//
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// Copyright 2005-2007 Adobe Systems Incorporated
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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_COLOR_CONVERT_HPP
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#define BOOST_GIL_COLOR_CONVERT_HPP
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#include <boost/gil/channel_algorithm.hpp>
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#include <boost/gil/cmyk.hpp>
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#include <boost/gil/color_base_algorithm.hpp>
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#include <boost/gil/gray.hpp>
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#include <boost/gil/metafunctions.hpp>
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#include <boost/gil/pixel.hpp>
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#include <boost/gil/rgb.hpp>
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#include <boost/gil/rgba.hpp>
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#include <boost/gil/utilities.hpp>
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#include <algorithm>
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#include <functional>
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#include <type_traits>
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namespace boost { namespace gil {
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/// Support for fast and simple color conversion.
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/// Accurate color conversion using color profiles can be supplied separately in a dedicated module.
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// Forward-declare
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template <typename P> struct channel_type;
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////////////////////////////////////////////////////////////////////////////////////////
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///
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/// COLOR SPACE CONVERSION
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///
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////////////////////////////////////////////////////////////////////////////////////////
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/// \ingroup ColorConvert
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/// \brief Color Convertion function object. To be specialized for every src/dst color space
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template <typename C1, typename C2>
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struct default_color_converter_impl
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{
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static_assert(
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std::is_same<C1, C2>::value,
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"default_color_converter_impl not specialized for given color spaces");
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};
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/// \ingroup ColorConvert
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/// \brief When the color space is the same, color convertion performs channel depth conversion
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template <typename C>
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struct default_color_converter_impl<C,C> {
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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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static_for_each(src,dst,default_channel_converter());
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}
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};
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namespace detail {
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/// red * .3 + green * .59 + blue * .11 + .5
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// The default implementation of to_luminance uses float0..1 as the intermediate channel type
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template <typename RedChannel, typename GreenChannel, typename BlueChannel, typename GrayChannelValue>
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struct rgb_to_luminance_fn {
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GrayChannelValue operator()(const RedChannel& red, const GreenChannel& green, const BlueChannel& blue) const {
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return channel_convert<GrayChannelValue>(float32_t(
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channel_convert<float32_t>(red )*0.30f +
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channel_convert<float32_t>(green)*0.59f +
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channel_convert<float32_t>(blue )*0.11f) );
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}
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};
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// performance specialization for unsigned char
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template <typename GrayChannelValue>
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struct rgb_to_luminance_fn<uint8_t,uint8_t,uint8_t, GrayChannelValue> {
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GrayChannelValue operator()(uint8_t red, uint8_t green, uint8_t blue) const {
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return channel_convert<GrayChannelValue>(uint8_t(
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((uint32_t(red )*4915 + uint32_t(green)*9667 + uint32_t(blue )*1802) + 8192) >> 14));
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}
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};
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template <typename GrayChannel, typename RedChannel, typename GreenChannel, typename BlueChannel>
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typename channel_traits<GrayChannel>::value_type rgb_to_luminance(const RedChannel& red, const GreenChannel& green, const BlueChannel& blue) {
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return rgb_to_luminance_fn<RedChannel,GreenChannel,BlueChannel,
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typename channel_traits<GrayChannel>::value_type>()(red,green,blue);
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}
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} // namespace detail
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/// \ingroup ColorConvert
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/// \brief Gray to RGB
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template <>
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struct default_color_converter_impl<gray_t,rgb_t> {
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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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get_color(dst,red_t()) =
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channel_convert<typename color_element_type<P2, red_t >::type>(get_color(src,gray_color_t()));
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get_color(dst,green_t())=
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channel_convert<typename color_element_type<P2, green_t>::type>(get_color(src,gray_color_t()));
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get_color(dst,blue_t()) =
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channel_convert<typename color_element_type<P2, blue_t >::type>(get_color(src,gray_color_t()));
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}
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};
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/// \ingroup ColorConvert
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/// \brief Gray to CMYK
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/// \todo FIXME: Where does this calculation come from? Shouldn't gray be inverted?
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/// Currently, white becomes black and black becomes white.
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template <>
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struct default_color_converter_impl<gray_t,cmyk_t> {
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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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get_color(dst,cyan_t())=
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channel_traits<typename color_element_type<P2, cyan_t >::type>::min_value();
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get_color(dst,magenta_t())=
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channel_traits<typename color_element_type<P2, magenta_t>::type>::min_value();
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get_color(dst,yellow_t())=
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channel_traits<typename color_element_type<P2, yellow_t >::type>::min_value();
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get_color(dst,black_t())=
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channel_convert<typename color_element_type<P2, black_t >::type>(get_color(src,gray_color_t()));
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}
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};
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/// \ingroup ColorConvert
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/// \brief RGB to Gray
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template <>
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struct default_color_converter_impl<rgb_t,gray_t> {
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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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get_color(dst,gray_color_t()) =
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detail::rgb_to_luminance<typename color_element_type<P2,gray_color_t>::type>(
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get_color(src,red_t()), get_color(src,green_t()), get_color(src,blue_t())
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);
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}
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};
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/// \ingroup ColorConvert
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/// \brief RGB to CMYK (not the fastest code in the world)
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///
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/// k = min(1 - r, 1 - g, 1 - b)
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/// c = (1 - r - k) / (1 - k)
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/// m = (1 - g - k) / (1 - k)
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/// y = (1 - b - k) / (1 - k)
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/// where `1` denotes max value of channel type of destination pixel.
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///
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/// The conversion from RGB to CMYK is based on CMY->CMYK (Version 2)
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/// from the Principles of Digital Image Processing - Fundamental Techniques
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/// by Burger, Wilhelm, Burge, Mark J.
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/// and it is a gross approximation not precise enough for professional work.
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///
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/// \todo FIXME: The original implementation did not handle properly signed CMYK pixels as destination
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///
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template <>
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struct default_color_converter_impl<rgb_t, cmyk_t>
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{
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template <typename SrcPixel, typename DstPixel>
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void operator()(SrcPixel const& src, DstPixel& dst) const
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{
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using src_t = typename channel_type<SrcPixel>::type;
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src_t const r = get_color(src, red_t());
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src_t const g = get_color(src, green_t());
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src_t const b = get_color(src, blue_t());
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using dst_t = typename channel_type<DstPixel>::type;
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dst_t const c = channel_invert(channel_convert<dst_t>(r)); // c = 1 - r
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dst_t const m = channel_invert(channel_convert<dst_t>(g)); // m = 1 - g
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dst_t const y = channel_invert(channel_convert<dst_t>(b)); // y = 1 - b
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dst_t const k = (std::min)(c, (std::min)(m, y)); // k = minimum(c, m, y)
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// Apply color correction, strengthening, reducing non-zero components by
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// s = 1 / (1 - k) for k < 1, where 1 denotes dst_t max, otherwise s = 1 (literal).
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dst_t const dst_max = channel_traits<dst_t>::max_value();
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dst_t const s_div = dst_max - k;
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if (s_div != 0)
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{
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double const s = dst_max / static_cast<double>(s_div);
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get_color(dst, cyan_t()) = static_cast<dst_t>((c - k) * s);
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get_color(dst, magenta_t()) = static_cast<dst_t>((m - k) * s);
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get_color(dst, yellow_t()) = static_cast<dst_t>((y - k) * s);
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}
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else
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{
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// Black only for k = 1 (max of dst_t)
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get_color(dst, cyan_t()) = channel_traits<dst_t>::min_value();
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get_color(dst, magenta_t()) = channel_traits<dst_t>::min_value();
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get_color(dst, yellow_t()) = channel_traits<dst_t>::min_value();
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}
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get_color(dst, black_t()) = k;
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}
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};
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/// \ingroup ColorConvert
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/// \brief CMYK to RGB (not the fastest code in the world)
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///
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/// r = 1 - min(1, c*(1-k)+k)
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/// g = 1 - min(1, m*(1-k)+k)
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/// b = 1 - min(1, y*(1-k)+k)
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template <>
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struct default_color_converter_impl<cmyk_t,rgb_t> {
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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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using T1 = typename channel_type<P1>::type;
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get_color(dst,red_t()) =
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channel_convert<typename color_element_type<P2,red_t>::type>(
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channel_invert<T1>(
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(std::min)(channel_traits<T1>::max_value(),
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T1(channel_multiply(get_color(src,cyan_t()),channel_invert(get_color(src,black_t())))+get_color(src,black_t())))));
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get_color(dst,green_t())=
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channel_convert<typename color_element_type<P2,green_t>::type>(
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channel_invert<T1>(
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(std::min)(channel_traits<T1>::max_value(),
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T1(channel_multiply(get_color(src,magenta_t()),channel_invert(get_color(src,black_t())))+get_color(src,black_t())))));
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get_color(dst,blue_t()) =
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channel_convert<typename color_element_type<P2,blue_t>::type>(
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channel_invert<T1>(
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(std::min)(channel_traits<T1>::max_value(),
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T1(channel_multiply(get_color(src,yellow_t()),channel_invert(get_color(src,black_t())))+get_color(src,black_t())))));
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}
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};
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/// \ingroup ColorConvert
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/// \brief CMYK to Gray
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///
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/// gray = (1 - 0.212c - 0.715m - 0.0722y) * (1 - k)
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template <>
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struct default_color_converter_impl<cmyk_t,gray_t> {
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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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get_color(dst,gray_color_t())=
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channel_convert<typename color_element_type<P2,gray_color_t>::type>(
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channel_multiply(
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channel_invert(
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detail::rgb_to_luminance<typename color_element_type<P1,black_t>::type>(
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get_color(src,cyan_t()),
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get_color(src,magenta_t()),
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get_color(src,yellow_t())
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)
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),
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channel_invert(get_color(src,black_t()))));
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}
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};
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namespace detail {
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template <typename Pixel>
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auto alpha_or_max_impl(Pixel const& p, std::true_type) -> typename channel_type<Pixel>::type
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{
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return get_color(p,alpha_t());
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}
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template <typename Pixel>
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auto alpha_or_max_impl(Pixel const&, std::false_type) -> typename channel_type<Pixel>::type
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{
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return channel_traits<typename channel_type<Pixel>::type>::max_value();
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}
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} // namespace detail
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// Returns max_value if the pixel has no alpha channel. Otherwise returns the alpha.
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template <typename Pixel>
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auto alpha_or_max(Pixel const& p) -> typename channel_type<Pixel>::type
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{
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return detail::alpha_or_max_impl(
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p,
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mp11::mp_contains<typename color_space_type<Pixel>::type, alpha_t>());
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}
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/// \ingroup ColorConvert
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/// \brief Converting any pixel type to RGBA. Note: Supports homogeneous pixels only.
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template <typename C1>
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struct default_color_converter_impl<C1,rgba_t> {
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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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using T2 = typename channel_type<P2>::type;
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pixel<T2,rgb_layout_t> tmp;
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default_color_converter_impl<C1,rgb_t>()(src,tmp);
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get_color(dst,red_t()) =get_color(tmp,red_t());
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get_color(dst,green_t())=get_color(tmp,green_t());
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get_color(dst,blue_t()) =get_color(tmp,blue_t());
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get_color(dst,alpha_t())=channel_convert<T2>(alpha_or_max(src));
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}
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};
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/// \ingroup ColorConvert
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/// \brief Converting RGBA to any pixel type. Note: Supports homogeneous pixels only.
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///
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/// Done by multiplying the alpha to get to RGB, then converting the RGB to the target pixel type
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/// Note: This may be slower if the compiler doesn't optimize out constructing/destructing a temporary RGB pixel.
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/// Consider rewriting if performance is an issue
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template <typename C2>
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struct default_color_converter_impl<rgba_t,C2> {
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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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using T1 = typename channel_type<P1>::type;
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default_color_converter_impl<rgb_t,C2>()(
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pixel<T1,rgb_layout_t>(channel_multiply(get_color(src,red_t()), get_color(src,alpha_t())),
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channel_multiply(get_color(src,green_t()),get_color(src,alpha_t())),
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channel_multiply(get_color(src,blue_t()), get_color(src,alpha_t())))
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,dst);
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}
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};
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/// \ingroup ColorConvert
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/// \brief Unfortunately RGBA to RGBA must be explicitly provided - otherwise we get ambiguous specialization error.
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template <>
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struct default_color_converter_impl<rgba_t,rgba_t> {
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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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static_for_each(src,dst,default_channel_converter());
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}
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};
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/// @defgroup ColorConvert Color Space Converion
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/// \ingroup ColorSpaces
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/// \brief Support for conversion between pixels of different color spaces and channel depths
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/// \ingroup PixelAlgorithm ColorConvert
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/// \brief class for color-converting one pixel to another
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struct default_color_converter {
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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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using SrcColorSpace = typename color_space_type<SrcP>::type;
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using DstColorSpace = typename color_space_type<DstP>::type;
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default_color_converter_impl<SrcColorSpace,DstColorSpace>()(src,dst);
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}
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};
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/// \ingroup PixelAlgorithm
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/// \brief helper function for converting one pixel to another using GIL default color-converters
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/// where ScrP models HomogeneousPixelConcept
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/// DstP models HomogeneousPixelValueConcept
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template <typename SrcP, typename DstP>
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inline void color_convert(const SrcP& src, DstP& dst) {
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default_color_converter()(src,dst);
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}
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} } // namespace boost::gil
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#endif
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