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/*
Copyright 2012 Christian Henning
Use, modification and distribution are subject to 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_HSL_HPP
#define BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_HSL_HPP
////////////////////////////////////////////////////////////////////////////////////////
/// \file hsl.hpp
/// \brief Support for HSL color space
/// \author Christian Henning \n
///
/// \date 2012 \n
///
////////////////////////////////////////////////////////////////////////////////////////
#include <boost/gil/typedefs.hpp>
namespace boost{ namespace gil {
/// \addtogroup ColorNameModel
/// \{
namespace hsl_color_space
{
/// \brief Hue
struct hue_t {};
/// \brief Saturation
struct saturation_t {};
/// \brief Lightness
struct lightness_t {};
}
/// \}
/// \ingroup ColorSpaceModel
typedef mpl::vector3< hsl_color_space::hue_t
, hsl_color_space::saturation_t
, hsl_color_space::lightness_t
> hsl_t;
/// \ingroup LayoutModel
typedef layout<hsl_t> hsl_layout_t;
GIL_DEFINE_ALL_TYPEDEFS(32f, float32_t, hsl)
/// \ingroup ColorConvert
/// \brief RGB to HSL
template <>
struct default_color_converter_impl< rgb_t, hsl_t >
{
template <typename P1, typename P2>
void operator()( const P1& src, P2& dst ) const
{
using namespace hsl_color_space;
// only float32_t for hsl is supported
float32_t temp_red = channel_convert<float32_t>( get_color( src, red_t() ));
float32_t temp_green = channel_convert<float32_t>( get_color( src, green_t() ));
float32_t temp_blue = channel_convert<float32_t>( get_color( src, blue_t() ));
float32_t hue, saturation, lightness;
float32_t min_color = (std::min)( temp_red, (std::min)( temp_green, temp_blue ));
float32_t max_color = (std::max)( temp_red, (std::max)( temp_green, temp_blue ));
if( std::abs( min_color - max_color ) < 0.001 )
{
// rgb color is gray
hue = 0.f;
saturation = 0.f;
// doesn't matter which rgb channel we use.
lightness = temp_red;
}
else
{
float32_t diff = max_color - min_color;
// lightness calculation
lightness = ( min_color + max_color ) / 2.f;
// saturation calculation
if( lightness < 0.5f )
{
saturation = diff
/ ( min_color + max_color );
}
else
{
saturation = ( max_color - min_color )
/ ( 2.f - diff );
}
// hue calculation
if( std::abs( max_color - temp_red ) < 0.0001f )
{
// max_color is red
hue = ( temp_green - temp_blue )
/ diff;
}
else if( std::abs( max_color - temp_green) < 0.0001f )
{
// max_color is green
// 2.0 + (b - r) / (maxColor - minColor);
hue = 2.f
+ ( temp_blue - temp_red )
/ diff;
}
else
{
// max_color is blue
hue = 4.f
+ ( temp_red - temp_blue )
/ diff;
}
hue /= 6.f;
if( hue < 0.f )
{
hue += 1.f;
}
}
get_color( dst,hue_t() ) = hue;
get_color( dst,saturation_t() ) = saturation;
get_color( dst,lightness_t() ) = lightness;
}
};
/// \ingroup ColorConvert
/// \brief HSL to RGB
template <>
struct default_color_converter_impl<hsl_t,rgb_t>
{
template <typename P1, typename P2>
void operator()( const P1& src, P2& dst) const
{
using namespace hsl_color_space;
float32_t red, green, blue;
if( std::abs( get_color( src, saturation_t() )) < 0.0001 )
{
// If saturation is 0, the color is a shade of gray
red = get_color( src, lightness_t() );
green = get_color( src, lightness_t() );
blue = get_color( src, lightness_t() );
}
else
{
float temp1, temp2;
float tempr, tempg, tempb;
//Set the temporary values
if( get_color( src, lightness_t() ) < 0.5 )
{
temp2 = get_color( src, lightness_t() )
* ( 1.f + get_color( src, saturation_t() ) );
}
else
{
temp2 = ( get_color( src, lightness_t() ) + get_color( src, saturation_t() ))
- ( get_color( src, lightness_t() ) * get_color( src, saturation_t() ));
}
temp1 = 2.f
* get_color( src, lightness_t() )
- temp2;
tempr = get_color( src, hue_t() ) + 1.f / 3.f;
if( tempr > 1.f )
{
tempr--;
}
tempg = get_color( src, hue_t() );
tempb = get_color( src, hue_t() ) - 1.f / 3.f;
if( tempb < 0.f )
{
tempb++;
}
//Red
if( tempr < 1.f / 6.f )
{
red = temp1 + ( temp2 - temp1 ) * 6.f * tempr;
}
else if( tempr < 0.5f )
{
red = temp2;
}
else if( tempr < 2.f / 3.f )
{
red = temp1 + (temp2 - temp1)
* (( 2.f / 3.f ) - tempr) * 6.f;
}
else
{
red = temp1;
}
//Green
if( tempg < 1.f / 6.f )
{
green = temp1 + ( temp2 - temp1 ) * 6.f * tempg;
}
else if( tempg < 0.5f )
{
green = temp2;
}
else if( tempg < 2.f / 3.f )
{
green = temp1 + ( temp2 - temp1 )
* (( 2.f / 3.f ) - tempg) * 6.f;
}
else
{
green = temp1;
}
//Blue
if( tempb < 1.f / 6.f )
{
blue = temp1 + (temp2 - temp1) * 6.f * tempb;
}
else if( tempb < 0.5f )
{
blue = temp2;
}
else if( tempb < 2.f / 3.f )
{
blue = temp1 + (temp2 - temp1)
* (( 2.f / 3.f ) - tempb) * 6.f;
}
else
{
blue = temp1;
}
}
get_color(dst,red_t()) =
channel_convert<typename color_element_type< P2, red_t >::type>( red );
get_color(dst,green_t())=
channel_convert<typename color_element_type< P2, green_t >::type>( green );
get_color(dst,blue_t()) =
channel_convert<typename color_element_type< P2, blue_t >::type>( blue );
}
};
} // namespace gil
} // namespace boost
#endif // BOOST_GIL_EXTENSION_TOOLBOX_COLOR_SPACES_HSL_HPP
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