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Fix conversion from RGB to signed CMYK #522

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merged 6 commits into from
Oct 10, 2020
Merged

Fix conversion from RGB to signed CMYK #522

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01d9599
Fix conversion of rgb to signed cmyk(boostorg#479)
harshitpant1 Oct 8, 2020
3f54d00
changed naming of dst_us_t to uint_t and undid the formatting change
harshitpant1 Oct 8, 2020
463f831
test for conversion of rgb to cmyk, PR #522.
harshitpant1 Oct 9, 2020
576af18
small formatting changes/fixes
harshitpant1 Oct 10, 2020
7a83e80
Build configuration update for PR #522
harshitpant1 Oct 10, 2020
8b11d70
removed unused header file
harshitpant1 Oct 10, 2020
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39 changes: 21 additions & 18 deletions include/boost/gil/color_convert.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -150,47 +150,50 @@ struct default_color_converter_impl<rgb_t,gray_t> {
/// by Burger, Wilhelm, Burge, Mark J.
/// and it is a gross approximation not precise enough for professional work.
///
/// \todo FIXME: The original implementation did not handle properly signed CMYK pixels as destination
///
template <>
struct default_color_converter_impl<rgb_t, cmyk_t>
{
template <typename SrcPixel, typename DstPixel>
void operator()(SrcPixel const& src, DstPixel& dst) const
{
using src_t = typename channel_type<SrcPixel>::type;
src_t const r = get_color(src, red_t());
src_t const r = get_color(src, red_t());
src_t const g = get_color(src, green_t());
src_t const b = get_color(src, blue_t());

using dst_t = typename channel_type<DstPixel>::type;
dst_t const c = channel_invert(channel_convert<dst_t>(r)); // c = 1 - r
dst_t const m = channel_invert(channel_convert<dst_t>(g)); // m = 1 - g
dst_t const y = channel_invert(channel_convert<dst_t>(b)); // y = 1 - b
dst_t const k = (std::min)(c, (std::min)(m, y)); // k = minimum(c, m, y)
using uint_t = typename channel_type<cmyk8_pixel_t>::type;
uint_t c = channel_invert(channel_convert<uint_t>(r)); // c = 1 - r
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Nitpick: trailing space after r should be removed

uint_t m = channel_invert(channel_convert<uint_t>(g)); // m = 1 - g
uint_t y = channel_invert(channel_convert<uint_t>(b)); // y = 1 - b
uint_t k = (std::min)(c,(std::min)(m,y)); //k = minimum(c, m, y)
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Nitpick: missing space before k in //k


// Apply color correction, strengthening, reducing non-zero components by
// s = 1 / (1 - k) for k < 1, where 1 denotes dst_t max, otherwise s = 1 (literal).
dst_t const dst_max = channel_traits<dst_t>::max_value();
dst_t const s_div = dst_max - k;
uint_t const dst_max = channel_traits<uint_t>::max_value();
uint_t const s_div = dst_max - k;
if (s_div != 0)
{
double const s = dst_max / static_cast<double>(s_div);
get_color(dst, cyan_t()) = static_cast<dst_t>((c - k) * s);
get_color(dst, magenta_t()) = static_cast<dst_t>((m - k) * s);
get_color(dst, yellow_t()) = static_cast<dst_t>((y - k) * s);
double const s = dst_max / static_cast<double>(s_div);
c = (c - k) * s;
m = (m - k) * s;
y = (y - k) * s;
}
else
{
// Black only for k = 1 (max of dst_t)
get_color(dst, cyan_t()) = channel_traits<dst_t>::min_value();
get_color(dst, magenta_t()) = channel_traits<dst_t>::min_value();
get_color(dst, yellow_t()) = channel_traits<dst_t>::min_value();
c = channel_traits<uint_t>::min_value();
m = channel_traits<uint_t>::min_value();
y = channel_traits<uint_t>::min_value();
}
get_color(dst, black_t()) = k;
using dst_t = typename channel_type<DstPixel>::type;
get_color(dst, cyan_t()) = channel_convert<dst_t>(c);
get_color(dst, magenta_t()) = channel_convert<dst_t>(m);
get_color(dst, yellow_t()) = channel_convert<dst_t>(y);
get_color(dst, black_t()) = channel_convert<dst_t>(k);
}
};


/// \ingroup ColorConvert
/// \brief CMYK to RGB (not the fastest code in the world)
///
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325 changes: 325 additions & 0 deletions test/core/color/default_color_converter_rgb_to_cmyk.cpp
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Original file line number Diff line number Diff line change
@@ -0,0 +1,325 @@
#include <boost/gil.hpp>
#include <boost/gil/color_convert.hpp>
#include <boost/gil/rgb.hpp>
#include <boost/gil/cmyk.hpp>
#include <boost/mp11.hpp>
#include <boost/core/lightweight_test.hpp>
#include <type_traits>

#include "test_utility_output_stream.hpp"
#include "test_fixture.hpp"

namespace gil = boost::gil;

void test_unsigned_rgb_to_unsigned_cmyk()
{
// black
{
gil::rgb8_pixel_t src{0, 0, 0};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{0,0,0,255};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// white
{
gil::rgb8_pixel_t src{255, 255, 255};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{0, 0, 0, 0};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// blue
{
gil::rgb8_pixel_t src{0, 0, 255};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{255, 255, 0, 0};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// yellow
{
gil::rgb8_pixel_t src{255, 255, 0};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{0, 0, 255, 0};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 1
{
gil::rgb8_pixel_t src{1, 2, 3};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{170, 85, 0, 252};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 2
{
gil::rgb8_pixel_t src{11, 117, 250};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{243, 135, 0, 5};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 3
{
gil::rgb8_pixel_t src{230, 45, 100};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{0, 205, 144, 25};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 4
{
gil::rgb8_pixel_t src{200, 255, 53};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{55, 0, 202, 0};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
}

void test_signed_rgb_to_unsigned_cmyk()
{
// black
{
gil::rgb8s_pixel_t src{-128, -128, -128};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{0,0,0,255};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// white
{
gil::rgb8s_pixel_t src{127, 127, 127};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{0, 0, 0, 0};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// blue
{
gil::rgb8s_pixel_t src{-128, -128, 127};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{255, 255, 0, 0};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// yellow
{
gil::rgb8s_pixel_t src{127, 127, -128};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{0, 0, 255, 0};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 1
{
gil::rgb8s_pixel_t src{-127, -126, -125};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{170, 85, 0, 252};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 2
{
gil::rgb8s_pixel_t src{-117, -11, 122};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{243, 135, 0, 5};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 3
{
gil::rgb8s_pixel_t src{102, -83, -28};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{0, 205, 144, 25};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 4
{
gil::rgb8s_pixel_t src{72, 127, -75};
gil::cmyk8_pixel_t dst;
gil::cmyk8_pixel_t expected_dst{55, 0, 202, 0};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
}

void test_unsigned_rgb_to_signed_cmyk()
{
// black
{
gil::rgb8_pixel_t src{0, 0, 0};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-128, -128, -128, 127};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// white
{
gil::rgb8_pixel_t src{255, 255, 255};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-128, -128, -128, -128};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// blue
{
gil::rgb8_pixel_t src{0, 0, 255};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{127, 127, -128, -128};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// yellow
{
gil::rgb8_pixel_t src{255, 255, 0};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-128, -128, 127, -128};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 1
{
gil::rgb8_pixel_t src{1, 2, 3};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{42, -43, -128, 124};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 2
{
gil::rgb8_pixel_t src{11, 117, 250};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{115, 7, -128, -123};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 3
{
gil::rgb8_pixel_t src{230, 45, 100};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-128, 77, 16, -103};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 4
{
gil::rgb8_pixel_t src{200, 255, 53};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-73, -128, 74, -128};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
}

void test_signed_rgb_to_signed_cmyk()
{
// black
{
gil::rgb8s_pixel_t src{-128, -128, -128};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-128,-128,-128, 127};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// white
{
gil::rgb8s_pixel_t src{127, 127, 127};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-128, -128, -128, -128};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// blue
{
gil::rgb8s_pixel_t src{-128, -128, 127};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{127, 127, -128, -128};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
// yellow
{
gil::rgb8s_pixel_t src{127, 127, -128};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-128, -128, 127, -128};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 1
{
gil::rgb8s_pixel_t src{-127, -126, -125};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{42, -43, -128, 124};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 2
{
gil::rgb8s_pixel_t src{-117, -11, 122};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{115, 7, -128, -123};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 3
{
gil::rgb8s_pixel_t src{102, -83, -28};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-128, 77, 16, -103};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
//random pixel values 4
{
gil::rgb8s_pixel_t src{72, 127, -75};
gil::cmyk8s_pixel_t dst;
gil::cmyk8s_pixel_t expected_dst{-73, -128, 74, -128};

gil::color_convert(src, dst);
BOOST_TEST_EQ(dst, expected_dst);
}
}

int main()
{
test_unsigned_rgb_to_unsigned_cmyk();
test_signed_rgb_to_unsigned_cmyk();
test_unsigned_rgb_to_signed_cmyk();
test_signed_rgb_to_signed_cmyk();
return ::boost::report_errors();
}