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478 lines
22 KiB
C++
478 lines
22 KiB
C++
/*
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Copyright 2005-2007 Adobe Systems Incorporated
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Use, modification and distribution are subject to the Boost Software License,
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Version 1.0. (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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See http://opensource.adobe.com/gil for most recent version including documentation.
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*/
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/*************************************************************************************************/
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#ifndef GIL_CHANNEL_ALGORITHM_HPP
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#define GIL_CHANNEL_ALGORITHM_HPP
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////////////////////////////////////////////////////////////////////////////////////////
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/// \file
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/// \brief Channel algorithms
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/// \author Lubomir Bourdev and Hailin Jin \n
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/// Adobe Systems Incorporated
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/// \date 2005-2007 \n Last updated on May 6, 2007
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///
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/// Definitions of standard GIL 8-bit, 16-bit, 32-bit channels
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///
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////////////////////////////////////////////////////////////////////////////////////////
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#include "gil_config.hpp"
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#include "channel.hpp"
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#include <boost/mpl/less.hpp>
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#include <boost/mpl/integral_c.hpp>
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#include <boost/mpl/greater.hpp>
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#include <boost/type_traits.hpp>
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namespace boost { namespace gil {
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//#ifdef _MSC_VER
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//#pragma warning(push)
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//#pragma warning(disable: 4309) // disable truncation of constant value warning (using -1 to get the max value of an integral)
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//#endif
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namespace detail {
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// some forward declarations
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template <typename SrcChannelV, typename DstChannelV, bool SrcIsIntegral, bool DstIsIntegral> struct channel_converter_unsigned_impl;
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template <typename SrcChannelV, typename DstChannelV, bool SrcIsGreater> struct channel_converter_unsigned_integral;
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template <typename SrcChannelV, typename DstChannelV, bool SrcLessThanDst, bool SrcDivisible> struct channel_converter_unsigned_integral_impl;
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template <typename SrcChannelV, typename DstChannelV, bool SrcLessThanDst, bool CannotFitInInteger> struct channel_converter_unsigned_integral_nondivisible;
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//////////////////////////////////////
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//// unsigned_integral_max_value - given an unsigned integral channel type, returns its maximum value as an MPL integral constant
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//////////////////////////////////////
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template <typename UnsignedIntegralChannel>
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struct unsigned_integral_max_value : public mpl::integral_c<UnsignedIntegralChannel,-1> {};
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template <>
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struct unsigned_integral_max_value<uint8_t> : public mpl::integral_c<uint32_t,0xFF> {};
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template <>
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struct unsigned_integral_max_value<uint16_t> : public mpl::integral_c<uint32_t,0xFFFF> {};
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template <>
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struct unsigned_integral_max_value<uint32_t> : public mpl::integral_c<uintmax_t,0xFFFFFFFF> {};
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template <int K>
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struct unsigned_integral_max_value<packed_channel_value<K> >
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: public mpl::integral_c<typename packed_channel_value<K>::integer_t, (1<<K)-1> {};
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//////////////////////////////////////
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//// unsigned_integral_num_bits - given an unsigned integral channel type, returns the minimum number of bits needed to represent it
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//////////////////////////////////////
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template <typename UnsignedIntegralChannel>
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struct unsigned_integral_num_bits : public mpl::int_<sizeof(UnsignedIntegralChannel)*8> {};
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template <int K>
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struct unsigned_integral_num_bits<packed_channel_value<K> >
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: public mpl::int_<K> {};
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} // namespace detail
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/**
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\defgroup ChannelConvertAlgorithm channel_convert
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\brief Converting from one channel type to another
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\ingroup ChannelAlgorithm
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Conversion is done as a simple linear mapping of one channel range to the other,
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such that the minimum/maximum value of the source maps to the minimum/maximum value of the destination.
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One implication of this is that the value 0 of signed channels may not be preserved!
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When creating new channel models, it is often a good idea to provide specializations for the channel conversion algorithms, for
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example, for performance optimizations. If the new model is an integral type that can be signed, it is easier to define the conversion
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only for the unsigned type (\p channel_converter_unsigned) and provide specializations of \p detail::channel_convert_to_unsigned
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and \p detail::channel_convert_from_unsigned to convert between the signed and unsigned type.
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Example:
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\code
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// bits32f is a floating point channel with range [0.0f ... 1.0f]
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bits32f src_channel = channel_traits<bits32f>::max_value();
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assert(src_channel == 1);
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// bits8 is 8-bit unsigned integral channel (typedef-ed from unsigned char)
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bits8 dst_channel = channel_convert<bits8>(src_channel);
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assert(dst_channel == 255); // max value goes to max value
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\endcode
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*/
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/**
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\defgroup ChannelConvertUnsignedAlgorithm channel_converter_unsigned
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\ingroup ChannelConvertAlgorithm
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\brief Convert one unsigned/floating point channel to another. Converts both the channel type and range
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@{
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*/
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//////////////////////////////////////
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//// channel_converter_unsigned
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//////////////////////////////////////
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template <typename SrcChannelV, typename DstChannelV> // Model ChannelValueConcept
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struct channel_converter_unsigned
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: public detail::channel_converter_unsigned_impl<SrcChannelV,DstChannelV,is_integral<SrcChannelV>::value,is_integral<DstChannelV>::value> {};
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/// \brief Converting a channel to itself - identity operation
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template <typename T> struct channel_converter_unsigned<T,T> : public detail::identity<T> {};
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namespace detail {
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//////////////////////////////////////
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//// channel_converter_unsigned_impl
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//////////////////////////////////////
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/// \brief This is the default implementation. Performance specializatons are provided
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template <typename SrcChannelV, typename DstChannelV, bool SrcIsIntegral, bool DstIsIntegral>
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struct channel_converter_unsigned_impl : public std::unary_function<DstChannelV,SrcChannelV> {
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DstChannelV operator()(SrcChannelV src) const {
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return DstChannelV(channel_traits<DstChannelV>::min_value() +
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(src - channel_traits<SrcChannelV>::min_value()) / channel_range<SrcChannelV>() * channel_range<DstChannelV>());
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}
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private:
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template <typename C>
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static double channel_range() {
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return double(channel_traits<C>::max_value()) - double(channel_traits<C>::min_value());
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}
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};
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// When both the source and the destination are integral channels, perform a faster conversion
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template <typename SrcChannelV, typename DstChannelV>
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struct channel_converter_unsigned_impl<SrcChannelV,DstChannelV,true,true>
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: public channel_converter_unsigned_integral<SrcChannelV,DstChannelV,
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mpl::less<unsigned_integral_max_value<SrcChannelV>,unsigned_integral_max_value<DstChannelV> >::value > {};
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//////////////////////////////////////
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//// channel_converter_unsigned_integral
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//////////////////////////////////////
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template <typename SrcChannelV, typename DstChannelV>
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struct channel_converter_unsigned_integral<SrcChannelV,DstChannelV,true>
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: public channel_converter_unsigned_integral_impl<SrcChannelV,DstChannelV,true,
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!(unsigned_integral_max_value<DstChannelV>::value % unsigned_integral_max_value<SrcChannelV>::value) > {};
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template <typename SrcChannelV, typename DstChannelV>
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struct channel_converter_unsigned_integral<SrcChannelV,DstChannelV,false>
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: public channel_converter_unsigned_integral_impl<SrcChannelV,DstChannelV,false,
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!(unsigned_integral_max_value<SrcChannelV>::value % unsigned_integral_max_value<DstChannelV>::value) > {};
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//////////////////////////////////////
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//// channel_converter_unsigned_integral_impl
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//////////////////////////////////////
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// Both source and destination are unsigned integral channels,
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// the src max value is less than the dst max value,
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// and the dst max value is divisible by the src max value
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template <typename SrcChannelV, typename DstChannelV>
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struct channel_converter_unsigned_integral_impl<SrcChannelV,DstChannelV,true,true> {
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DstChannelV operator()(SrcChannelV src) const {
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typedef typename unsigned_integral_max_value<DstChannelV>::value_type integer_t;
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static const integer_t mul = unsigned_integral_max_value<DstChannelV>::value / unsigned_integral_max_value<SrcChannelV>::value;
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return DstChannelV(src * mul);
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}
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};
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// Both source and destination are unsigned integral channels,
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// the dst max value is less than (or equal to) the src max value,
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// and the src max value is divisible by the dst max value
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template <typename SrcChannelV, typename DstChannelV>
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struct channel_converter_unsigned_integral_impl<SrcChannelV,DstChannelV,false,true> {
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DstChannelV operator()(SrcChannelV src) const {
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typedef typename unsigned_integral_max_value<SrcChannelV>::value_type integer_t;
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static const integer_t div = unsigned_integral_max_value<SrcChannelV>::value / unsigned_integral_max_value<DstChannelV>::value;
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static const integer_t div2 = div/2;
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return DstChannelV((src + div2) / div);
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}
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};
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// Prevent overflow for the largest integral type
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template <typename DstChannelV>
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struct channel_converter_unsigned_integral_impl<uintmax_t,DstChannelV,false,true> {
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DstChannelV operator()(uintmax_t src) const {
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static const uintmax_t div = unsigned_integral_max_value<bits32>::value / unsigned_integral_max_value<DstChannelV>::value;
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static const uintmax_t div2 = div/2;
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if (src > unsigned_integral_max_value<uintmax_t>::value - div2)
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return unsigned_integral_max_value<DstChannelV>::value;
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return DstChannelV((src + div2) / div);
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}
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};
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// Both source and destination are unsigned integral channels,
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// and the dst max value is not divisible by the src max value
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// See if you can represent the expression (src * dst_max) / src_max in integral form
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template <typename SrcChannelV, typename DstChannelV, bool SrcLessThanDst>
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struct channel_converter_unsigned_integral_impl<SrcChannelV,DstChannelV,SrcLessThanDst,false>
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: public channel_converter_unsigned_integral_nondivisible<SrcChannelV,DstChannelV,SrcLessThanDst,
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mpl::greater<
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mpl::plus<unsigned_integral_num_bits<SrcChannelV>,unsigned_integral_num_bits<DstChannelV> >,
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unsigned_integral_num_bits<uintmax_t>
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>::value> {};
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// Both source and destination are unsigned integral channels,
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// the src max value is less than the dst max value,
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// and the dst max value is not divisible by the src max value
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// The expression (src * dst_max) / src_max fits in an integer
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template <typename SrcChannelV, typename DstChannelV>
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struct channel_converter_unsigned_integral_nondivisible<SrcChannelV,DstChannelV,true,false> {
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DstChannelV operator()(SrcChannelV src) const {
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typedef typename detail::min_fast_uint<unsigned_integral_num_bits<SrcChannelV>::value+unsigned_integral_num_bits<DstChannelV>::value>::type integer_t;
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return DstChannelV(integer_t(src * unsigned_integral_max_value<DstChannelV>::value) / unsigned_integral_max_value<SrcChannelV>::value);
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}
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};
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// Both source and destination are unsigned integral channels,
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// the src max value is less than the dst max value,
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// and the dst max value is not divisible by the src max value
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// The expression (src * dst_max) / src_max cannot fit in an integer (overflows). Use a double
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template <typename SrcChannelV, typename DstChannelV>
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struct channel_converter_unsigned_integral_nondivisible<SrcChannelV,DstChannelV,true,true> {
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DstChannelV operator()(SrcChannelV src) const {
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static const double mul = unsigned_integral_max_value<DstChannelV>::value / double(unsigned_integral_max_value<SrcChannelV>::value);
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return DstChannelV(src * mul);
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}
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};
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// Both source and destination are unsigned integral channels,
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// the dst max value is less than (or equal to) the src max value,
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// and the src max value is not divisible by the dst max value
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template <typename SrcChannelV, typename DstChannelV, bool CannotFit>
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struct channel_converter_unsigned_integral_nondivisible<SrcChannelV,DstChannelV,false,CannotFit> {
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DstChannelV operator()(SrcChannelV src) const {
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typedef typename detail::unsigned_integral_max_value< SrcChannelV >::value_type src_integer_t;
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typedef typename detail::unsigned_integral_max_value< DstChannelV >::value_type dst_integer_t;
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static const double div = unsigned_integral_max_value<SrcChannelV>::value
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/ static_cast< double >( unsigned_integral_max_value<DstChannelV>::value );
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static const src_integer_t div2 = static_cast< src_integer_t >( div / 2.0 );
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return DstChannelV( static_cast< dst_integer_t >(( static_cast< double >( src + div2 ) / div )));
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}
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};
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} // namespace detail
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/////////////////////////////////////////////////////
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/// bits32f conversion
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/////////////////////////////////////////////////////
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template <typename DstChannelV> struct channel_converter_unsigned<bits32f,DstChannelV> : public std::unary_function<bits32f,DstChannelV> {
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DstChannelV operator()(bits32f x) const
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{
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typedef typename detail::unsigned_integral_max_value< DstChannelV >::value_type dst_integer_t;
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return DstChannelV( static_cast< dst_integer_t >(x*channel_traits<DstChannelV>::max_value()+0.5f ));
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}
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};
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template <typename SrcChannelV> struct channel_converter_unsigned<SrcChannelV,bits32f> : public std::unary_function<SrcChannelV,bits32f> {
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bits32f operator()(SrcChannelV x) const { return bits32f(x/float(channel_traits<SrcChannelV>::max_value())); }
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};
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template <> struct channel_converter_unsigned<bits32f,bits32f> : public std::unary_function<bits32f,bits32f> {
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bits32f operator()(bits32f x) const { return x; }
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};
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/// \brief 32 bit <-> float channel conversion
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template <> struct channel_converter_unsigned<bits32,bits32f> : public std::unary_function<bits32,bits32f> {
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bits32f operator()(bits32 x) const {
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// unfortunately without an explicit check it is possible to get a round-off error. We must ensure that max_value of bits32 matches max_value of bits32f
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if (x>=channel_traits<bits32>::max_value()) return channel_traits<bits32f>::max_value();
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return float(x) / float(channel_traits<bits32>::max_value());
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}
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};
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/// \brief 32 bit <-> float channel conversion
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template <> struct channel_converter_unsigned<bits32f,bits32> : public std::unary_function<bits32f,bits32> {
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bits32 operator()(bits32f x) const {
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// unfortunately without an explicit check it is possible to get a round-off error. We must ensure that max_value of bits32 matches max_value of bits32f
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if (x>=channel_traits<bits32f>::max_value()) return channel_traits<bits32>::max_value();
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return bits32(x * channel_traits<bits32>::max_value() + 0.5f);
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}
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};
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/// @}
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namespace detail {
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// Converting from signed to unsigned integral channel.
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// It is both a unary function, and a metafunction (thus requires the 'type' nested typedef, which equals result_type)
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template <typename ChannelValue> // Model ChannelValueConcept
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struct channel_convert_to_unsigned : public detail::identity<ChannelValue> {
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typedef ChannelValue type;
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};
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template <> struct channel_convert_to_unsigned<bits8s> : public std::unary_function<bits8s,bits8> {
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typedef bits8 type;
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type operator()(bits8s val) const { return val+128; }
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};
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template <> struct channel_convert_to_unsigned<bits16s> : public std::unary_function<bits16s,bits16> {
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typedef bits16 type;
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type operator()(bits16s val) const { return val+32768; }
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};
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template <> struct channel_convert_to_unsigned<bits32s> : public std::unary_function<bits32s,bits32> {
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typedef bits32 type;
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type operator()(bits32s x) const { return static_cast<bits32>(x+(1<<31)); }
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};
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// Converting from unsigned to signed integral channel
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// It is both a unary function, and a metafunction (thus requires the 'type' nested typedef, which equals result_type)
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template <typename ChannelValue> // Model ChannelValueConcept
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struct channel_convert_from_unsigned : public detail::identity<ChannelValue> {
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typedef ChannelValue type;
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};
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template <> struct channel_convert_from_unsigned<bits8s> : public std::unary_function<bits8,bits8s> {
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typedef bits8s type;
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type operator()(bits8 val) const { return val-128; }
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};
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template <> struct channel_convert_from_unsigned<bits16s> : public std::unary_function<bits16,bits16s> {
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typedef bits16s type;
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type operator()(bits16 val) const { return val-32768; }
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};
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template <> struct channel_convert_from_unsigned<bits32s> : public std::unary_function<bits32,bits32s> {
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typedef bits32s type;
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type operator()(bits32 x) const { return static_cast<bits32s>(x-(1<<31)); }
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};
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} // namespace detail
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/// \ingroup ChannelConvertAlgorithm
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/// \brief A unary function object converting between channel types
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template <typename SrcChannelV, typename DstChannelV> // Model ChannelValueConcept
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struct channel_converter : public std::unary_function<SrcChannelV,DstChannelV> {
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DstChannelV operator()(const SrcChannelV& src) const {
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typedef detail::channel_convert_to_unsigned<SrcChannelV> to_unsigned;
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typedef detail::channel_convert_from_unsigned<DstChannelV> from_unsigned;
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typedef channel_converter_unsigned<typename to_unsigned::result_type, typename from_unsigned::argument_type> converter_unsigned;
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return from_unsigned()(converter_unsigned()(to_unsigned()(src)));
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}
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};
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/// \ingroup ChannelConvertAlgorithm
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/// \brief Converting from one channel type to another.
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template <typename DstChannel, typename SrcChannel> // Model ChannelConcept (could be channel references)
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inline typename channel_traits<DstChannel>::value_type channel_convert(const SrcChannel& src) {
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return channel_converter<typename channel_traits<SrcChannel>::value_type,
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typename channel_traits<DstChannel>::value_type>()(src);
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}
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/// \ingroup ChannelConvertAlgorithm
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/// \brief Same as channel_converter, except it takes the destination channel by reference, which allows
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/// us to move the templates from the class level to the method level. This is important when invoking it
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/// on heterogeneous pixels.
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struct default_channel_converter {
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template <typename Ch1, typename Ch2>
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void operator()(const Ch1& src, Ch2& dst) const {
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dst=channel_convert<Ch2>(src);
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}
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};
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namespace detail {
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// fast integer division by 255
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inline uint32_t div255(uint32_t in) { uint32_t tmp=in+128; return (tmp + (tmp>>8))>>8; }
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// fast integer divison by 32768
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inline uint32_t div32768(uint32_t in) { return (in+16384)>>15; }
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}
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/**
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\defgroup ChannelMultiplyAlgorithm channel_multiply
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\ingroup ChannelAlgorithm
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\brief Multiplying unsigned channel values of the same type. Performs scaled multiplication result = a * b / max_value
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Example:
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\code
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bits8 x=128;
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bits8 y=128;
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bits8 mul = channel_multiply(x,y);
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assert(mul == 64); // 64 = 128 * 128 / 255
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\endcode
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*/
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/// @{
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/// \brief This is the default implementation. Performance specializatons are provided
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template <typename ChannelValue>
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struct channel_multiplier_unsigned : public std::binary_function<ChannelValue,ChannelValue,ChannelValue> {
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ChannelValue operator()(ChannelValue a, ChannelValue b) const {
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return ChannelValue(a / double(channel_traits<ChannelValue>::max_value()) * b);
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}
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};
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/// \brief Specialization of channel_multiply for 8-bit unsigned channels
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template<> struct channel_multiplier_unsigned<bits8> : public std::binary_function<bits8,bits8,bits8> {
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bits8 operator()(bits8 a, bits8 b) const { return bits8(detail::div255(uint32_t(a) * uint32_t(b))); }
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};
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/// \brief Specialization of channel_multiply for 16-bit unsigned channels
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template<> struct channel_multiplier_unsigned<bits16> : public std::binary_function<bits16,bits16,bits16> {
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bits16 operator()(bits16 a, bits16 b) const { return bits16((uint32_t(a) * uint32_t(b))/65535); }
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};
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/// \brief Specialization of channel_multiply for float 0..1 channels
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template<> struct channel_multiplier_unsigned<bits32f> : public std::binary_function<bits32f,bits32f,bits32f> {
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bits32f operator()(bits32f a, bits32f b) const { return a*b; }
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};
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/// \brief A function object to multiply two channels. result = a * b / max_value
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template <typename ChannelValue>
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struct channel_multiplier : public std::binary_function<ChannelValue, ChannelValue, ChannelValue> {
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ChannelValue operator()(ChannelValue a, ChannelValue b) const {
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typedef detail::channel_convert_to_unsigned<ChannelValue> to_unsigned;
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typedef detail::channel_convert_from_unsigned<ChannelValue> from_unsigned;
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typedef channel_multiplier_unsigned<typename to_unsigned::result_type> multiplier_unsigned;
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return from_unsigned()(multiplier_unsigned()(to_unsigned()(a), to_unsigned()(b)));
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}
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|
};
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|
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/// \brief A function multiplying two channels. result = a * b / max_value
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|
template <typename Channel> // Models ChannelConcept (could be a channel reference)
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inline typename channel_traits<Channel>::value_type channel_multiply(Channel a, Channel b) {
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return channel_multiplier<typename channel_traits<Channel>::value_type>()(a,b);
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}
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/// @}
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|
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/**
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|
\defgroup ChannelInvertAlgorithm channel_invert
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|
\ingroup ChannelAlgorithm
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\brief Returns the inverse of a channel. result = max_value - x + min_value
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|
|
|
Example:
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|
\code
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|
// bits8 == uint8_t == unsigned char
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|
bits8 x=255;
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|
bits8 inv = channel_invert(x);
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|
assert(inv == 0);
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|
\endcode
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|
*/
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|
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/// \brief Default implementation. Provide overloads for performance
|
|
/// \ingroup ChannelInvertAlgorithm channel_invert
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|
template <typename Channel> // Models ChannelConcept (could be a channel reference)
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|
inline typename channel_traits<Channel>::value_type channel_invert(Channel x) {
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|
return channel_traits<Channel>::max_value()-x + channel_traits<Channel>::min_value();
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|
}
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|
|
|
//#ifdef _MSC_VER
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|
//#pragma warning(pop)
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|
//#endif
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|
|
|
} } // namespace boost::gil
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|
|
|
#endif
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