129 * (cr -128.0), 0.0, 255.0));
169 get_color(dst, blue_t()) = static_cast<dst_channel_t>(
170 detail::clamp(1.6438 * ( y - 16.0 ) - 2.0172 * ( cb -128.0 ), 0.0, 255.0));
175 * Source: http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.601_conversion
176 * digital Y'CbCr derived from digital R'dG'dB'd 8 bits per sample, each using the full range.
177 * with NO footroom wither headroom.
180 * @brief Convert RGB to YCbCr ITU.BT-601.
183 struct default_color_converter_impl<rgb_t, ycbcr_601__t>
185 template < typename SRCP, typename DSTP >
186 void operator()( const SRCP& src, DSTP& dst ) const
188 using namespace ycbcr_601_color_space;
190 using src_channel_t = typename channel_type<SRCP>::type;
191 using dst_channel_t = typename channel_type<DSTP>::type;
193 src_channel_t red = channel_convert<src_channel_t>( get_color(src, red_t()));
194 src_channel_t green = channel_convert<src_channel_t>( get_color(src, green_t()));
195 src_channel_t blue = channel_convert<src_channel_t>( get_color(src, blue_t()));
197 double y = 16.0 + 0.2567 * red + 0.5041 * green + 0.0979 * blue;
198 double cb = 128.0 - 0.1482 * red - 0.2909 * green + 0.4392 * blue;
199 double cr = 128.0 + 0.4392 * red - 0.3677 * green - 0.0714 * blue;
201 get_color( dst, y_t() ) = (dst_channel_t) y;
202 get_color( dst, cb_t() ) = (dst_channel_t) cb;
203 get_color( dst, cr_t() ) = (dst_channel_t) cr;
208 * @brief Convert RGB to YCbCr ITU.BT-709.
211 struct default_color_converter_impl<rgb_t, ycbcr_709__t>
213 template < typename SRCP, typename DSTP >
214 void operator()( const SRCP& src, DSTP& dst ) const
216 using namespace ycbcr_709_color_space;
218 using src_channel_t = typename channel_type<SRCP>::type;
219 using dst_channel_t = typename channel_type<DSTP>::type;
221 src_channel_t red = channel_convert<src_channel_t>( get_color(src, red_t()));
222 src_channel_t green = channel_convert<src_channel_t>( get_color(src, green_t()));
223 src_channel_t blue = channel_convert<src_channel_t>( get_color(src, blue_t()));
225 double y = 0.299 * red + 0.587 * green + 0.114 * blue;
226 double cb = 128.0 - 0.168736 * red - 0.331264 * green + 0.5 * blue;
227 double cr = 128.0 + 0.5 * red - 0.418688 * green - 0.081312 * blue;
229 get_color( dst, y_t() ) = (dst_channel_t) y;
230 get_color( dst, cb_t() ) = (dst_channel_t) cb;
231 get_color( dst, cr_t() ) = (dst_channel_t) cr;
236 * @brief Convert RGB to YCbCr ITU.BT-709.
239 struct default_color_converter_impl<ycbcr_709__t, rgb_t>
241 template < typename SRCP, typename DSTP >
242 void operator()( const SRCP& src, DSTP& dst ) const
244 using namespace ycbcr_709_color_space;
246 using src_channel_t = typename channel_type<SRCP>::type;
247 using dst_channel_t = typename channel_type<DSTP>::type;
249 src_channel_t y = channel_convert<src_channel_t>( get_color(src, y_t()) );
250 src_channel_t cb_clipped = channel_convert<src_channel_t>( get_color(src, cb_t()) - 128 );
251 src_channel_t cr_clipped = channel_convert<src_channel_t>( get_color(src, cr_t()) - 128 );
253 double red = y + 1.042 * cr_clipped;
254 double green = y - 0.34414 * cb_clipped - 0.71414 * cr_clipped;
255 double blue = y + 1.772 * cb_clipped;
257 get_color( dst, red_t() ) = (dst_channel_t) red;
258 get_color( dst, green_t() ) = (dst_channel_t) green;
259 get_color( dst, blue_t() ) = (dst_channel_t) blue;