comparison DEPENDENCIES/generic/include/boost/gil/gil_concept.hpp @ 16:2665513ce2d3

Add boost headers

+/*
+    Copyright 2005-2007 Adobe Systems Incorporated
+   
+    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).
+
+    See http://opensource.adobe.com/gil for most recent version including documentation.
+*/
+
+/*************************************************************************************************/
+
+#ifndef GIL_CONCEPT_H
+#define GIL_CONCEPT_H
+
+////////////////////////////////////////////////////////////////////////////////////////
+/// \file               
+/// \brief Concept check classes for GIL concepts
+/// \author Lubomir Bourdev and Hailin Jin \n
+///         Adobe Systems Incorporated
+/// \date   2005-2007 \n Last updated on February 12, 2007
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+#include <functional>
+#include "gil_config.hpp"
+#include <boost/type_traits.hpp>
+#include <boost/utility/enable_if.hpp>
+#include <boost/concept_check.hpp>
+#include <boost/iterator/iterator_concepts.hpp>
+#include <boost/mpl/and.hpp>
+#include <boost/mpl/size.hpp>
+
+namespace boost { namespace gil {
+template <typename T> struct channel_traits;
+template <typename P> struct is_pixel;
+template <typename dstT, typename srcT>
+typename channel_traits<dstT>::value_type channel_convert(const srcT& val);
+template <typename T> class point2;
+template <std::size_t K, typename T> const T& axis_value(const point2<T>& p);
+template <std::size_t K, typename T>       T& axis_value(      point2<T>& p);
+template <typename ColorBase, int K> struct kth_element_type;
+template <typename ColorBase, int K> struct kth_element_reference_type;
+template <typename ColorBase, int K> struct kth_element_const_reference_type;
+template <typename ColorBase, int K> struct kth_semantic_element_reference_type;
+template <typename ColorBase, int K> struct kth_semantic_element_const_reference_type;
+template <typename ColorBase> struct size;
+template <typename ColorBase> struct element_type;
+template <typename T> struct channel_type;
+template <typename T> struct color_space_type;
+template <typename T> struct channel_mapping_type;
+template <typename T> struct is_planar;
+template <typename T> struct num_channels;
+
+template <typename It> struct const_iterator_type;
+template <typename It> struct iterator_is_mutable;
+template <typename It> struct is_iterator_adaptor;
+template <typename It, typename NewBaseIt> struct iterator_adaptor_rebind;
+template <typename It> struct iterator_adaptor_get_base;
+
+
+// forward-declare at_c
+namespace detail { template <typename Element, typename Layout, int K> struct homogeneous_color_base; }
+template <int K, typename E, typename L, int N>
+typename add_reference<E>::type                           at_c(      detail::homogeneous_color_base<E,L,N>& p);
+
+template <int K, typename E, typename L, int N>
+typename add_reference<typename add_const<E>::type>::type at_c(const detail::homogeneous_color_base<E,L,N>& p);
+
+#if !defined(_MSC_VER)  || _MSC_VER > 1310
+template <typename P, typename C, typename L> struct packed_pixel;
+template <int K, typename P, typename C, typename L>
+typename kth_element_reference_type<packed_pixel<P,C,L>, K>::type 
+at_c(packed_pixel<P,C,L>& p);
+
+template <int K, typename P, typename C, typename L>
+typename kth_element_const_reference_type<packed_pixel<P,C,L>,K>::type 
+at_c(const packed_pixel<P,C,L>& p);
+
+template <typename B, typename C, typename L, bool M> struct bit_aligned_pixel_reference;
+
+template <int K, typename B, typename C, typename L, bool M> inline
+typename kth_element_reference_type<bit_aligned_pixel_reference<B,C,L,M>, K>::type
+at_c(const bit_aligned_pixel_reference<B,C,L,M>& p);
+#endif
+
+// Forward-declare semantic_at_c
+template <int K, typename ColorBase>
+typename disable_if<is_const<ColorBase>,typename kth_semantic_element_reference_type<ColorBase,K>::type>::type semantic_at_c(ColorBase& p);
+template <int K, typename ColorBase>
+typename kth_semantic_element_const_reference_type<ColorBase,K>::type semantic_at_c(const ColorBase& p);
+
+template <typename T> struct dynamic_x_step_type;
+template <typename T> struct dynamic_y_step_type;
+template <typename T> struct transposed_type;
+
+namespace detail {
+template <typename T>
+void initialize_it(T& x) {}
+} // namespace detail
+
+template <typename T>
+struct remove_const_and_reference : public remove_const<typename remove_reference<T>::type> {};
+
+#ifdef BOOST_GIL_USE_CONCEPT_CHECK
+    #define GIL_CLASS_REQUIRE(type_var, ns, concept) BOOST_CLASS_REQUIRE(type_var, ns, concept);
+    template <typename C> void gil_function_requires() { function_requires<C>(); }
+#else
+    #define GIL_CLASS_REQUIRE(T,NS,C) 
+    template <typename C> void gil_function_requires() {}
+#endif
+
+/// \ingroup BasicConcepts
+/**
+\code
+auto concept DefaultConstructible<typename T> {
+    T::T();    
+};
+\endcode
+*/
+template <typename T>
+struct DefaultConstructible {
+    void constraints() {
+        function_requires<boost::DefaultConstructibleConcept<T> >();
+    }
+};
+
+/// \ingroup BasicConcepts
+/**
+\codeauto concept CopyConstructible<typename T> {
+    T::T(T);
+    T::~T();
+};
+\endcode
+*/
+template <typename T>
+struct CopyConstructible {
+    void constraints() {
+        function_requires<boost::CopyConstructibleConcept<T> >();
+    }
+};
+
+/// \ingroup BasicConcepts
+/**
+\code
+auto concept Assignable<typename T, typename U = T> {
+    typename result_type;
+    result_type operator=(T&, U);    
+};
+\endcode
+*/
+template <typename T>
+struct Assignable {
+    void constraints() {
+        function_requires<boost::AssignableConcept<T> >();
+    }
+};
+/// \ingroup BasicConcepts
+/**
+\code
+auto concept EqualityComparable<typename T, typename U = T> {
+    bool operator==(T x, T y);    
+    bool operator!=(T x, T y) { return !(x==y); }
+};
+\endcode
+*/
+template <typename T>
+struct EqualityComparable {
+    void constraints() {
+        function_requires<boost::EqualityComparableConcept<T> >();
+    }
+};
+
+/// \ingroup BasicConcepts
+/**
+\code
+concept SameType<typename T, typename U>;// unspecified
+\endcode
+*/
+
+template <typename T, typename U>
+struct SameType {
+    void constraints() {
+        BOOST_STATIC_ASSERT((boost::is_same<T,U>::value_core));
+    }
+};
+
+/// \ingroup BasicConcepts
+/**
+\code
+auto concept Swappable<typename T> {
+    void swap(T&,T&);
+};
+\endcode
+*/
+template <typename T>
+struct Swappable {
+    void constraints() {
+        using std::swap;
+        swap(x,y);
+    }
+    T x,y;
+};
+
+/// \ingroup BasicConcepts
+/**
+\code
+auto concept Regular<typename T> : DefaultConstructible<T>, CopyConstructible<T>, EqualityComparable<T>, 
+                                   Assignable<T>, Swappable<T> {};
+\endcode
+*/
+
+template <typename T>
+struct Regular {
+    void constraints() {
+        gil_function_requires< boost::DefaultConstructibleConcept<T> >();
+        gil_function_requires< boost::CopyConstructibleConcept<T> >();              
+        gil_function_requires< boost::EqualityComparableConcept<T> >(); // ==, !=
+        gil_function_requires< boost::AssignableConcept<T> >();
+        gil_function_requires< Swappable<T> >();
+    }
+};
+
+/// \ingroup BasicConcepts
+/**
+\code
+auto concept Metafunction<typename T> {
+    typename type;
+};
+\endcode
+*/
+template <typename T>
+struct Metafunction {
+    void constraints() {
+        typedef typename T::type type;
+    }
+};
+////////////////////////////////////////////////////////////////////////////////////////
+//
+//          POINT CONCEPTS
+// 
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \brief N-dimensional point concept
+/// \ingroup PointConcept
+/**
+\code
+concept PointNDConcept<typename T> : Regular<T> {    
+    // the type of a coordinate along each axis
+    template <size_t K> struct axis; where Metafunction<axis>;
+            
+    const size_t num_dimensions;
+    
+    // accessor/modifier of the value of each axis.
+    template <size_t K> const typename axis<K>::type& T::axis_value() const;
+    template <size_t K>       typename axis<K>::type& T::axis_value();
+};
+\endcode
+*/
+
+template <typename P>
+struct PointNDConcept {
+    void constraints() {
+        gil_function_requires< Regular<P> >();
+
+        typedef typename P::value_type value_type;
+        static const std::size_t N=P::num_dimensions; ignore_unused_variable_warning(N);
+        typedef typename P::template axis<0>::coord_t FT;
+        typedef typename P::template axis<N-1>::coord_t LT;
+        FT ft=gil::axis_value<0>(point);
+        axis_value<0>(point)=ft;
+        LT lt=axis_value<N-1>(point);
+        axis_value<N-1>(point)=lt;
+    
+        value_type v=point[0];  ignore_unused_variable_warning(v);
+        point[0]=point[0];
+    }
+    P point;
+};
+
+/// \brief 2-dimensional point concept
+/// \ingroup PointConcept
+/**
+\code
+concept Point2DConcept<typename T> : PointNDConcept<T> {    
+    where num_dimensions == 2;
+    where SameType<axis<0>::type, axis<1>::type>;
+
+    typename value_type = axis<0>::type;
+
+    const value_type& operator[](const T&, size_t i);
+          value_type& operator[](      T&, size_t i);
+
+    value_type x,y;
+};
+\endcode
+*/
+
+template <typename P>
+struct Point2DConcept {
+    void constraints() {
+        gil_function_requires< PointNDConcept<P> >();
+        BOOST_STATIC_ASSERT(P::num_dimensions == 2);
+        point.x=point.y;
+        point[0]=point[1];
+    }
+    P point;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////
+//
+//          ITERATOR MUTABILITY CONCEPTS
+//
+// Taken from boost's concept_check.hpp. Isolating mutability to result in faster compile time 
+//
+////////////////////////////////////////////////////////////////////////////////////////
+
+namespace detail {
+    template <class TT> // Preconditions: TT Models boost_concepts::ForwardTraversalConcept
+    struct ForwardIteratorIsMutableConcept {
+        void constraints() {
+            *i++ = *i;         // require postincrement and assignment
+        }
+        TT i;
+    };
+
+    template <class TT> // Preconditions: TT Models boost::BidirectionalIteratorConcept
+    struct BidirectionalIteratorIsMutableConcept {
+        void constraints() {
+            gil_function_requires< ForwardIteratorIsMutableConcept<TT> >();
+            *i-- = *i;                  // require postdecrement and assignment
+        }
+        TT i;
+    };
+
+    template <class TT> // Preconditions: TT Models boost_concepts::RandomAccessTraversalConcept
+    struct RandomAccessIteratorIsMutableConcept {
+        void constraints() {
+            gil_function_requires< BidirectionalIteratorIsMutableConcept<TT> >();
+            typename std::iterator_traits<TT>::difference_type n=0; ignore_unused_variable_warning(n);
+            i[n] = *i;                  // require element access and assignment
+        }
+        TT i;
+    };
+}   // namespace detail
+
+////////////////////////////////////////////////////////////////////////////////////////
+//
+//         COLOR SPACE CONCEPTS
+//
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \brief Color space type concept
+/// \ingroup ColorSpaceAndLayoutConcept
+/**
+\code
+concept ColorSpaceConcept<MPLRandomAccessSequence Cs> {
+   // An MPL Random Access Sequence, whose elements are color tags
+};
+\endcode
+*/
+template <typename Cs>
+struct ColorSpaceConcept {
+    void constraints() {
+        // An MPL Random Access Sequence, whose elements are color tags
+    }
+};
+
+template <typename ColorSpace1, typename ColorSpace2>  // Models ColorSpaceConcept
+struct color_spaces_are_compatible : public is_same<ColorSpace1,ColorSpace2> {};
+
+/// \brief Two color spaces are compatible if they are the same
+/// \ingroup ColorSpaceAndLayoutConcept
+/**
+\code
+concept ColorSpacesCompatibleConcept<ColorSpaceConcept Cs1, ColorSpaceConcept Cs2> {
+    where SameType<Cs1,Cs2>;
+};
+\endcode
+*/
+template <typename Cs1, typename Cs2>
+struct ColorSpacesCompatibleConcept {
+    void constraints() {
+        BOOST_STATIC_ASSERT((color_spaces_are_compatible<Cs1,Cs2>::value));
+    }
+};
+
+/// \brief Channel mapping concept
+/// \ingroup ColorSpaceAndLayoutConcept
+/**
+\code
+concept ChannelMappingConcept<MPLRandomAccessSequence CM> {
+   // An MPL Random Access Sequence, whose elements model MPLIntegralConstant representing a permutation
+};
+\endcode
+*/
+template <typename CM>
+struct ChannelMappingConcept {
+    void constraints() {
+        // An MPL Random Access Sequence, whose elements model MPLIntegralConstant representing a permutation
+    }
+};
+
+
+
+////////////////////////////////////////////////////////////////////////////////////////
+///
+///         Channel CONCEPTS
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \ingroup ChannelConcept
+/// \brief A channel is the building block of a color. Color is defined as a mixture of primary colors and a channel defines the degree to which each primary color is used in the mixture.
+/**         
+For example, in the RGB color space, using 8-bit unsigned channels, the color red is defined as [255 0 0], which means maximum of Red, and no Green and Blue.
+    
+Built-in scalar types, such as \p int and \p float, are valid GIL channels. In more complex scenarios, channels may be represented as bit ranges or even individual bits.
+In such cases special classes are needed to represent the value and reference to a channel.
+    
+Channels have a traits class, \p channel_traits, which defines their associated types as well as their operating ranges.
+
+\code
+concept ChannelConcept<typename T> : EqualityComparable<T> {
+    typename value_type      = T;        // use channel_traits<T>::value_type to access it
+    typename reference       = T&;       // use channel_traits<T>::reference to access it
+    typename pointer         = T*;       // use channel_traits<T>::pointer to access it
+    typename const_reference = const T&; // use channel_traits<T>::const_reference to access it
+    typename const_pointer   = const T*; // use channel_traits<T>::const_pointer to access it
+    static const bool is_mutable;        // use channel_traits<T>::is_mutable to access it
+
+    static T min_value();                // use channel_traits<T>::min_value to access it
+    static T max_value();                // use channel_traits<T>::min_value to access it
+};
+\endcode
+*/
+template <typename T>
+struct ChannelConcept {
+    void constraints() {
+        gil_function_requires< boost::EqualityComparableConcept<T> >(); 
+        
+        typedef typename channel_traits<T>::value_type v;
+        typedef typename channel_traits<T>::reference r;
+        typedef typename channel_traits<T>::pointer p;
+        typedef typename channel_traits<T>::const_reference cr;
+        typedef typename channel_traits<T>::const_pointer cp;
+
+        channel_traits<T>::min_value();
+        channel_traits<T>::max_value();
+    }
+
+     T c;
+};
+
+namespace detail {
+    // Preconditions: T models ChannelConcept
+    template <typename T>
+    struct ChannelIsMutableConcept {
+        void constraints() {
+            c=c;
+            using std::swap;
+            swap(c,c);
+        }
+        T c;
+    };
+}
+
+/// \brief A channel that allows for modifying its value
+/// \ingroup ChannelConcept
+/**
+\code
+concept MutableChannelConcept<ChannelConcept T> : Assignable<T>, Swappable<T> {};
+\endcode
+*/
+template <typename T>
+struct MutableChannelConcept {
+    void constraints() {
+        gil_function_requires<ChannelConcept<T> >();
+        gil_function_requires<detail::ChannelIsMutableConcept<T> >();
+    }
+};
+
+/// \brief A channel that supports default construction. 
+/// \ingroup ChannelConcept
+/**
+\code
+concept ChannelValueConcept<ChannelConcept T> : Regular<T> {}; 
+\endcode
+*/
+template <typename T>
+struct ChannelValueConcept {
+    void constraints() {
+        gil_function_requires<ChannelConcept<T> >();
+        gil_function_requires<Regular<T> >();
+    }
+};
+
+
+/// \brief Predicate metafunction returning whether two channels are compatible
+/// \ingroup ChannelAlgorithm
+///
+/// Channels are considered compatible if their value types (ignoring constness and references) are the same.
+/**
+Example:
+
+\code
+BOOST_STATIC_ASSERT((channels_are_compatible<bits8, const bits8&>::value));
+\endcode
+*/
+template <typename T1, typename T2>  // Models GIL Pixel
+struct channels_are_compatible 
+    : public is_same<typename channel_traits<T1>::value_type, typename channel_traits<T2>::value_type> {};
+
+/// \brief Channels are compatible if their associated value types (ignoring constness and references) are the same
+/// \ingroup ChannelConcept
+/**
+\code
+concept ChannelsCompatibleConcept<ChannelConcept T1, ChannelConcept T2> {
+    where SameType<T1::value_type, T2::value_type>;
+};
+\endcode
+*/
+template <typename T1, typename T2>
+struct ChannelsCompatibleConcept {
+    void constraints() {
+        BOOST_STATIC_ASSERT((channels_are_compatible<T1,T2>::value));
+    }
+};
+
+/// \brief A channel is convertible to another one if the \p channel_convert algorithm is defined for the two channels
+///
+/// Convertibility is non-symmetric and implies that one channel can be converted to another. Conversion is explicit and often lossy operation.
+/// \ingroup ChannelConcept
+/**
+\code
+concept ChannelConvertibleConcept<ChannelConcept SrcChannel, ChannelValueConcept DstChannel> {
+    DstChannel channel_convert(const SrcChannel&);
+};
+\endcode
+*/
+template <typename SrcChannel, typename DstChannel>
+struct ChannelConvertibleConcept {
+    void constraints() {
+        gil_function_requires<ChannelConcept<SrcChannel> >();
+        gil_function_requires<MutableChannelConcept<DstChannel> >();
+        dst=channel_convert<DstChannel,SrcChannel>(src); ignore_unused_variable_warning(dst);
+    }
+    SrcChannel src;
+    DstChannel dst;
+};
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////////////
+///
+///         COLOR BASE CONCEPTS
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \ingroup ColorBaseConcept
+/// \brief A color base is a container of color elements (such as channels, channel references or channel pointers)
+/** 
+The most common use of color base is in the implementation of a pixel, in which case the color
+elements are channel values. The color base concept, however, can be used in other scenarios. For example, a planar pixel has channels that are not
+contiguous in memory. Its reference is a proxy class that uses a color base whose elements are channel references. Its iterator uses a color base
+whose elements are channel iterators.
+
+A color base must have an associated layout (which consists of a color space, as well as an ordering of the channels).
+There are two ways to index the elements of a color base: A physical index corresponds to the way they are ordered in memory, and
+a semantic index corresponds to the way the elements are ordered in their color space.
+For example, in the RGB color space the elements are ordered as {red_t, green_t, blue_t}. For a color base with a BGR layout, the first element
+in physical ordering is the blue element, whereas the first semantic element is the red one.
+Models of \p ColorBaseConcept are required to provide the \p at_c<K>(ColorBase) function, which allows for accessing the elements based on their
+physical order. GIL provides a \p semantic_at_c<K>(ColorBase) function (described later) which can operate on any model of ColorBaseConcept and returns
+the corresponding semantic element.
+
+\code
+concept ColorBaseConcept<typename T> : CopyConstructible<T>, EqualityComparable<T> {
+    // a GIL layout (the color space and element permutation)
+    typename layout_t;     
+        
+    // The type of K-th element
+    template <int K> struct kth_element_type;                 where Metafunction<kth_element_type>;
+    
+    // The result of at_c
+    template <int K> struct kth_element_const_reference_type; where Metafunction<kth_element_const_reference_type>;        
+    
+    template <int K> kth_element_const_reference_type<T,K>::type at_c(T);
+
+    // Copy-constructible and equality comparable with other compatible color bases
+    template <ColorBaseConcept T2> where { ColorBasesCompatibleConcept<T,T2> } 
+        T::T(T2);
+    template <ColorBaseConcept T2> where { ColorBasesCompatibleConcept<T,T2> } 
+        bool operator==(const T&, const T2&);
+    template <ColorBaseConcept T2> where { ColorBasesCompatibleConcept<T,T2> } 
+        bool operator!=(const T&, const T2&);
+
+};
+\endcode
+*/
+
+template <typename ColorBase>
+struct ColorBaseConcept {
+    void constraints() {
+        gil_function_requires< CopyConstructible<ColorBase> >();
+        gil_function_requires< EqualityComparable<ColorBase> >();
+
+        typedef typename ColorBase::layout_t::color_space_t color_space_t;
+        gil_function_requires<ColorSpaceConcept<color_space_t> >();
+
+        typedef typename ColorBase::layout_t::channel_mapping_t channel_mapping_t;
+        // TODO: channel_mapping_t must be an MPL RandomAccessSequence
+
+        static const std::size_t num_elements = size<ColorBase>::value;
+
+        typedef typename kth_element_type<ColorBase,num_elements-1>::type TN; 
+        typedef typename kth_element_const_reference_type<ColorBase,num_elements-1>::type CR; 
+
+#if !defined(_MSC_VER) || _MSC_VER > 1310
+        CR cr=at_c<num_elements-1>(cb);  ignore_unused_variable_warning(cr);
+#endif
+
+        // functions that work for every pixel (no need to require them)
+        semantic_at_c<0>(cb);
+        semantic_at_c<num_elements-1>(cb);
+        // also static_max(cb), static_min(cb), static_fill(cb,value), and all variations of static_for_each(), static_generate(), static_transform()
+    }
+
+    ColorBase cb;
+};
+
+/// \ingroup ColorBaseConcept
+/// \brief Color base which allows for modifying its elements
+/** 
+
+\code
+concept MutableColorBaseConcept<ColorBaseConcept T> : Assignable<T>, Swappable<T> {
+    template <int K> struct kth_element_reference_type;       where Metafunction<kth_element_reference_type>;
+
+    template <int K> kth_element_reference_type<kth_element_type<T,K>::type>::type at_c(T);
+    
+    template <ColorBaseConcept T2> where { ColorBasesCompatibleConcept<T,T2> } 
+        T& operator=(T&, const T2&);
+};
+\endcode
+*/
+template <typename ColorBase>
+struct MutableColorBaseConcept {
+    void constraints() {
+        gil_function_requires< ColorBaseConcept<ColorBase> >();
+        gil_function_requires< Assignable<ColorBase> >();
+        gil_function_requires< Swappable<ColorBase> >();
+
+        typedef typename kth_element_reference_type<ColorBase, 0>::type CR; 
+
+#if !defined(_MSC_VER) || _MSC_VER > 1310
+        CR r=at_c<0>(cb);
+        at_c<0>(cb)=r;
+#endif
+    }
+
+    ColorBase cb;
+};
+
+/// \ingroup ColorBaseConcept
+/// \brief Color base that also has a default-constructor. Refines Regular
+/** 
+\code
+concept ColorBaseValueConcept<typename T> : MutableColorBaseConcept<T>, Regular<T> {
+};
+\endcode
+*/
+template <typename ColorBase>
+struct ColorBaseValueConcept {
+    void constraints() {
+        gil_function_requires< MutableColorBaseConcept<ColorBase> >();
+        gil_function_requires< Regular<ColorBase> >();
+    }
+};
+
+/// \ingroup ColorBaseConcept
+/// \brief Color base whose elements all have the same type
+/** 
+\code
+concept HomogeneousColorBaseConcept<ColorBaseConcept CB> {
+    // For all K in [0 ... size<C1>::value-1):
+    //     where SameType<kth_element_type<CB,K>::type, kth_element_type<CB,K+1>::type>;    
+    kth_element_const_reference_type<CB,0>::type dynamic_at_c(const CB&, std::size_t n) const;
+};
+\endcode
+*/
+
+template <typename ColorBase>
+struct HomogeneousColorBaseConcept {
+    void constraints() {
+        gil_function_requires< ColorBaseConcept<ColorBase> >();
+
+        static const std::size_t num_elements = size<ColorBase>::value;
+
+        typedef typename kth_element_type<ColorBase,0>::type T0; 
+        typedef typename kth_element_type<ColorBase,num_elements-1>::type TN; 
+
+        BOOST_STATIC_ASSERT((is_same<T0,TN>::value));   // better than nothing
+        typedef typename kth_element_const_reference_type<ColorBase,0>::type CRef0; 
+        CRef0 e0=dynamic_at_c(cb,0);
+    }
+    ColorBase cb;
+};
+
+/// \ingroup ColorBaseConcept
+/// \brief Homogeneous color base that allows for modifying its elements
+/** 
+
+\code
+concept MutableHomogeneousColorBaseConcept<ColorBaseConcept CB> : HomogeneousColorBaseConcept<CB> {
+    kth_element_reference_type<CB,0>::type dynamic_at_c(CB&, std::size_t n);
+};
+\endcode
+*/
+
+template <typename ColorBase>
+struct MutableHomogeneousColorBaseConcept {
+    void constraints() {
+        gil_function_requires< ColorBaseConcept<ColorBase> >();
+        gil_function_requires< HomogeneousColorBaseConcept<ColorBase> >();
+        typedef typename kth_element_reference_type<ColorBase, 0>::type R0;
+        R0 x=dynamic_at_c(cb,0);
+        dynamic_at_c(cb,0) = dynamic_at_c(cb,0);
+    }
+    ColorBase cb;
+};
+
+/// \ingroup ColorBaseConcept
+/// \brief Homogeneous color base that also has a default constructor. Refines Regular.
+/** 
+
+\code
+concept HomogeneousColorBaseValueConcept<typename T> : MutableHomogeneousColorBaseConcept<T>, Regular<T> {
+};
+\endcode
+*/
+
+template <typename ColorBase>
+struct HomogeneousColorBaseValueConcept {
+    void constraints() {
+        gil_function_requires< MutableHomogeneousColorBaseConcept<ColorBase> >();
+        gil_function_requires< Regular<ColorBase> >();
+    }
+};
+
+
+/// \ingroup ColorBaseConcept
+/// \brief Two color bases are compatible if they have the same color space and their elements are compatible, semantic-pairwise.
+/** 
+
+\code
+concept ColorBasesCompatibleConcept<ColorBaseConcept C1, ColorBaseConcept C2> {
+    where SameType<C1::layout_t::color_space_t, C2::layout_t::color_space_t>;
+    // also, for all K in [0 ... size<C1>::value):
+    //     where Convertible<kth_semantic_element_type<C1,K>::type, kth_semantic_element_type<C2,K>::type>;
+    //     where Convertible<kth_semantic_element_type<C2,K>::type, kth_semantic_element_type<C1,K>::type>;
+};
+\endcode
+*/
+template <typename ColorBase1, typename ColorBase2>
+struct ColorBasesCompatibleConcept {
+    void constraints() {
+        BOOST_STATIC_ASSERT((is_same<typename ColorBase1::layout_t::color_space_t, 
+                                     typename ColorBase2::layout_t::color_space_t>::value));
+//        typedef typename kth_semantic_element_type<ColorBase1,0>::type e1;
+//        typedef typename kth_semantic_element_type<ColorBase2,0>::type e2;
+//        "e1 is convertible to e2"
+    }
+};
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////////////
+///
+///         PIXEL CONCEPTS
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \brief Concept for all pixel-based GIL constructs, such as pixels, iterators, locators, views and images whose value type is a pixel
+/// \ingroup PixelBasedConcept
+/**
+\code
+concept PixelBasedConcept<typename T> {
+    typename color_space_type<T>;     
+        where Metafunction<color_space_type<T> >;
+        where ColorSpaceConcept<color_space_type<T>::type>;
+    typename channel_mapping_type<T>; 
+        where Metafunction<channel_mapping_type<T> >;  
+        where ChannelMappingConcept<channel_mapping_type<T>::type>;
+    typename is_planar<T>;
+        where Metafunction<is_planar<T> >;
+        where SameType<is_planar<T>::type, bool>;
+};
+\endcode
+*/
+template <typename P>
+struct PixelBasedConcept {
+    void constraints() {
+        typedef typename color_space_type<P>::type color_space_t;
+        gil_function_requires<ColorSpaceConcept<color_space_t> >();
+        typedef typename channel_mapping_type<P>::type channel_mapping_t;
+        gil_function_requires<ChannelMappingConcept<channel_mapping_t> >();
+
+        static const bool planar = is_planar<P>::type::value;   ignore_unused_variable_warning(planar);
+
+
+        // This is not part of the concept, but should still work
+        static const std::size_t nc = num_channels<P>::value;
+        ignore_unused_variable_warning(nc);
+    }
+};
+
+/// \brief Concept for homogeneous pixel-based GIL constructs
+/// \ingroup PixelBasedConcept
+/**
+\code
+concept HomogeneousPixelBasedConcept<PixelBasedConcept T> {
+    typename channel_type<T>;         
+        where Metafunction<channel_type<T> >;
+        where ChannelConcept<channel_type<T>::type>;
+};
+\endcode
+*/
+template <typename P>
+struct HomogeneousPixelBasedConcept {
+    void constraints() {
+        gil_function_requires<PixelBasedConcept<P> >();
+        typedef typename channel_type<P>::type channel_t;
+        gil_function_requires<ChannelConcept<channel_t> >();        
+    }
+};
+
+
+/// \brief Pixel concept - A color base whose elements are channels
+/// \ingroup PixelConcept
+/**
+\code
+concept PixelConcept<typename P> : ColorBaseConcept<P>, PixelBasedConcept<P> {    
+    where is_pixel<P>::type::value==true;
+    // where for each K [0..size<P>::value-1]:
+    //      ChannelConcept<kth_element_type<P,K> >;
+        
+    typename P::value_type;       where PixelValueConcept<value_type>;
+    typename P::reference;        where PixelConcept<reference>;
+    typename P::const_reference;  where PixelConcept<const_reference>;
+    static const bool P::is_mutable;
+
+    template <PixelConcept P2> where { PixelConcept<P,P2> } 
+        P::P(P2);
+    template <PixelConcept P2> where { PixelConcept<P,P2> } 
+        bool operator==(const P&, const P2&);
+    template <PixelConcept P2> where { PixelConcept<P,P2> } 
+        bool operator!=(const P&, const P2&);
+}; 
+\endcode
+*/
+
+template <typename P>
+struct PixelConcept {
+    void constraints() {
+        gil_function_requires<ColorBaseConcept<P> >();
+        gil_function_requires<PixelBasedConcept<P> >();
+
+        BOOST_STATIC_ASSERT((is_pixel<P>::value));
+        static const bool is_mutable = P::is_mutable; ignore_unused_variable_warning(is_mutable);
+
+        typedef typename P::value_type      value_type;
+//      gil_function_requires<PixelValueConcept<value_type> >();
+
+        typedef typename P::reference       reference;
+        gil_function_requires<PixelConcept<typename remove_const_and_reference<reference>::type> >();
+
+        typedef typename P::const_reference const_reference;
+        gil_function_requires<PixelConcept<typename remove_const_and_reference<const_reference>::type> >();
+    }
+};
+
+
+/// \brief Pixel concept that allows for changing its channels
+/// \ingroup PixelConcept
+/**
+\code
+concept MutablePixelConcept<PixelConcept P> : MutableColorBaseConcept<P> {
+    where is_mutable==true;
+};
+\endcode
+*/
+template <typename P>
+struct MutablePixelConcept {
+    void constraints() {
+        gil_function_requires<PixelConcept<P> >();
+        BOOST_STATIC_ASSERT(P::is_mutable);
+    }
+};
+/// \brief Homogeneous pixel concept
+/// \ingroup PixelConcept
+/**
+\code
+concept HomogeneousPixelConcept<PixelConcept P> : HomogeneousColorBaseConcept<P>, HomogeneousPixelBasedConcept<P> { 
+    P::template element_const_reference_type<P>::type operator[](P p, std::size_t i) const { return dynamic_at_c(p,i); }
+};
+\endcode
+*/
+template <typename P>
+struct HomogeneousPixelConcept {
+    void constraints() {
+        gil_function_requires<PixelConcept<P> >();
+        gil_function_requires<HomogeneousColorBaseConcept<P> >();
+        gil_function_requires<HomogeneousPixelBasedConcept<P> >();
+        p[0];
+    }
+    P p;
+};
+
+/// \brief Homogeneous pixel concept that allows for changing its channels
+/// \ingroup PixelConcept
+/**
+\code
+concept MutableHomogeneousPixelConcept<HomogeneousPixelConcept P> : MutableHomogeneousColorBaseConcept<P> { 
+    P::template element_reference_type<P>::type operator[](P p, std::size_t i) { return dynamic_at_c(p,i); }
+};
+\endcode
+*/
+template <typename P>
+struct MutableHomogeneousPixelConcept {
+    void constraints() {
+        gil_function_requires<HomogeneousPixelConcept<P> >();
+        gil_function_requires<MutableHomogeneousColorBaseConcept<P> >();
+        p[0]=p[0];
+    }
+    P p;
+};
+
+/// \brief Pixel concept that is a Regular type
+/// \ingroup PixelConcept
+/**
+\code
+concept PixelValueConcept<PixelConcept P> : Regular<P> {
+    where SameType<value_type,P>;
+};    
+\endcode
+*/
+template <typename P>
+struct PixelValueConcept {
+    void constraints() {
+        gil_function_requires<PixelConcept<P> >();
+        gil_function_requires<Regular<P> >();
+    }
+};
+
+/// \brief Homogeneous pixel concept that is a Regular type
+/// \ingroup PixelConcept
+/**
+\code
+concept HomogeneousPixelValueConcept<HomogeneousPixelConcept P> : Regular<P> {
+    where SameType<value_type,P>;
+}; 
+\endcode
+*/
+template <typename P>
+struct HomogeneousPixelValueConcept {
+    void constraints() {
+        gil_function_requires<HomogeneousPixelConcept<P> >();
+        gil_function_requires<Regular<P> >();
+        BOOST_STATIC_ASSERT((is_same<P, typename P::value_type>::value));
+    }
+};
+
+namespace detail {
+    template <typename P1, typename P2, int K>
+    struct channels_are_pairwise_compatible : public 
+        mpl::and_<channels_are_pairwise_compatible<P1,P2,K-1>,
+                         channels_are_compatible<typename kth_semantic_element_reference_type<P1,K>::type,
+                                                 typename kth_semantic_element_reference_type<P2,K>::type> > {};
+                                                 
+    template <typename P1, typename P2>
+    struct channels_are_pairwise_compatible<P1,P2,-1> : public mpl::true_ {};
+}
+
+/// \brief Returns whether two pixels are compatible
+///
+/// Pixels are compatible if their channels and color space types are compatible. Compatible pixels can be assigned and copy constructed from one another.
+/// \ingroup PixelAlgorithm
+template <typename P1, typename P2>  // Models GIL Pixel
+struct pixels_are_compatible 
+    : public mpl::and_<typename color_spaces_are_compatible<typename color_space_type<P1>::type, 
+                                                            typename color_space_type<P2>::type>::type, 
+                       detail::channels_are_pairwise_compatible<P1,P2,num_channels<P1>::value-1> > {};
+
+/// \brief  Concept for pixel compatibility
+///    Pixels are compatible if their channels and color space types are compatible. Compatible pixels can be assigned and copy constructed from one another.
+/// \ingroup PixelConcept
+/**
+\code
+concept PixelsCompatibleConcept<PixelConcept P1, PixelConcept P2> : ColorBasesCompatibleConcept<P1,P2> {
+    // where for each K [0..size<P1>::value):
+    //    ChannelsCompatibleConcept<kth_semantic_element_type<P1,K>::type, kth_semantic_element_type<P2,K>::type>;
+};
+\endcode
+*/
+template <typename P1, typename P2> // precondition: P1 and P2 model PixelConcept
+struct PixelsCompatibleConcept {
+    void constraints() {
+        BOOST_STATIC_ASSERT((pixels_are_compatible<P1,P2>::value));
+    }
+};
+
+/// \brief Pixel convertible concept
+///
+/// Convertibility is non-symmetric and implies that one pixel can be converted to another, approximating the color. Conversion is explicit and sometimes lossy.
+/// \ingroup PixelConcept
+/**
+\code
+template <PixelConcept SrcPixel, MutablePixelConcept DstPixel>
+concept PixelConvertibleConcept {
+    void color_convert(const SrcPixel&, DstPixel&);
+};
+\endcode
+*/
+template <typename SrcP, typename DstP>
+struct PixelConvertibleConcept {
+    void constraints() {
+        gil_function_requires<PixelConcept<SrcP> >();
+        gil_function_requires<MutablePixelConcept<DstP> >();
+        color_convert(src,dst);
+    }
+    SrcP src;
+    DstP dst;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////
+///
+///         DEREFERENCE ADAPTOR CONCEPTS
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \ingroup PixelDereferenceAdaptorConcept
+
+/// \brief Represents a unary function object that can be invoked upon dereferencing a pixel iterator.
+///
+/// This can perform an arbitrary computation, such as color conversion or table lookup
+/**
+\code
+concept PixelDereferenceAdaptorConcept<boost::UnaryFunctionConcept D>
+  : DefaultConstructibleConcept<D>, CopyConstructibleConcept<D>, AssignableConcept<D>  {
+    typename const_t;         where PixelDereferenceAdaptorConcept<const_t>;
+    typename value_type;      where PixelValueConcept<value_type>;
+    typename reference;         // may be mutable
+    typename const_reference;   // must not be mutable
+    static const bool D::is_mutable;
+
+    where Convertible<value_type,result_type>;
+};
+\endcode
+*/
+
+template <typename D>
+struct PixelDereferenceAdaptorConcept {
+    void constraints() {
+        gil_function_requires< boost::UnaryFunctionConcept<D, 
+            typename remove_const_and_reference<typename D::result_type>::type, 
+            typename D::argument_type> >();
+        gil_function_requires< boost::DefaultConstructibleConcept<D> >();
+        gil_function_requires< boost::CopyConstructibleConcept<D> >();              
+        gil_function_requires< boost::AssignableConcept<D> >();
+
+        gil_function_requires<PixelConcept<typename remove_const_and_reference<typename D::result_type>::type> >();
+
+        typedef typename D::const_t const_t;
+        gil_function_requires<PixelDereferenceAdaptorConcept<const_t> >();
+        typedef typename D::value_type value_type;
+        gil_function_requires<PixelValueConcept<value_type> >();
+        typedef typename D::reference reference;                // == PixelConcept (if you remove const and reference)
+        typedef typename D::const_reference const_reference;    // == PixelConcept (if you remove const and reference)
+
+        const bool is_mutable=D::is_mutable; ignore_unused_variable_warning(is_mutable);
+    }
+    D d;
+};
+
+template <typename P>
+struct PixelDereferenceAdaptorArchetype : public std::unary_function<P, P> {
+    typedef PixelDereferenceAdaptorArchetype const_t;
+    typedef typename remove_reference<P>::type value_type;
+    typedef typename add_reference<P>::type reference;
+    typedef reference const_reference;
+    static const bool is_mutable=false;
+    P operator()(P x) const { throw; }
+};
+
+////////////////////////////////////////////////////////////////////////////////////////
+///
+///         Pixel ITERATOR CONCEPTS
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \brief Concept for iterators, locators and views that can define a type just like the given iterator/locator/view, except it supports runtime specified step along the X navigation
+/// \ingroup PixelIteratorConcept
+/**
+\code
+concept HasDynamicXStepTypeConcept<typename T> {
+    typename dynamic_x_step_type<T>;
+        where Metafunction<dynamic_x_step_type<T> >;
+};
+\endcode
+*/
+template <typename T>
+struct HasDynamicXStepTypeConcept {   
+    void constraints() {
+        typedef typename dynamic_x_step_type<T>::type type;
+    }
+};
+
+/// \brief Concept for locators and views that can define a type just like the given locator or view, except it supports runtime specified step along the Y navigation
+/// \ingroup PixelLocatorConcept
+/**
+\code
+concept HasDynamicYStepTypeConcept<typename T> {
+    typename dynamic_y_step_type<T>;
+        where Metafunction<dynamic_y_step_type<T> >;
+};
+\endcode
+*/
+template <typename T>
+struct HasDynamicYStepTypeConcept {   
+    void constraints() {
+        typedef typename dynamic_y_step_type<T>::type type;
+    }
+};
+
+
+/// \brief Concept for locators and views that can define a type just like the given locator or view, except X and Y is swapped
+/// \ingroup PixelLocatorConcept
+/**
+\code
+concept HasTransposedTypeConcept<typename T> {
+    typename transposed_type<T>;
+        where Metafunction<transposed_type<T> >;
+};
+\endcode
+*/
+template <typename T>
+struct HasTransposedTypeConcept {   
+    void constraints() {
+        typedef typename transposed_type<T>::type type;
+    }
+};
+
+/// \defgroup PixelIteratorConceptPixelIterator PixelIteratorConcept
+/// \ingroup PixelIteratorConcept
+/// \brief STL iterator over pixels
+
+/// \ingroup PixelIteratorConceptPixelIterator
+/// \brief An STL random access traversal iterator over a model of PixelConcept.
+/**
+GIL's iterators must also provide the following metafunctions:
+ - \p const_iterator_type<Iterator>:   Returns a read-only equivalent of \p Iterator
+ - \p iterator_is_mutable<Iterator>:   Returns whether the given iterator is read-only or mutable
+ - \p is_iterator_adaptor<Iterator>:   Returns whether the given iterator is an adaptor over another iterator. See IteratorAdaptorConcept for additional requirements of adaptors.
+
+ \code
+concept PixelIteratorConcept<typename Iterator> : boost_concepts::RandomAccessTraversalConcept<Iterator>, PixelBasedConcept<Iterator> {
+    where PixelValueConcept<value_type>;
+    typename const_iterator_type<It>::type;         
+        where PixelIteratorConcept<const_iterator_type<It>::type>;
+    static const bool  iterator_is_mutable<It>::type::value;          
+    static const bool  is_iterator_adaptor<It>::type::value;   // is it an iterator adaptor
+};
+\endcode
+*/
+template <typename Iterator>
+struct PixelIteratorConcept {   
+    void constraints() {
+        gil_function_requires<boost_concepts::RandomAccessTraversalConcept<Iterator> >();
+        gil_function_requires<PixelBasedConcept<Iterator> >();
+        
+        typedef typename std::iterator_traits<Iterator>::value_type value_type;
+        gil_function_requires<PixelValueConcept<value_type> >();
+ 
+        typedef typename const_iterator_type<Iterator>::type const_t;
+        static const bool is_mut = iterator_is_mutable<Iterator>::type::value; ignore_unused_variable_warning(is_mut);
+
+        const_t const_it(it);  ignore_unused_variable_warning(const_it);  // immutable iterator must be constructible from (possibly mutable) iterator
+
+        check_base(typename is_iterator_adaptor<Iterator>::type());
+    }
+    void check_base(mpl::false_) {}
+    void check_base(mpl::true_) {
+        typedef typename iterator_adaptor_get_base<Iterator>::type base_t;
+        gil_function_requires<PixelIteratorConcept<base_t> >();
+    }
+
+    Iterator it;
+};
+
+namespace detail {
+    template <typename Iterator>  // Preconditions: Iterator Models PixelIteratorConcept
+    struct PixelIteratorIsMutableConcept {
+        void constraints() {
+            gil_function_requires<detail::RandomAccessIteratorIsMutableConcept<Iterator> >();
+            typedef typename remove_reference<typename std::iterator_traits<Iterator>::reference>::type ref;
+            typedef typename element_type<ref>::type channel_t;
+            gil_function_requires<detail::ChannelIsMutableConcept<channel_t> >();
+        }
+    };
+}
+
+/// \brief Pixel iterator that allows for changing its pixel
+/// \ingroup PixelIteratorConceptPixelIterator
+/**
+\code
+concept MutablePixelIteratorConcept<PixelIteratorConcept Iterator> : MutableRandomAccessIteratorConcept<Iterator> {};
+
+\endcode
+*/
+template <typename Iterator>
+struct MutablePixelIteratorConcept {
+    void constraints() {
+        gil_function_requires<PixelIteratorConcept<Iterator> >();
+        gil_function_requires<detail::PixelIteratorIsMutableConcept<Iterator> >();
+    }
+};
+
+namespace detail {
+    // Iterators that can be used as the base of memory_based_step_iterator require some additional functions
+    template <typename Iterator>  // Preconditions: Iterator Models boost_concepts::RandomAccessTraversalConcept
+    struct RandomAccessIteratorIsMemoryBasedConcept {
+        void constraints() {
+            std::ptrdiff_t bs=memunit_step(it);  ignore_unused_variable_warning(bs);
+            it=memunit_advanced(it,3);
+            std::ptrdiff_t bd=memunit_distance(it,it);  ignore_unused_variable_warning(bd);
+            memunit_advance(it,3);
+            // for performace you may also provide a customized implementation of memunit_advanced_ref
+        }
+        Iterator it;
+    };
+}
+
+/// \defgroup PixelIteratorConceptStepIterator StepIteratorConcept
+/// \ingroup PixelIteratorConcept
+/// \brief Iterator that advances by a specified step
+
+/// \brief Concept of a random-access iterator that can be advanced in memory units (bytes or bits)
+/// \ingroup PixelIteratorConceptStepIterator
+/**
+\code
+concept MemoryBasedIteratorConcept<boost_concepts::RandomAccessTraversalConcept Iterator> {
+    typename byte_to_memunit<Iterator>; where metafunction<byte_to_memunit<Iterator> >;
+    std::ptrdiff_t      memunit_step(const Iterator&);
+    std::ptrdiff_t      memunit_distance(const Iterator& , const Iterator&);
+    void                memunit_advance(Iterator&, std::ptrdiff_t diff);
+    Iterator            memunit_advanced(const Iterator& p, std::ptrdiff_t diff) { Iterator tmp; memunit_advance(tmp,diff); return tmp; }
+    Iterator::reference memunit_advanced_ref(const Iterator& p, std::ptrdiff_t diff) { return *memunit_advanced(p,diff); }
+};
+\endcode
+*/
+template <typename Iterator>
+struct MemoryBasedIteratorConcept {
+    void constraints() {
+        gil_function_requires<boost_concepts::RandomAccessTraversalConcept<Iterator> >();
+        gil_function_requires<detail::RandomAccessIteratorIsMemoryBasedConcept<Iterator> >();
+    }
+};
+
+/// \brief Step iterator concept
+///
+/// Step iterators are iterators that have a set_step method
+/// \ingroup PixelIteratorConceptStepIterator
+/**
+\code
+concept StepIteratorConcept<boost_concepts::ForwardTraversalConcept Iterator> {
+    template <Integral D> void Iterator::set_step(D step);
+};
+\endcode
+*/
+template <typename Iterator>
+struct StepIteratorConcept {
+    void constraints() {
+        gil_function_requires<boost_concepts::ForwardTraversalConcept<Iterator> >();
+        it.set_step(0);
+    }
+    Iterator it;
+};
+
+
+/// \brief Step iterator that allows for modifying its current value
+///
+/// \ingroup PixelIteratorConceptStepIterator
+/**
+\code
+concept MutableStepIteratorConcept<Mutable_ForwardIteratorConcept Iterator> : StepIteratorConcept<Iterator> {};
+\endcode
+*/
+template <typename Iterator>
+struct MutableStepIteratorConcept {
+    void constraints() {
+        gil_function_requires<StepIteratorConcept<Iterator> >();
+        gil_function_requires<detail::ForwardIteratorIsMutableConcept<Iterator> >();
+    }
+};
+
+/// \defgroup PixelIteratorConceptIteratorAdaptor IteratorAdaptorConcept
+/// \ingroup PixelIteratorConcept
+/// \brief Adaptor over another iterator
+
+/// \ingroup PixelIteratorConceptIteratorAdaptor
+/// \brief Iterator adaptor is a forward iterator adapting another forward iterator.
+/**
+In addition to GIL iterator requirements, GIL iterator adaptors must provide the following metafunctions:
+ - \p is_iterator_adaptor<Iterator>:             Returns \p mpl::true_
+ - \p iterator_adaptor_get_base<Iterator>:       Returns the base iterator type
+ - \p iterator_adaptor_rebind<Iterator,NewBase>: Replaces the base iterator with the new one
+
+The adaptee can be obtained from the iterator via the "base()" method.
+
+\code
+concept IteratorAdaptorConcept<boost_concepts::ForwardTraversalConcept Iterator> {
+    where SameType<is_iterator_adaptor<Iterator>::type, mpl::true_>;
+
+    typename iterator_adaptor_get_base<Iterator>;
+        where Metafunction<iterator_adaptor_get_base<Iterator> >;
+        where boost_concepts::ForwardTraversalConcept<iterator_adaptor_get_base<Iterator>::type>;
+    
+    typename another_iterator; 
+    typename iterator_adaptor_rebind<Iterator,another_iterator>::type;
+        where boost_concepts::ForwardTraversalConcept<another_iterator>;
+        where IteratorAdaptorConcept<iterator_adaptor_rebind<Iterator,another_iterator>::type>;
+
+    const iterator_adaptor_get_base<Iterator>::type& Iterator::base() const;
+};
+\endcode
+*/
+template <typename Iterator>
+struct IteratorAdaptorConcept {
+    void constraints() {
+        gil_function_requires<boost_concepts::ForwardTraversalConcept<Iterator> >();
+
+        typedef typename iterator_adaptor_get_base<Iterator>::type base_t;
+        gil_function_requires<boost_concepts::ForwardTraversalConcept<base_t> >();
+
+        BOOST_STATIC_ASSERT(is_iterator_adaptor<Iterator>::value);
+        typedef typename iterator_adaptor_rebind<Iterator, void*>::type rebind_t;
+
+        base_t base=it.base();  ignore_unused_variable_warning(base);
+    }
+    Iterator it;
+};
+
+/// \brief Iterator adaptor that is mutable
+/// \ingroup PixelIteratorConceptIteratorAdaptor
+/**
+\code
+concept MutableIteratorAdaptorConcept<Mutable_ForwardIteratorConcept Iterator> : IteratorAdaptorConcept<Iterator> {};
+\endcode
+*/
+template <typename Iterator>
+struct MutableIteratorAdaptorConcept {
+    void constraints() {
+        gil_function_requires<IteratorAdaptorConcept<Iterator> >();
+        gil_function_requires<detail::ForwardIteratorIsMutableConcept<Iterator> >();
+    }
+};
+
+////////////////////////////////////////////////////////////////////////////////////////
+///
+///         LOCATOR CONCEPTS
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \defgroup LocatorNDConcept RandomAccessNDLocatorConcept
+/// \ingroup PixelLocatorConcept
+/// \brief N-dimensional locator
+
+/// \defgroup Locator2DConcept RandomAccess2DLocatorConcept
+/// \ingroup PixelLocatorConcept
+/// \brief 2-dimensional locator
+
+/// \defgroup PixelLocator2DConcept PixelLocatorConcept
+/// \ingroup PixelLocatorConcept
+/// \brief 2-dimensional locator over pixel data
+
+/// \ingroup LocatorNDConcept
+/// \brief N-dimensional locator over immutable values
+/**
+\code
+concept RandomAccessNDLocatorConcept<Regular Loc> {    
+    typename value_type;        // value over which the locator navigates
+    typename reference;         // result of dereferencing
+    typename difference_type; where PointNDConcept<difference_type>; // return value of operator-.
+    typename const_t;           // same as Loc, but operating over immutable values
+    typename cached_location_t; // type to store relative location (for efficient repeated access)
+    typename point_t  = difference_type;
+    
+    static const size_t num_dimensions; // dimensionality of the locator
+    where num_dimensions = point_t::num_dimensions;
+    
+    // The difference_type and iterator type along each dimension. The iterators may only differ in 
+    // difference_type. Their value_type must be the same as Loc::value_type
+    template <size_t D> struct axis {
+        typename coord_t = point_t::axis<D>::coord_t;
+        typename iterator; where RandomAccessTraversalConcept<iterator>; // iterator along D-th axis.
+        where iterator::value_type == value_type;
+    };
+
+    // Defines the type of a locator similar to this type, except it invokes Deref upon dereferencing
+    template <PixelDereferenceAdaptorConcept Deref> struct add_deref {
+        typename type;        where RandomAccessNDLocatorConcept<type>;
+        static type make(const Loc& loc, const Deref& deref);
+    };
+    
+    Loc& operator+=(Loc&, const difference_type&);
+    Loc& operator-=(Loc&, const difference_type&);
+    Loc operator+(const Loc&, const difference_type&);
+    Loc operator-(const Loc&, const difference_type&);
+    
+    reference operator*(const Loc&);
+    reference operator[](const Loc&, const difference_type&);
+ 
+    // Storing relative location for faster repeated access and accessing it   
+    cached_location_t Loc::cache_location(const difference_type&) const;
+    reference operator[](const Loc&,const cached_location_t&);
+    
+    // Accessing iterators along a given dimension at the current location or at a given offset
+    template <size_t D> axis<D>::iterator&       Loc::axis_iterator();
+    template <size_t D> axis<D>::iterator const& Loc::axis_iterator() const;
+    template <size_t D> axis<D>::iterator        Loc::axis_iterator(const difference_type&) const;
+};
+\endcode
+*/
+template <typename Loc>
+struct RandomAccessNDLocatorConcept {
+    void constraints() {
+        gil_function_requires< Regular<Loc> >();
+
+        typedef typename Loc::value_type        value_type;
+        typedef typename Loc::reference         reference;          // result of dereferencing
+        typedef typename Loc::difference_type   difference_type;    // result of operator-(pixel_locator, pixel_locator)
+        typedef typename Loc::cached_location_t cached_location_t;  // type used to store relative location (to allow for more efficient repeated access)
+        typedef typename Loc::const_t           const_t;         // same as this type, but over const values
+        typedef typename Loc::point_t           point_t;         // same as difference_type
+        static const std::size_t N=Loc::num_dimensions; ignore_unused_variable_warning(N);
+    
+        typedef typename Loc::template axis<0>::iterator    first_it_type;
+        typedef typename Loc::template axis<N-1>::iterator  last_it_type;
+        gil_function_requires<boost_concepts::RandomAccessTraversalConcept<first_it_type> >();
+        gil_function_requires<boost_concepts::RandomAccessTraversalConcept<last_it_type> >();
+
+        // point_t must be an N-dimensional point, each dimension of which must have the same type as difference_type of the corresponding iterator
+        gil_function_requires<PointNDConcept<point_t> >();
+        BOOST_STATIC_ASSERT(point_t::num_dimensions==N);
+        BOOST_STATIC_ASSERT((is_same<typename std::iterator_traits<first_it_type>::difference_type, typename point_t::template axis<0>::coord_t>::value));
+        BOOST_STATIC_ASSERT((is_same<typename std::iterator_traits<last_it_type>::difference_type, typename point_t::template axis<N-1>::coord_t>::value));
+
+        difference_type d;
+        loc+=d;
+        loc-=d;
+        loc=loc+d;
+        loc=loc-d;
+        reference r1=loc[d];  ignore_unused_variable_warning(r1);
+        reference r2=*loc;  ignore_unused_variable_warning(r2);
+        cached_location_t cl=loc.cache_location(d);  ignore_unused_variable_warning(cl);
+        reference r3=loc[d];  ignore_unused_variable_warning(r3);
+
+        first_it_type fi=loc.template axis_iterator<0>();
+        fi=loc.template axis_iterator<0>(d);
+        last_it_type li=loc.template axis_iterator<N-1>();
+        li=loc.template axis_iterator<N-1>(d);
+
+        typedef PixelDereferenceAdaptorArchetype<typename Loc::value_type> deref_t;
+        typedef typename Loc::template add_deref<deref_t>::type dtype;
+        //gil_function_requires<RandomAccessNDLocatorConcept<dtype> >();    // infinite recursion
+    }
+    Loc loc;
+};
+
+/// \ingroup Locator2DConcept
+/// \brief 2-dimensional locator over immutable values
+/**
+\code
+concept RandomAccess2DLocatorConcept<RandomAccessNDLocatorConcept Loc> {
+    where num_dimensions==2;
+    where Point2DConcept<point_t>;
+    
+    typename x_iterator = axis<0>::iterator;
+    typename y_iterator = axis<1>::iterator;
+    typename x_coord_t  = axis<0>::coord_t;
+    typename y_coord_t  = axis<1>::coord_t;
+    
+    // Only available to locators that have dynamic step in Y
+    //Loc::Loc(const Loc& loc, y_coord_t);
+
+    // Only available to locators that have dynamic step in X and Y
+    //Loc::Loc(const Loc& loc, x_coord_t, y_coord_t, bool transposed=false);
+
+    x_iterator&       Loc::x();
+    x_iterator const& Loc::x() const;    
+    y_iterator&       Loc::y();
+    y_iterator const& Loc::y() const;    
+    
+    x_iterator Loc::x_at(const difference_type&) const;
+    y_iterator Loc::y_at(const difference_type&) const;
+    Loc Loc::xy_at(const difference_type&) const;
+    
+    // x/y versions of all methods that can take difference type
+    x_iterator        Loc::x_at(x_coord_t, y_coord_t) const;
+    y_iterator        Loc::y_at(x_coord_t, y_coord_t) const;
+    Loc               Loc::xy_at(x_coord_t, y_coord_t) const;
+    reference         operator()(const Loc&, x_coord_t, y_coord_t);
+    cached_location_t Loc::cache_location(x_coord_t, y_coord_t) const;
+
+    bool      Loc::is_1d_traversable(x_coord_t width) const;
+    y_coord_t Loc::y_distance_to(const Loc& loc2, x_coord_t x_diff) const;
+};
+\endcode
+*/
+template <typename Loc>
+struct RandomAccess2DLocatorConcept {
+    void constraints() {
+        gil_function_requires<RandomAccessNDLocatorConcept<Loc> >();
+        BOOST_STATIC_ASSERT(Loc::num_dimensions==2);
+
+        typedef typename dynamic_x_step_type<Loc>::type dynamic_x_step_t;
+        typedef typename dynamic_y_step_type<Loc>::type dynamic_y_step_t;
+        typedef typename transposed_type<Loc>::type     transposed_t;
+
+        typedef typename Loc::cached_location_t   cached_location_t;
+        gil_function_requires<Point2DConcept<typename Loc::point_t> >();
+
+        typedef typename Loc::x_iterator x_iterator;
+        typedef typename Loc::y_iterator y_iterator;
+        typedef typename Loc::x_coord_t  x_coord_t;
+        typedef typename Loc::y_coord_t  y_coord_t;
+
+        x_coord_t xd=0; ignore_unused_variable_warning(xd);
+        y_coord_t yd=0; ignore_unused_variable_warning(yd);
+
+        typename Loc::difference_type d;
+        typename Loc::reference r=loc(xd,yd);  ignore_unused_variable_warning(r);
+
+        dynamic_x_step_t loc2(dynamic_x_step_t(), yd);
+        dynamic_x_step_t loc3(dynamic_x_step_t(), xd, yd);
+
+        typedef typename dynamic_y_step_type<typename dynamic_x_step_type<transposed_t>::type>::type dynamic_xy_step_transposed_t;
+        dynamic_xy_step_transposed_t loc4(loc, xd,yd,true);
+
+        bool is_contiguous=loc.is_1d_traversable(xd); ignore_unused_variable_warning(is_contiguous);
+        loc.y_distance_to(loc, xd);
+
+        loc=loc.xy_at(d);
+        loc=loc.xy_at(xd,yd);
+
+        x_iterator xit=loc.x_at(d);
+        xit=loc.x_at(xd,yd);
+        xit=loc.x();
+
+        y_iterator yit=loc.y_at(d);
+        yit=loc.y_at(xd,yd);
+        yit=loc.y();
+
+        cached_location_t cl=loc.cache_location(xd,yd);  ignore_unused_variable_warning(cl);
+    }
+    Loc loc;
+};
+
+/// \ingroup PixelLocator2DConcept
+/// \brief GIL's 2-dimensional locator over immutable GIL pixels
+/**
+\code
+concept PixelLocatorConcept<RandomAccess2DLocatorConcept Loc> {
+    where PixelValueConcept<value_type>;
+    where PixelIteratorConcept<x_iterator>;
+    where PixelIteratorConcept<y_iterator>;
+    where x_coord_t == y_coord_t;
+
+    typename coord_t = x_coord_t;
+};
+\endcode
+*/
+template <typename Loc>
+struct PixelLocatorConcept {
+    void constraints() {
+        gil_function_requires< RandomAccess2DLocatorConcept<Loc> >();
+        gil_function_requires< PixelIteratorConcept<typename Loc::x_iterator> >();
+        gil_function_requires< PixelIteratorConcept<typename Loc::y_iterator> >();
+        typedef typename Loc::coord_t                      coord_t;
+        BOOST_STATIC_ASSERT((is_same<typename Loc::x_coord_t, typename Loc::y_coord_t>::value));
+    }
+    Loc loc;
+};
+
+namespace detail {
+    template <typename Loc> // preconditions: Loc Models RandomAccessNDLocatorConcept
+    struct RandomAccessNDLocatorIsMutableConcept {
+        void constraints() {
+            gil_function_requires<detail::RandomAccessIteratorIsMutableConcept<typename Loc::template axis<0>::iterator> >();
+            gil_function_requires<detail::RandomAccessIteratorIsMutableConcept<typename Loc::template axis<Loc::num_dimensions-1>::iterator> >();
+
+            typename Loc::difference_type d; initialize_it(d);
+            typename Loc::value_type v;initialize_it(v);
+            typename Loc::cached_location_t cl=loc.cache_location(d);
+            *loc=v;
+            loc[d]=v;
+            loc[cl]=v;
+        }
+        Loc loc;
+    };
+
+    template <typename Loc> // preconditions: Loc Models RandomAccess2DLocatorConcept
+    struct RandomAccess2DLocatorIsMutableConcept {
+        void constraints() {
+            gil_function_requires<detail::RandomAccessNDLocatorIsMutableConcept<Loc> >();
+            typename Loc::x_coord_t xd=0; ignore_unused_variable_warning(xd);
+            typename Loc::y_coord_t yd=0; ignore_unused_variable_warning(yd);
+            typename Loc::value_type v; initialize_it(v);
+            loc(xd,yd)=v;
+        }
+        Loc loc;
+    };
+}
+
+/// \ingroup LocatorNDConcept
+/// \brief N-dimensional locator over mutable pixels
+/**
+\code
+concept MutableRandomAccessNDLocatorConcept<RandomAccessNDLocatorConcept Loc> {    
+    where Mutable<reference>;
+};
+\endcode
+*/
+template <typename Loc>
+struct MutableRandomAccessNDLocatorConcept {
+    void constraints() {
+        gil_function_requires<RandomAccessNDLocatorConcept<Loc> >();
+        gil_function_requires<detail::RandomAccessNDLocatorIsMutableConcept<Loc> >();
+    }
+};
+
+/// \ingroup Locator2DConcept
+/// \brief 2-dimensional locator over mutable pixels
+/**
+\code
+concept MutableRandomAccess2DLocatorConcept<RandomAccess2DLocatorConcept Loc> : MutableRandomAccessNDLocatorConcept<Loc> {};
+\endcode
+*/
+template <typename Loc>
+struct MutableRandomAccess2DLocatorConcept {
+    void constraints() {
+        gil_function_requires< RandomAccess2DLocatorConcept<Loc> >();
+        gil_function_requires<detail::RandomAccess2DLocatorIsMutableConcept<Loc> >();
+    }
+};
+
+/// \ingroup PixelLocator2DConcept
+/// \brief GIL's 2-dimensional locator over mutable GIL pixels
+/**
+\code
+concept MutablePixelLocatorConcept<PixelLocatorConcept Loc> : MutableRandomAccess2DLocatorConcept<Loc> {};
+\endcode
+*/
+template <typename Loc>
+struct MutablePixelLocatorConcept {
+    void constraints() {
+        gil_function_requires<PixelLocatorConcept<Loc> >();
+        gil_function_requires<detail::RandomAccess2DLocatorIsMutableConcept<Loc> >();
+    }
+};
+
+////////////////////////////////////////////////////////////////////////////////////////
+///
+///         IMAGE VIEW CONCEPTS
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+/// \defgroup ImageViewNDConcept ImageViewNDLocatorConcept
+/// \ingroup ImageViewConcept
+/// \brief N-dimensional range
+
+/// \defgroup ImageView2DConcept ImageView2DConcept
+/// \ingroup ImageViewConcept
+/// \brief 2-dimensional range
+
+/// \defgroup PixelImageViewConcept ImageViewConcept
+/// \ingroup ImageViewConcept
+/// \brief 2-dimensional range over pixel data
+
+/// \ingroup ImageViewNDConcept
+/// \brief N-dimensional view over immutable values
+/**
+\code
+concept RandomAccessNDImageViewConcept<Regular View> {
+    typename value_type;
+    typename reference;       // result of dereferencing
+    typename difference_type; // result of operator-(iterator,iterator) (1-dimensional!)
+    typename const_t;  where RandomAccessNDImageViewConcept<View>; // same as View, but over immutable values
+    typename point_t;  where PointNDConcept<point_t>; // N-dimensional point
+    typename locator;  where RandomAccessNDLocatorConcept<locator>; // N-dimensional locator.
+    typename iterator; where RandomAccessTraversalConcept<iterator>; // 1-dimensional iterator over all values
+    typename reverse_iterator; where RandomAccessTraversalConcept<reverse_iterator>; 
+    typename size_type;       // the return value of size()
+
+    // Equivalent to RandomAccessNDLocatorConcept::axis
+    template <size_t D> struct axis {
+        typename coord_t = point_t::axis<D>::coord_t;
+        typename iterator; where RandomAccessTraversalConcept<iterator>;   // iterator along D-th axis.
+        where SameType<coord_t, iterator::difference_type>;
+        where SameType<iterator::value_type,value_type>;
+    };
+
+    // Defines the type of a view similar to this type, except it invokes Deref upon dereferencing
+    template <PixelDereferenceAdaptorConcept Deref> struct add_deref {
+        typename type;        where RandomAccessNDImageViewConcept<type>;
+        static type make(const View& v, const Deref& deref);
+    };
+
+    static const size_t num_dimensions = point_t::num_dimensions;
+    
+    // Create from a locator at the top-left corner and dimensions
+    View::View(const locator&, const point_type&);
+    
+    size_type        View::size()       const; // total number of elements
+    reference        operator[](View, const difference_type&) const; // 1-dimensional reference
+    iterator         View::begin()      const;
+    iterator         View::end()        const;
+    reverse_iterator View::rbegin()     const;
+    reverse_iterator View::rend()       const;
+    iterator         View::at(const point_t&);
+    point_t          View::dimensions() const; // number of elements along each dimension
+    bool             View::is_1d_traversable() const;   // can an iterator over the first dimension visit each value? I.e. are there gaps between values?
+
+    // iterator along a given dimension starting at a given point
+    template <size_t D> View::axis<D>::iterator View::axis_iterator(const point_t&) const;
+
+    reference operator()(View,const point_t&) const;
+};
+\endcode
+*/
+template <typename View>
+struct RandomAccessNDImageViewConcept {
+    void constraints() {
+        gil_function_requires< Regular<View> >();
+
+        typedef typename View::value_type       value_type;
+        typedef typename View::reference        reference;       // result of dereferencing
+        typedef typename View::difference_type  difference_type; // result of operator-(1d_iterator,1d_iterator)
+        typedef typename View::const_t          const_t;         // same as this type, but over const values
+        typedef typename View::point_t          point_t;         // N-dimensional point
+        typedef typename View::locator          locator;         // N-dimensional locator
+        typedef typename View::iterator         iterator;
+        typedef typename View::reverse_iterator reverse_iterator;
+        typedef typename View::size_type        size_type;
+        static const std::size_t N=View::num_dimensions;
+    
+        gil_function_requires<RandomAccessNDLocatorConcept<locator> >();
+        gil_function_requires<boost_concepts::RandomAccessTraversalConcept<iterator> >();
+        gil_function_requires<boost_concepts::RandomAccessTraversalConcept<reverse_iterator> >();
+
+        typedef typename View::template axis<0>::iterator   first_it_type;
+        typedef typename View::template axis<N-1>::iterator last_it_type;
+        gil_function_requires<boost_concepts::RandomAccessTraversalConcept<first_it_type> >();
+        gil_function_requires<boost_concepts::RandomAccessTraversalConcept<last_it_type> >();
+
+//        BOOST_STATIC_ASSERT((typename std::iterator_traits<first_it_type>::difference_type, typename point_t::template axis<0>::coord_t>::value));
+//        BOOST_STATIC_ASSERT((typename std::iterator_traits< last_it_type>::difference_type, typename point_t::template axis<N-1>::coord_t>::value));
+
+        // point_t must be an N-dimensional point, each dimension of which must have the same type as difference_type of the corresponding iterator
+        gil_function_requires<PointNDConcept<point_t> >();
+        BOOST_STATIC_ASSERT(point_t::num_dimensions==N);
+        BOOST_STATIC_ASSERT((is_same<typename std::iterator_traits<first_it_type>::difference_type, typename point_t::template axis<0>::coord_t>::value));
+        BOOST_STATIC_ASSERT((is_same<typename std::iterator_traits<last_it_type>::difference_type, typename point_t::template axis<N-1>::coord_t>::value));
+
+        point_t p;
+        locator lc;
+        iterator it;
+        reverse_iterator rit;
+        difference_type d; detail::initialize_it(d); ignore_unused_variable_warning(d);
+
+        View(p,lc); // view must be constructible from a locator and a point
+
+        p=view.dimensions();
+        lc=view.pixels();
+        size_type sz=view.size();  ignore_unused_variable_warning(sz);
+        bool is_contiguous=view.is_1d_traversable(); ignore_unused_variable_warning(is_contiguous);
+
+        it=view.begin();
+        it=view.end();
+        rit=view.rbegin();
+        rit=view.rend();
+
+        reference r1=view[d]; ignore_unused_variable_warning(r1);    // 1D access 
+        reference r2=view(p); ignore_unused_variable_warning(r2);    // 2D access
+
+        // get 1-D iterator of any dimension at a given pixel location
+        first_it_type fi=view.template axis_iterator<0>(p); ignore_unused_variable_warning(fi);
+        last_it_type li=view.template axis_iterator<N-1>(p); ignore_unused_variable_warning(li);
+
+        typedef PixelDereferenceAdaptorArchetype<typename View::value_type> deref_t;
+        typedef typename View::template add_deref<deref_t>::type dtype;
+    }
+    View view;
+};
+
+/// \ingroup ImageView2DConcept
+/// \brief 2-dimensional view over immutable values
+/**
+\code
+concept RandomAccess2DImageViewConcept<RandomAccessNDImageViewConcept View> {
+    where num_dimensions==2;
+
+    typename x_iterator = axis<0>::iterator;
+    typename y_iterator = axis<1>::iterator;
+    typename x_coord_t  = axis<0>::coord_t;
+    typename y_coord_t  = axis<1>::coord_t;
+    typename xy_locator = locator;
+    
+    x_coord_t View::width()  const;
+    y_coord_t View::height() const;
+    
+    // X-navigation
+    x_iterator View::x_at(const point_t&) const;
+    x_iterator View::row_begin(y_coord_t) const;
+    x_iterator View::row_end  (y_coord_t) const;
+
+    // Y-navigation
+    y_iterator View::y_at(const point_t&) const;
+    y_iterator View::col_begin(x_coord_t) const;
+    y_iterator View::col_end  (x_coord_t) const;
+       
+    // navigating in 2D
+    xy_locator View::xy_at(const point_t&) const;
+
+    // (x,y) versions of all methods taking point_t    
+    View::View(x_coord_t,y_coord_t,const locator&);
+    iterator View::at(x_coord_t,y_coord_t) const;
+    reference operator()(View,x_coord_t,y_coord_t) const;
+    xy_locator View::xy_at(x_coord_t,y_coord_t) const;
+    x_iterator View::x_at(x_coord_t,y_coord_t) const;
+    y_iterator View::y_at(x_coord_t,y_coord_t) const;
+};
+\endcode
+*/
+template <typename View>
+struct RandomAccess2DImageViewConcept {
+    void constraints() {
+        gil_function_requires<RandomAccessNDImageViewConcept<View> >();
+        BOOST_STATIC_ASSERT(View::num_dimensions==2);
+
+        // TODO: This executes the requirements for RandomAccessNDLocatorConcept again. Fix it to improve compile time
+        gil_function_requires<RandomAccess2DLocatorConcept<typename View::locator> >();
+
+        typedef typename dynamic_x_step_type<View>::type  dynamic_x_step_t;
+        typedef typename dynamic_y_step_type<View>::type  dynamic_y_step_t;
+        typedef typename transposed_type<View>::type      transposed_t;
+
+        typedef typename View::x_iterator x_iterator;
+        typedef typename View::y_iterator y_iterator;
+        typedef typename View::x_coord_t  x_coord_t;
+        typedef typename View::y_coord_t  y_coord_t;
+        typedef typename View::xy_locator xy_locator;
+
+        x_coord_t xd=0; ignore_unused_variable_warning(xd);
+        y_coord_t yd=0; ignore_unused_variable_warning(yd);
+        x_iterator xit;
+        y_iterator yit;
+        typename View::point_t d;
+
+        View(xd,yd,xy_locator());       // constructible with width, height, 2d_locator
+
+        xy_locator lc=view.xy_at(xd,yd);
+        lc=view.xy_at(d);
+
+        typename View::reference r=view(xd,yd);  ignore_unused_variable_warning(r);
+        xd=view.width();
+        yd=view.height();
+
+        xit=view.x_at(d);
+        xit=view.x_at(xd,yd);
+        xit=view.row_begin(xd);
+        xit=view.row_end(xd);
+
+        yit=view.y_at(d);
+        yit=view.y_at(xd,yd);
+        yit=view.col_begin(xd);
+        yit=view.col_end(xd);
+    }
+    View view;
+};
+
+
+/// \ingroup PixelImageViewConcept
+/// \brief GIL's 2-dimensional view over immutable GIL pixels
+/**
+\code
+concept ImageViewConcept<RandomAccess2DImageViewConcept View> {
+    where PixelValueConcept<value_type>;
+    where PixelIteratorConcept<x_iterator>;        
+    where PixelIteratorConcept<y_iterator>;
+    where x_coord_t == y_coord_t;
+    
+    typename coord_t = x_coord_t;
+
+    std::size_t View::num_channels() const;
+};
+\endcode
+*/
+template <typename View>
+struct ImageViewConcept {
+    void constraints() {
+        gil_function_requires<RandomAccess2DImageViewConcept<View> >();
+
+        // TODO: This executes the requirements for RandomAccess2DLocatorConcept again. Fix it to improve compile time
+        gil_function_requires<PixelLocatorConcept<typename View::xy_locator> >();
+        
+        BOOST_STATIC_ASSERT((is_same<typename View::x_coord_t, typename View::y_coord_t>::value));
+
+        typedef typename View::coord_t           coord_t;      // 1D difference type (same for all dimensions)
+        std::size_t num_chan = view.num_channels(); ignore_unused_variable_warning(num_chan);
+    }
+    View view;
+};
+
+
+namespace detail {
+    template <typename View>    // Preconditions: View Models RandomAccessNDImageViewConcept
+    struct RandomAccessNDImageViewIsMutableConcept {
+        void constraints() {
+            gil_function_requires<detail::RandomAccessNDLocatorIsMutableConcept<typename View::locator> >();
+
+            gil_function_requires<detail::RandomAccessIteratorIsMutableConcept<typename View::iterator> >();
+            gil_function_requires<detail::RandomAccessIteratorIsMutableConcept<typename View::reverse_iterator> >();
+            gil_function_requires<detail::RandomAccessIteratorIsMutableConcept<typename View::template axis<0>::iterator> >();
+            gil_function_requires<detail::RandomAccessIteratorIsMutableConcept<typename View::template axis<View::num_dimensions-1>::iterator> >();
+
+            typename View::difference_type diff; initialize_it(diff); ignore_unused_variable_warning(diff);
+            typename View::point_t pt;
+            typename View::value_type v; initialize_it(v);
+
+            view[diff]=v;
+            view(pt)=v;
+        }
+        View view;
+    };
+
+    template <typename View>    // preconditions: View Models RandomAccessNDImageViewConcept
+    struct RandomAccess2DImageViewIsMutableConcept {
+        void constraints() {        
+            gil_function_requires<detail::RandomAccessNDImageViewIsMutableConcept<View> >();
+            typename View::x_coord_t xd=0; ignore_unused_variable_warning(xd);
+            typename View::y_coord_t yd=0; ignore_unused_variable_warning(yd);
+            typename View::value_type v; initialize_it(v);
+            view(xd,yd)=v;
+        }
+        View view;
+    };
+
+    template <typename View>    // preconditions: View Models ImageViewConcept
+    struct PixelImageViewIsMutableConcept {
+        void constraints() {        
+            gil_function_requires<detail::RandomAccess2DImageViewIsMutableConcept<View> >();
+        }
+    };
+}
+
+/// \ingroup ImageViewNDConcept
+/// \brief N-dimensional view over mutable values
+/**
+\code
+concept MutableRandomAccessNDImageViewConcept<RandomAccessNDImageViewConcept View> {
+    where Mutable<reference>;
+};
+\endcode
+*/
+template <typename View>
+struct MutableRandomAccessNDImageViewConcept {
+    void constraints() {
+        gil_function_requires<RandomAccessNDImageViewConcept<View> >();
+        gil_function_requires<detail::RandomAccessNDImageViewIsMutableConcept<View> >();
+    }
+};
+
+/// \ingroup ImageView2DConcept
+/// \brief 2-dimensional view over mutable values
+/**
+\code
+concept MutableRandomAccess2DImageViewConcept<RandomAccess2DImageViewConcept View> : MutableRandomAccessNDImageViewConcept<View> {};
+\endcode
+*/
+template <typename View>
+struct MutableRandomAccess2DImageViewConcept {
+    void constraints() {
+        gil_function_requires<RandomAccess2DImageViewConcept<View> >();
+        gil_function_requires<detail::RandomAccess2DImageViewIsMutableConcept<View> >();
+    }
+};
+
+/// \ingroup PixelImageViewConcept
+/// \brief GIL's 2-dimensional view over mutable GIL pixels
+/**
+\code
+concept MutableImageViewConcept<ImageViewConcept View> : MutableRandomAccess2DImageViewConcept<View> {};
+\endcode
+*/
+template <typename View>
+struct MutableImageViewConcept {
+    void constraints() {
+        gil_function_requires<ImageViewConcept<View> >();
+        gil_function_requires<detail::PixelImageViewIsMutableConcept<View> >();
+    }
+};
+
+/// \brief Returns whether two views are compatible
+///
+/// Views are compatible if their pixels are compatible. Compatible views can be assigned and copy constructed from one another.
+template <typename V1, typename V2>  // Model ImageViewConcept
+struct views_are_compatible : public pixels_are_compatible<typename V1::value_type, typename V2::value_type> {};
+
+/// \brief Views are compatible if they have the same color spaces and compatible channel values. Constness and layout are not important for compatibility
+/// \ingroup ImageViewConcept
+/**
+\code
+concept ViewsCompatibleConcept<ImageViewConcept V1, ImageViewConcept V2> {
+    where PixelsCompatibleConcept<V1::value_type, P2::value_type>;
+};
+\endcode
+*/
+template <typename V1, typename V2>
+struct ViewsCompatibleConcept {
+    void constraints() {
+        BOOST_STATIC_ASSERT((views_are_compatible<V1,V2>::value));
+    }
+};
+
+
+////////////////////////////////////////////////////////////////////////////////////////
+///
+///         IMAGE CONCEPTS
+///
+////////////////////////////////////////////////////////////////////////////////////////
+
+
+/// \ingroup ImageConcept
+/// \brief N-dimensional container of values
+/**
+\code
+concept RandomAccessNDImageConcept<typename Img> : Regular<Img> {
+    typename view_t; where MutableRandomAccessNDImageViewConcept<view_t>;
+    typename const_view_t = view_t::const_t;
+    typename point_t      = view_t::point_t;
+    typename value_type   = view_t::value_type;
+    typename allocator_type;
+
+    Img::Img(point_t dims, std::size_t alignment=1);
+    Img::Img(point_t dims, value_type fill_value, std::size_t alignment);
+    
+    void Img::recreate(point_t new_dims, std::size_t alignment=1);
+    void Img::recreate(point_t new_dims, value_type fill_value, std::size_t alignment);
+
+    const point_t&        Img::dimensions() const;
+    const const_view_t&   const_view(const Img&);
+    const view_t&         view(Img&);
+};
+\endcode
+*/
+template <typename Img>
+struct RandomAccessNDImageConcept {
+    void constraints() {
+        gil_function_requires<Regular<Img> >();
+
+        typedef typename Img::view_t       view_t;
+        gil_function_requires<MutableRandomAccessNDImageViewConcept<view_t> >();
+
+        typedef typename Img::const_view_t const_view_t;
+        typedef typename Img::value_type   pixel_t;
+
+        typedef typename Img::point_t        point_t;
+        gil_function_requires<PointNDConcept<point_t> >();
+
+        const_view_t cv = const_view(img); ignore_unused_variable_warning(cv);
+        view_t       v  = view(img);       ignore_unused_variable_warning(v);
+
+        pixel_t fill_value;
+        point_t pt=img.dimensions();
+        Img im1(pt);
+        Img im2(pt,1);
+        Img im3(pt,fill_value,1);
+        img.recreate(pt);
+        img.recreate(pt,1);
+        img.recreate(pt,fill_value,1);
+    }
+    Img img;
+};
+
+
+/// \ingroup ImageConcept
+/// \brief 2-dimensional container of values
+/**
+\code
+concept RandomAccess2DImageConcept<RandomAccessNDImageConcept Img> {
+    typename x_coord_t = const_view_t::x_coord_t;
+    typename y_coord_t = const_view_t::y_coord_t;
+    
+    Img::Img(x_coord_t width, y_coord_t height, std::size_t alignment=1);
+    Img::Img(x_coord_t width, y_coord_t height, value_type fill_value, std::size_t alignment);
+
+    x_coord_t Img::width() const;
+    y_coord_t Img::height() const;
+    
+    void Img::recreate(x_coord_t width, y_coord_t height, std::size_t alignment=1);
+    void Img::recreate(x_coord_t width, y_coord_t height, value_type fill_value, std::size_t alignment);
+};
+\endcode
+*/
+template <typename Img>
+struct RandomAccess2DImageConcept {
+    void constraints() {
+        gil_function_requires<RandomAccessNDImageConcept<Img> >();
+        typedef typename Img::x_coord_t  x_coord_t;
+        typedef typename Img::y_coord_t  y_coord_t;
+        typedef typename Img::value_type value_t;
+
+        gil_function_requires<MutableRandomAccess2DImageViewConcept<typename Img::view_t> >();
+
+        x_coord_t w=img.width();
+        y_coord_t h=img.height();
+        value_t fill_value;
+        Img im1(w,h);
+        Img im2(w,h,1);
+        Img im3(w,h,fill_value,1);
+        img.recreate(w,h);
+        img.recreate(w,h,1);
+        img.recreate(w,h,fill_value,1);
+    }
+    Img img;
+};
+
+/// \ingroup ImageConcept
+/// \brief 2-dimensional image whose value type models PixelValueConcept
+/**
+\code 
+concept ImageConcept<RandomAccess2DImageConcept Img> {
+    where MutableImageViewConcept<view_t>;
+    typename coord_t  = view_t::coord_t;
+};
+\endcode
+*/
+template <typename Img>
+struct ImageConcept {
+    void constraints() {
+        gil_function_requires<RandomAccess2DImageConcept<Img> >();
+        gil_function_requires<MutableImageViewConcept<typename Img::view_t> >();
+        typedef typename Img::coord_t        coord_t;
+        BOOST_STATIC_ASSERT(num_channels<Img>::value == mpl::size<typename color_space_type<Img>::type>::value);
+
+        BOOST_STATIC_ASSERT((is_same<coord_t, typename Img::x_coord_t>::value));
+        BOOST_STATIC_ASSERT((is_same<coord_t, typename Img::y_coord_t>::value));
+    }
+    Img img;
+};
+
+
+} }  // namespace boost::gil
+
+#endif