//
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// Copyright 2012 Chung-Lin Wen
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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_LAB_HPP
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#define BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_LAB_HPP
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#include <boost/gil/extension/toolbox/color_spaces/xyz.hpp>
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#include <boost/gil/color_convert.hpp>
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#include <boost/gil.hpp> // FIXME: Include what you use, not everything, even in extensions!
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#include <boost/gil/detail/mp11.hpp>
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namespace boost{ namespace gil {
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/// \addtogroup ColorNameModel
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/// \{
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namespace lab_color_space
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{
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/// \brief Luminance
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struct luminance_t {};
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/// \brief a Color Component
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struct a_color_opponent_t {};
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/// \brief b Color Component
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struct b_color_opponent_t {};
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}
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/// \}
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/// \ingroup ColorSpaceModel
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using lab_t = mp11::mp_list
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<
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lab_color_space::luminance_t,
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lab_color_space::a_color_opponent_t,
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lab_color_space::b_color_opponent_t
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>;
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/// \ingroup LayoutModel
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using lab_layout_t = layout<lab_t>;
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BOOST_GIL_DEFINE_ALL_TYPEDEFS(32f, float32_t, lab)
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/// \ingroup ColorConvert
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/// \brief LAB to XYZ
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template <>
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struct default_color_converter_impl< lab_t, xyz_t >
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{
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template <typename P1, typename P2>
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void operator()( const P1& src, P2& dst ) const
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{
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using namespace lab_color_space;
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using namespace xyz_color_space;
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float32_t p = ((get_color(src, luminance_t()) + 16.f)/116.f);
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get_color(dst, y_t()) =
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1.f * powf(p, 3.f);
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get_color(dst, x_t()) =
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0.95047f * powf((p +
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(get_color(src, a_color_opponent_t())/500.f)
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), 3.f);
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get_color(dst, z_t()) =
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1.08883f * powf((p -
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(get_color(src, b_color_opponent_t())/200.f)
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), 3.f);
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}
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};
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/// \ingroup ColorConvert
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/// \brief XYZ to LAB
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/// \note I assume \c xyz_t
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template <>
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struct default_color_converter_impl< xyz_t, lab_t >
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{
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private:
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/// \ref http://www.brucelindbloom.com/index.html?Eqn_XYZ_to_Lab.html
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BOOST_FORCEINLINE
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float32_t forward_companding(float32_t value) const
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{
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if (value > 216.f/24389.f)
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{
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return powf(value, 1.f/3.f);
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}
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else
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{
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return ((24389.f/27.f * value + 16.f)/116.f);
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}
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}
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public:
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template <typename P1, typename P2>
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void operator()( const P1& src, P2& dst ) const
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{
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using namespace lab_color_space;
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float32_t f_y =
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forward_companding(
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channel_convert<float32_t>(
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get_color(src, xyz_color_space::y_t())
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)
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// / 1.f
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);
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float32_t f_x =
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forward_companding(
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channel_convert<float32_t>(
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get_color(src, xyz_color_space::x_t())
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)
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* (1.f / 0.95047f) // if the compiler is smart, it should
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// precalculate this, no?
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);
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float32_t f_z =
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forward_companding(
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channel_convert<float32_t>(
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get_color(src, xyz_color_space::z_t())
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)
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* (1.f / 1.08883f) // if the compiler is smart, it should
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// precalculate this, no?
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);
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get_color(dst, luminance_t()) =
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116.f * f_y - 16.f;
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get_color(dst, a_color_opponent_t()) =
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500.f * (f_x - f_y);
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get_color(dst, b_color_opponent_t()) =
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200.f * (f_y - f_z);
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}
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};
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/// \ingroup ColorConvert
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/// \brief RGB to LAB
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template <>
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struct default_color_converter_impl< rgb_t, lab_t >
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{
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template <typename P1, typename P2>
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void operator()( const P1& src, P2& dst ) const
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{
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using namespace lab_color_space;
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xyz32f_pixel_t xyz32f_temp_pixel;
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default_color_converter_impl<rgb_t, xyz_t>()(src, xyz32f_temp_pixel);
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default_color_converter_impl<xyz_t, lab_t>()(xyz32f_temp_pixel, dst);
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}
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};
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/// \ingroup ColorConvert
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/// \brief LAB to RGB
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template <>
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struct default_color_converter_impl<lab_t,rgb_t>
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{
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template <typename P1, typename P2>
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void operator()( const P1& src, P2& dst) const
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{
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using namespace lab_color_space;
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xyz32f_pixel_t xyz32f_temp_pixel;
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default_color_converter_impl<lab_t, xyz_t>()(src, xyz32f_temp_pixel);
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default_color_converter_impl<xyz_t, rgb_t>()(xyz32f_temp_pixel, dst);
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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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