    // Copyright (C) 2015  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_DNn_INPUT_H_
    #define DLIB_DNn_INPUT_H_

    #include "input_abstract.h"
    #include "../matrix.h"
    #include "../array2d.h"
    #include "../pixel.h"
    #include "../image_processing.h"
    #include <sstream>
    #include <array>
    #include "../cuda/tensor_tools.h"

    namespace dlib
    {

    // ----------------------------------------------------------------------------------------

        template <typename T>
        class input
        {
            const static bool always_false = sizeof(T)!=sizeof(T);
            static_assert(always_false, "Unsupported type given to input<>.  input<> only supports "
                "dlib::matrix and dlib::array2d objects.");
        };

    // ----------------------------------------------------------------------------------------

        template <size_t NR, size_t NC=NR>
        class input_rgb_image_sized;

        class input_rgb_image_pair;

        class input_rgb_image
        {
        public:
            typedef matrix<rgb_pixel> input_type;

            input_rgb_image (
            ) :
                avg_red(122.782f),
                avg_green(117.001f),
                avg_blue(104.298f)
            {
            }

            input_rgb_image (
                float avg_red_,
                float avg_green_,
                float avg_blue_
            ) : avg_red(avg_red_), avg_green(avg_green_), avg_blue(avg_blue_)
            {}

            template <size_t NR, size_t NC>
            inline input_rgb_image (
                const input_rgb_image_sized<NR,NC>& item
            );

            inline input_rgb_image (
                const input_rgb_image_pair& item
            );

            float get_avg_red()   const { return avg_red; }
            float get_avg_green() const { return avg_green; }
            float get_avg_blue()  const { return avg_blue; }

            bool image_contained_point ( const tensor& data, const point& p) const { return get_rect(data).contains(p); }
            drectangle tensor_space_to_image_space ( const tensor& /*data*/, drectangle r) const { return r; }
            drectangle image_space_to_tensor_space ( const tensor& /*data*/, double /*scale*/, drectangle r ) const { return r; }

            template <typename forward_iterator>
            void to_tensor (
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                DLIB_CASSERT(std::distance(ibegin,iend) > 0);
                const auto nr = ibegin->nr();
                const auto nc = ibegin->nc();
                // make sure all the input matrices have the same dimensions
                for (auto i = ibegin; i != iend; ++i)
                {
                    DLIB_CASSERT(i->nr()==nr && i->nc()==nc,
                        "\t input_rgb_image::to_tensor()"
                        << "\n\t All matrices given to to_tensor() must have the same dimensions."
                        << "\n\t nr: " << nr
                        << "\n\t nc: " << nc
                        << "\n\t i->nr(): " << i->nr()
                        << "\n\t i->nc(): " << i->nc()
                    );
                }

                // initialize data to the right size to contain the stuff in the iterator range.
                data.set_size(std::distance(ibegin,iend), 3, nr, nc);

                const size_t offset = nr*nc;
                auto ptr = data.host();
                for (auto i = ibegin; i != iend; ++i)
                {
                    for (long r = 0; r < nr; ++r)
                    {
                        for (long c = 0; c < nc; ++c)
                        {
                            rgb_pixel temp = (*i)(r,c);
                            auto p = ptr++;
                            *p = (temp.red-avg_red)/256.0;
                            p += offset;
                            *p = (temp.green-avg_green)/256.0;
                            p += offset;
                            *p = (temp.blue-avg_blue)/256.0;
                            p += offset;
                        }
                    }
                    ptr += offset*(data.k()-1);
                }

            }

            friend void serialize(const input_rgb_image& item, std::ostream& out)
            {
                serialize("input_rgb_image", out);
                serialize(item.avg_red, out);
                serialize(item.avg_green, out);
                serialize(item.avg_blue, out);
            }

            friend void deserialize(input_rgb_image& item, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input_rgb_image" && version != "input_rgb_image_sized" && version != "input_rgb_image_pair")
                    throw serialization_error("Unexpected version found while deserializing dlib::input_rgb_image.");
                deserialize(item.avg_red, in);
                deserialize(item.avg_green, in);
                deserialize(item.avg_blue, in);

                // read and discard the sizes if this was really a sized input layer.
                if (version == "input_rgb_image_sized")
                {
                    size_t nr, nc;
                    deserialize(nr, in);
                    deserialize(nc, in);
                }
            }

            friend std::ostream& operator<<(std::ostream& out, const input_rgb_image& item)
            {
                out << "input_rgb_image("<<item.avg_red<<","<<item.avg_green<<","<<item.avg_blue<<")";
                return out;
            }

            friend void to_xml(const input_rgb_image& item, std::ostream& out)
            {
                out << "<input_rgb_image r='"<<item.avg_red<<"' g='"<<item.avg_green<<"' b='"<<item.avg_blue<<"'/>\n";
            }

        private:
            float avg_red;
            float avg_green;
            float avg_blue;
        };

    // ----------------------------------------------------------------------------------------

        template <size_t NR, size_t NC>
        class input_rgb_image_sized
        {
        public:
            static_assert(NR != 0 && NC != 0, "The input image can't be empty.");

            typedef matrix<rgb_pixel> input_type;

            input_rgb_image_sized (
            ) :
                avg_red(122.782),
                avg_green(117.001),
                avg_blue(104.298)
            {
            }

            input_rgb_image_sized (
                const input_rgb_image& item
            ) : avg_red(item.get_avg_red()),
                avg_green(item.get_avg_green()),
                avg_blue(item.get_avg_blue())
            {}

            input_rgb_image_sized (
                float avg_red_,
                float avg_green_,
                float avg_blue_
            ) : avg_red(avg_red_), avg_green(avg_green_), avg_blue(avg_blue_)
            {}

            float get_avg_red()   const { return avg_red; }
            float get_avg_green() const { return avg_green; }
            float get_avg_blue()  const { return avg_blue; }

            bool image_contained_point ( const tensor& data, const point& p) const { return get_rect(data).contains(p); }
            drectangle tensor_space_to_image_space ( const tensor& /*data*/, drectangle r) const { return r; }
            drectangle image_space_to_tensor_space ( const tensor& /*data*/, double /*scale*/, drectangle r ) const { return r; }

            template <typename forward_iterator>
            void to_tensor (
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                DLIB_CASSERT(std::distance(ibegin,iend) > 0);
                // make sure all input images have the correct size
                for (auto i = ibegin; i != iend; ++i)
                {
                    DLIB_CASSERT(i->nr()==NR && i->nc()==NC,
                        "\t input_rgb_image_sized::to_tensor()"
                        << "\n\t All input images must have "<<NR<<" rows and "<<NC<< " columns, but we got one with "<<i->nr()<<" rows and "<<i->nc()<<" columns."
                    );
                }

                // initialize data to the right size to contain the stuff in the iterator range.
                data.set_size(std::distance(ibegin,iend), 3, NR, NC);

                const size_t offset = NR*NC;
                auto ptr = data.host();
                for (auto i = ibegin; i != iend; ++i)
                {
                    for (size_t r = 0; r < NR; ++r)
                    {
                        for (size_t c = 0; c < NC; ++c)
                        {
                            rgb_pixel temp = (*i)(r,c);
                            auto p = ptr++;
                            *p = (temp.red-avg_red)/256.0;
                            p += offset;
                            *p = (temp.green-avg_green)/256.0;
                            p += offset;
                            *p = (temp.blue-avg_blue)/256.0;
                            p += offset;
                        }
                    }
                    ptr += offset*(data.k()-1);
                }

            }

            friend void serialize(const input_rgb_image_sized& item, std::ostream& out)
            {
                serialize("input_rgb_image_sized", out);
                serialize(item.avg_red, out);
                serialize(item.avg_green, out);
                serialize(item.avg_blue, out);
                serialize(NR, out);
                serialize(NC, out);
            }

            friend void deserialize(input_rgb_image_sized& item, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input_rgb_image_sized")
                    throw serialization_error("Unexpected version found while deserializing dlib::input_rgb_image_sized.");
                deserialize(item.avg_red, in);
                deserialize(item.avg_green, in);
                deserialize(item.avg_blue, in);
                size_t nr, nc;
                deserialize(nr, in);
                deserialize(nc, in);
                if (nr != NR || nc != NC)
                {
                    std::ostringstream sout;
                    sout << "Wrong image dimensions found while deserializing dlib::input_rgb_image_sized.\n";
                    sout << "Expected "<<NR<<" rows and "<<NC<< " columns, but found "<<nr<<" rows and "<<nc<<" columns.";
                    throw serialization_error(sout.str());
                }
            }

            friend std::ostream& operator<<(std::ostream& out, const input_rgb_image_sized& item)
            {
                out << "input_rgb_image_sized("<<item.avg_red<<","<<item.avg_green<<","<<item.avg_blue<<") nr="<<NR<<" nc="<<NC;
                return out;
            }

            friend void to_xml(const input_rgb_image_sized& item, std::ostream& out)
            {
                out << "<input_rgb_image_sized r='"<<item.avg_red<<"' g='"<<item.avg_green<<"' b='"<<item.avg_blue<<"' nr='"<<NR<<"' nc='"<<NC<<"'/>\n";
            }

        private:
            float avg_red;
            float avg_green;
            float avg_blue;
        };

    // ----------------------------------------------------------------------------------------

        template <size_t NR, size_t NC>
        input_rgb_image::
        input_rgb_image (
            const input_rgb_image_sized<NR,NC>& item
        ) : avg_red(item.get_avg_red()),
            avg_green(item.get_avg_green()),
            avg_blue(item.get_avg_blue())
        {}

    // ----------------------------------------------------------------------------------------

        class input_rgb_image_pair
        {
        public:
            typedef std::pair<matrix<rgb_pixel>, matrix<rgb_pixel>> input_type;

            input_rgb_image_pair (
            ) :
                avg_red(122.782),
                avg_green(117.001),
                avg_blue(104.298)
            {
            }

            input_rgb_image_pair (
                float avg_red,
                float avg_green,
                float avg_blue
            ) : avg_red(avg_red), avg_green(avg_green), avg_blue(avg_blue)
            {}

            inline input_rgb_image_pair (
                const input_rgb_image& item
            ) :
                avg_red(item.get_avg_red()),
                avg_green(item.get_avg_green()),
                avg_blue(item.get_avg_blue())
            {}

            template <size_t NR, size_t NC>
            inline input_rgb_image_pair (
                const input_rgb_image_sized<NR, NC>& item
            ) :
                avg_red(item.get_avg_red()),
                avg_green(item.get_avg_green()),
                avg_blue(item.get_avg_blue())
            {}

            float get_avg_red()   const { return avg_red; }
            float get_avg_green() const { return avg_green; }
            float get_avg_blue()  const { return avg_blue; }

            bool image_contained_point ( const tensor& data, const point& p) const { return get_rect(data).contains(p); }
            drectangle tensor_space_to_image_space ( const tensor& /*data*/, drectangle r) const { return r; }
            drectangle image_space_to_tensor_space ( const tensor& /*data*/, double /*scale*/, drectangle r ) const { return r; }

            template <typename forward_iterator>
            void to_tensor (
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                DLIB_CASSERT(std::distance(ibegin, iend) > 0);
                const auto nr = ibegin->first.nr();
                const auto nc = ibegin->first.nc();

                // make sure all the input matrices have the same dimensions
                for (auto i = ibegin; i != iend; ++i)
                {
                    DLIB_CASSERT(i->first.nr() == nr && i->first.nc()==nc &&
                                 i->second.nr() == nr && i->second.nc() == nc,
                        "\t input_rgb_image_pair::to_tensor()"
                        << "\n\t All matrices given to to_tensor() must have the same dimensions."
                        << "\n\t nr: " << nr
                        << "\n\t nc: " << nc
                        << "\n\t i->first.nr(): " << i->first.nr()
                        << "\n\t i->first.nc(): " << i->first.nc()
                        << "\n\t i->second.nr(): " << i->second.nr()
                        << "\n\t i->second.nc(): " << i->second.nc()
                    );
                }

                // initialize data to the right size to contain the stuff in the iterator range.
                data.set_size(2 * std::distance(ibegin, iend), 3, nr, nc);

                const size_t offset = nr * nc;
                const size_t offset2 = data.size() / 2;
                auto ptr = data.host();
                for (auto i = ibegin; i != iend; ++i)
                {
                    for (long r = 0; r < nr; ++r)
                    {
                        for (long c = 0; c < nc; ++c)
                        {
                            rgb_pixel temp_first = i->first(r, c);
                            rgb_pixel temp_second = i->second(r, c);
                            auto p = ptr++;
                            *p = (temp_first.red - avg_red) / 256.0;
                            *(p + offset2) = (temp_second.red - avg_red) / 256.0;
                            p += offset;
                            *p = (temp_first.green - avg_green) / 256.0;
                            *(p + offset2) = (temp_second.green - avg_green) / 256.0;
                            p += offset;
                            *p = (temp_first.blue - avg_blue) / 256.0;
                            *(p + offset2) = (temp_second.blue - avg_blue) / 256.0;
                            p += offset;
                        }
                    }
                    ptr += offset * (data.k() - 1);
                }
            }

            friend void serialize(const input_rgb_image_pair& item, std::ostream& out)
            {
                serialize("input_rgb_image_pair", out);
                serialize(item.avg_red, out);
                serialize(item.avg_green, out);
                serialize(item.avg_blue, out);
            }

            friend void deserialize(input_rgb_image_pair& item, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input_rgb_image_pair" && version != "input_rgb_image" && version != "input_rgb_image_sized")
                    throw serialization_error("Unexpected version found while deserializing dlib::input_rgb_image_pair.");

                deserialize(item.avg_red, in);
                deserialize(item.avg_green, in);
                deserialize(item.avg_blue, in);
                // read and discard the sizes if this was really a sized input layer.
                if (version == "input_rgb_image_sized")
                {
                    size_t nr, nc;
                    deserialize(nr, in);
                    deserialize(nc, in);
                }
            }

            friend std::ostream& operator<<(std::ostream& out, const input_rgb_image_pair& item)
            {
                out << "input_rgb_image_pair("<< item.avg_red<<","<<item.avg_green<<","<<item.avg_blue << ")";
                return out;
            }

            friend void to_xml(const input_rgb_image_pair& item, std::ostream& out)
            {
                out << "<input_rgb_image_pair r='"<<item.avg_red<<"' g='"<<item.avg_green<<"' b='"<<item.avg_blue<<"'/>\n";
            }

        private:
            float avg_red;
            float avg_green;
            float avg_blue;
        };

    // ----------------------------------------------------------------------------------------

        input_rgb_image::
        input_rgb_image (
            const input_rgb_image_pair& item
        ) : avg_red(item.get_avg_red()),
            avg_green(item.get_avg_green()),
            avg_blue(item.get_avg_blue())
        {}

    // ----------------------------------------------------------------------------------------

        template <typename T, long NR, long NC, typename MM, typename L>
        class input<matrix<T,NR,NC,MM,L>>
        {
        public:
            typedef matrix<T,NR,NC,MM,L> input_type;

            input() {}

            template <typename mm>
            input(const input<array2d<T,mm>>&) {}

            bool image_contained_point ( const tensor& data, const point& p) const { return get_rect(data).contains(p); }
            drectangle tensor_space_to_image_space ( const tensor& /*data*/, drectangle r) const { return r; }
            drectangle image_space_to_tensor_space ( const tensor& /*data*/, double /*scale*/, drectangle r ) const { return r; }

            template <typename forward_iterator>
            void to_tensor (
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                DLIB_CASSERT(std::distance(ibegin,iend) > 0);
                const auto nr = ibegin->nr();
                const auto nc = ibegin->nc();
                // make sure all the input matrices have the same dimensions
                for (auto i = ibegin; i != iend; ++i)
                {
                    DLIB_CASSERT(i->nr()==nr && i->nc()==nc,
                        "\t input::to_tensor()"
                        << "\n\t All matrices given to to_tensor() must have the same dimensions."
                        << "\n\t nr: " << nr
                        << "\n\t nc: " << nc
                        << "\n\t i->nr(): " << i->nr()
                        << "\n\t i->nc(): " << i->nc()
                    );
                }

                // initialize data to the right size to contain the stuff in the iterator range.
                data.set_size(std::distance(ibegin,iend), pixel_traits<T>::num, nr, nc);

                typedef typename pixel_traits<T>::basic_pixel_type bptype;

                const size_t offset = nr*nc;
                auto ptr = data.host();
                for (auto i = ibegin; i != iend; ++i)
                {
                    for (long r = 0; r < nr; ++r)
                    {
                        for (long c = 0; c < nc; ++c)
                        {
                            auto temp = pixel_to_vector<float>((*i)(r,c));
                            auto p = ptr++;
                            for (long j = 0; j < temp.size(); ++j)
                            {
                                if (is_same_type<bptype,unsigned char>::value)
                                    *p = temp(j)/256.0;
                                else
                                    *p = temp(j);
                                p += offset;
                            }
                        }
                    }
                    ptr += offset*(data.k()-1);
                }

            }

            friend void serialize(const input& /*item*/, std::ostream& out)
            {
                serialize("input<matrix>", out);
            }

            friend void deserialize(input& /*item*/, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input<matrix>")
                    throw serialization_error("Unexpected version found while deserializing dlib::input.");
            }

            friend std::ostream& operator<<(std::ostream& out, const input& /*item*/)
            {
                out << "input<matrix>";
                return out;
            }

            friend void to_xml(const input& /*item*/, std::ostream& out)
            {
                out << "<input/>\n";
            }
        };

    // ----------------------------------------------------------------------------------------

        template <typename T, long NR, long NC, typename MM, typename L, size_t K>
        class input<std::array<matrix<T,NR,NC,MM,L>,K>>
        {
        public:
            typedef std::array<matrix<T,NR,NC,MM,L>,K> input_type;

            input() {}
            input(const input&) {}

            bool image_contained_point ( const tensor& data, const point& p) const { return get_rect(data).contains(p); }
            drectangle tensor_space_to_image_space ( const tensor& /*data*/, drectangle r) const { return r; }
            drectangle image_space_to_tensor_space ( const tensor& /*data*/, double /*scale*/, drectangle r ) const { return r; }

            template <typename forward_iterator>
            void to_tensor (
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                DLIB_CASSERT(std::distance(ibegin,iend) > 0);
                DLIB_CASSERT(ibegin->size() != 0, "When using std::array<matrix> inputs you can't give 0 sized arrays.");
                const auto nr = (*ibegin)[0].nr();
                const auto nc = (*ibegin)[0].nc();
                // make sure all the input matrices have the same dimensions
                for (auto i = ibegin; i != iend; ++i)
                {
                    for (size_t k = 0; k < K; ++k)
                    {
                        const auto& arr = *i;
                        DLIB_CASSERT(arr[k].nr()==nr && arr[k].nc()==nc,
                            "\t input::to_tensor()"
                            << "\n\t When using std::array<matrix> as input, all matrices in a batch must have the same dimensions."
                            << "\n\t nr: " << nr
                            << "\n\t nc: " << nc
                            << "\n\t k:  " << k
                            << "\n\t arr[k].nr(): " << arr[k].nr()
                            << "\n\t arr[k].nc(): " << arr[k].nc()
                        );
                    }
                }

                // initialize data to the right size to contain the stuff in the iterator range.
                data.set_size(std::distance(ibegin,iend), K, nr, nc);

                auto ptr = data.host();
                for (auto i = ibegin; i != iend; ++i)
                {
                    for (size_t k = 0; k < K; ++k)
                    {
                        for (long r = 0; r < nr; ++r)
                        {
                            for (long c = 0; c < nc; ++c)
                            {
                                if (is_same_type<T,unsigned char>::value)
                                    *ptr++ = (*i)[k](r,c)/256.0;
                                else
                                    *ptr++ = (*i)[k](r,c);
                            }
                        }
                    }
                }

            }

            friend void serialize(const input& /*item*/, std::ostream& out)
            {
                serialize("input<array<matrix>>", out);
            }

            friend void deserialize(input& /*item*/, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input<array<matrix>>")
                    throw serialization_error("Unexpected version found while deserializing dlib::input<array<matrix>>.");
            }

            friend std::ostream& operator<<(std::ostream& out, const input& /*item*/)
            {
                out << "input<array<matrix>>";
                return out;
            }

            friend void to_xml(const input& /*item*/, std::ostream& out)
            {
                out << "<input/>\n";
            }
        };

    // ----------------------------------------------------------------------------------------

        template <typename T, typename MM>
        class input<array2d<T,MM>>
        {
        public:
            typedef array2d<T,MM> input_type;

            input() {}
            input(const input&) {}

            template <long NR, long NC, typename mm, typename L>
            input(const input<matrix<T,NR,NC,mm,L>>&) {}

            bool image_contained_point ( const tensor& data, const point& p) const { return get_rect(data).contains(p); }
            drectangle tensor_space_to_image_space ( const tensor& /*data*/, drectangle r) const { return r; }
            drectangle image_space_to_tensor_space ( const tensor& /*data*/, double /*scale*/, drectangle r ) const { return r; }

            template <typename forward_iterator>
            void to_tensor (
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                DLIB_CASSERT(std::distance(ibegin,iend) > 0);
                const auto nr = ibegin->nr();
                const auto nc = ibegin->nc();
                // make sure all the input matrices have the same dimensions
                for (auto i = ibegin; i != iend; ++i)
                {
                    DLIB_CASSERT(i->nr()==nr && i->nc()==nc,
                        "\t input::to_tensor()"
                        << "\n\t All array2d objects given to to_tensor() must have the same dimensions."
                        << "\n\t nr: " << nr
                        << "\n\t nc: " << nc
                        << "\n\t i->nr(): " << i->nr()
                        << "\n\t i->nc(): " << i->nc()
                    );
                }

                // initialize data to the right size to contain the stuff in the iterator range.
                data.set_size(std::distance(ibegin,iend), pixel_traits<T>::num, nr, nc);
                typedef typename pixel_traits<T>::basic_pixel_type bptype;

                const size_t offset = nr*nc;
                auto ptr = data.host();
                for (auto i = ibegin; i != iend; ++i)
                {
                    for (long r = 0; r < nr; ++r)
                    {
                        for (long c = 0; c < nc; ++c)
                        {
                            auto temp = pixel_to_vector<float>((*i)[r][c]);
                            auto p = ptr++;
                            for (long j = 0; j < temp.size(); ++j)
                            {
                                if (is_same_type<bptype,unsigned char>::value)
                                    *p = temp(j)/256.0;
                                else
                                    *p = temp(j);
                                p += offset;
                            }
                        }
                    }
                    ptr += offset*(data.k()-1);
                }

            }

            friend void serialize(const input&, std::ostream& out)
            {
                serialize("input<array2d>", out);
            }

            friend void deserialize(input&, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input<array2d>")
                    throw serialization_error("Unexpected version found while deserializing dlib::input.");
            }
            friend std::ostream& operator<<(std::ostream& out, const input&)
            {
                out << "input<array2d>";
                return out;
            }

            friend void to_xml(const input&, std::ostream& out)
            {
                out << "<input/>\n";
            }
        };

    // ----------------------------------------------------------------------------------------

        namespace detail {
            template <typename PYRAMID_TYPE>
            class input_image_pyramid
            {
            public:

                virtual ~input_image_pyramid() = 0;

                typedef PYRAMID_TYPE pyramid_type;

                unsigned long get_pyramid_padding() const { return pyramid_padding; }
                void set_pyramid_padding(unsigned long value) { pyramid_padding = value; }

                unsigned long get_pyramid_outer_padding() const { return pyramid_outer_padding; }
                void set_pyramid_outer_padding(unsigned long value) { pyramid_outer_padding = value; }

                bool image_contained_point(
                    const tensor& data,
                    const point& p
                ) const
                {
                    auto&& rects = any_cast<std::vector<rectangle>>(data.annotation());
                    DLIB_CASSERT(rects.size() > 0);
                    return rects[0].contains(p + rects[0].tl_corner());
                }

                drectangle tensor_space_to_image_space(
                    const tensor& data,
                    drectangle r
                ) const
                {
                    auto&& rects = any_cast<std::vector<rectangle>>(data.annotation());
                    return tiled_pyramid_to_image<pyramid_type>(rects, r);
                }

                drectangle image_space_to_tensor_space (
                    const tensor& data,
                    double scale,
                    drectangle r
                ) const
                {
                    DLIB_CASSERT(0 < scale && scale <= 1, "scale: " << scale);
                    auto&& rects = any_cast<std::vector<rectangle>>(data.annotation());
                    return image_to_tiled_pyramid<pyramid_type>(rects, scale, r);
                }

            protected:

                template <typename forward_iterator>
                void to_tensor_init (
                    forward_iterator ibegin,
                    forward_iterator iend,
                    resizable_tensor &data,
                    unsigned int k
                ) const
                {

                    DLIB_CASSERT(std::distance(ibegin, iend) > 0);
                    auto nr = ibegin->nr();
                    auto nc = ibegin->nc();
                    // make sure all the input matrices have the same dimensions
                    for (auto i = ibegin; i != iend; ++i)
                    {
                        DLIB_CASSERT(i->nr() == nr && i->nc() == nc,
                                     "\t input_grayscale_image_pyramid::to_tensor()"
                                             << "\n\t All matrices given to to_tensor() must have the same dimensions."
                                             << "\n\t nr: " << nr
                                             << "\n\t nc: " << nc
                                             << "\n\t i->nr(): " << i->nr()
                                             << "\n\t i->nc(): " << i->nc()
                        );
                    }

                    long NR, NC;
                    pyramid_type pyr;
                    auto& rects = data.annotation().get<std::vector<rectangle>>();
                    impl::compute_tiled_image_pyramid_details(pyr, nr, nc, pyramid_padding, pyramid_outer_padding, rects,
                                                              NR, NC);

                    // initialize data to the right size to contain the stuff in the iterator range.
                    data.set_size(std::distance(ibegin, iend), k, NR, NC);

                    // We need to zero the image before doing the pyramid, since the pyramid
                    // creation code doesn't write to all parts of the image.  We also take
                    // care to avoid triggering any device to hosts copies.
                    auto ptr = data.host_write_only();
                    for (size_t i = 0; i < data.size(); ++i)
                        ptr[i] = 0;

                }

                // now build the image pyramid into data.  This does the same thing as
                // standard create_tiled_pyramid(), except we use the GPU if one is available.
                void create_tiled_pyramid (
                    const std::vector<rectangle>& rects,
                    resizable_tensor& data
                ) const
                {
                    for (size_t i = 1; i < rects.size(); ++i) {
                        alias_tensor src(data.num_samples(), data.k(), rects[i - 1].height(), rects[i - 1].width());
                        alias_tensor dest(data.num_samples(), data.k(), rects[i].height(), rects[i].width());

                        auto asrc = src(data, data.nc() * rects[i - 1].top() + rects[i - 1].left());
                        auto adest = dest(data, data.nc() * rects[i].top() + rects[i].left());

                        tt::resize_bilinear(adest, data.nc(), data.nr() * data.nc(),
                                            asrc, data.nc(), data.nr() * data.nc());
                    }
                }

                unsigned long pyramid_padding = 10;
                unsigned long pyramid_outer_padding = 11;
            };

            template <typename PYRAMID_TYPE>
            input_image_pyramid<PYRAMID_TYPE>::~input_image_pyramid() {}
        }

    // ----------------------------------------------------------------------------------------

        template <typename PYRAMID_TYPE>
        class input_grayscale_image_pyramid : public detail::input_image_pyramid<PYRAMID_TYPE>
        {
        public:
            typedef matrix<unsigned char> input_type;
            typedef PYRAMID_TYPE pyramid_type;

            template <typename forward_iterator>
            void to_tensor (
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                this->to_tensor_init(ibegin, iend, data, 1);

                const auto rects = data.annotation().get<std::vector<rectangle>>();
                if (rects.size() == 0)
                    return;

                // copy the first raw image into the top part of the tiled pyramid.  We need to
                // do this for each of the input images/samples in the tensor.
                auto ptr = data.host_write_only();
                for (auto i = ibegin; i != iend; ++i)
                {
                    auto& img = *i;
                    ptr += rects[0].top()*data.nc();
                    for (long r = 0; r < img.nr(); ++r)
                    {
                        auto p = ptr+rects[0].left();
                        for (long c = 0; c < img.nc(); ++c)
                            p[c] = (img(r,c))/256.0;
                        ptr += data.nc();
                    }
                    ptr += data.nc()*(data.nr()-rects[0].bottom()-1);
                }

                this->create_tiled_pyramid(rects, data);
            }

            friend void serialize(const input_grayscale_image_pyramid& item, std::ostream& out)
            {
                serialize("input_grayscale_image_pyramid", out);
                serialize(item.pyramid_padding, out);
                serialize(item.pyramid_outer_padding, out);
            }

            friend void deserialize(input_grayscale_image_pyramid& item, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input_grayscale_image_pyramid")
                    throw serialization_error("Unexpected version found while deserializing dlib::input_grayscale_image_pyramid.");
                deserialize(item.pyramid_padding, in);
                deserialize(item.pyramid_outer_padding, in);
            }

            friend std::ostream& operator<<(std::ostream& out, const input_grayscale_image_pyramid& item)
            {
                out << "input_grayscale_image_pyramid()";
                out << " pyramid_padding="<<item.pyramid_padding;
                out << " pyramid_outer_padding="<<item.pyramid_outer_padding;
                return out;
            }

            friend void to_xml(const input_grayscale_image_pyramid& item, std::ostream& out)
            {
                out << "<input_grayscale_image_pyramid"
                    <<"' pyramid_padding='"<<item.pyramid_padding
                    <<"' pyramid_outer_padding='"<<item.pyramid_outer_padding
                    <<"'/>\n";
            }
        };

    // ----------------------------------------------------------------------------------------

        template <typename PYRAMID_TYPE>
        class input_rgb_image_pyramid : public detail::input_image_pyramid<PYRAMID_TYPE>
        {
        public:
            typedef matrix<rgb_pixel> input_type;
            typedef PYRAMID_TYPE pyramid_type;

            input_rgb_image_pyramid (
            ) :
                avg_red(122.782),
                avg_green(117.001),
                avg_blue(104.298)
            {
            }

            input_rgb_image_pyramid (
                float avg_red_,
                float avg_green_,
                float avg_blue_
            ) : avg_red(avg_red_), avg_green(avg_green_), avg_blue(avg_blue_)
            {}

            float get_avg_red()   const { return avg_red; }
            float get_avg_green() const { return avg_green; }
            float get_avg_blue()  const { return avg_blue; }

            template <typename forward_iterator>
            void to_tensor (
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                this->to_tensor_init(ibegin, iend, data, 3);

                const auto rects = data.annotation().get<std::vector<rectangle>>();
                if (rects.size() == 0)
                    return;

                // copy the first raw image into the top part of the tiled pyramid.  We need to
                // do this for each of the input images/samples in the tensor.
                auto ptr = data.host_write_only();
                for (auto i = ibegin; i != iend; ++i)
                {
                    auto& img = *i;
                    ptr += rects[0].top()*data.nc();
                    for (long r = 0; r < img.nr(); ++r)
                    {
                        auto p = ptr+rects[0].left();
                        for (long c = 0; c < img.nc(); ++c)
                            p[c] = (img(r,c).red-avg_red)/256.0;
                        ptr += data.nc();
                    }
                    ptr += data.nc()*(data.nr()-rects[0].bottom()-1);

                    ptr += rects[0].top()*data.nc();
                    for (long r = 0; r < img.nr(); ++r)
                    {
                        auto p = ptr+rects[0].left();
                        for (long c = 0; c < img.nc(); ++c)
                            p[c] = (img(r,c).green-avg_green)/256.0;
                        ptr += data.nc();
                    }
                    ptr += data.nc()*(data.nr()-rects[0].bottom()-1);

                    ptr += rects[0].top()*data.nc();
                    for (long r = 0; r < img.nr(); ++r)
                    {
                        auto p = ptr+rects[0].left();
                        for (long c = 0; c < img.nc(); ++c)
                            p[c] = (img(r,c).blue-avg_blue)/256.0;
                        ptr += data.nc();
                    }
                    ptr += data.nc()*(data.nr()-rects[0].bottom()-1);
                }

                this->create_tiled_pyramid(rects, data);
            }

            friend void serialize(const input_rgb_image_pyramid& item, std::ostream& out)
            {
                serialize("input_rgb_image_pyramid2", out);
                serialize(item.avg_red, out);
                serialize(item.avg_green, out);
                serialize(item.avg_blue, out);
                serialize(item.pyramid_padding, out);
                serialize(item.pyramid_outer_padding, out);
            }

            friend void deserialize(input_rgb_image_pyramid& item, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input_rgb_image_pyramid" && version != "input_rgb_image_pyramid2")
                    throw serialization_error("Unexpected version found while deserializing dlib::input_rgb_image_pyramid.");
                deserialize(item.avg_red, in);
                deserialize(item.avg_green, in);
                deserialize(item.avg_blue, in);
                if (version == "input_rgb_image_pyramid2")
                {
                    deserialize(item.pyramid_padding, in);
                    deserialize(item.pyramid_outer_padding, in);
                }
                else
                {
                    item.pyramid_padding = 10;
                    item.pyramid_outer_padding = 11;
                }
            }

            friend std::ostream& operator<<(std::ostream& out, const input_rgb_image_pyramid& item)
            {
                out << "input_rgb_image_pyramid("<<item.avg_red<<","<<item.avg_green<<","<<item.avg_blue<<")";
                out << " pyramid_padding="<<item.pyramid_padding;
                out << " pyramid_outer_padding="<<item.pyramid_outer_padding;
                return out;
            }

            friend void to_xml(const input_rgb_image_pyramid& item, std::ostream& out)
            {
                out << "<input_rgb_image_pyramid r='"<<item.avg_red<<"' g='"<<item.avg_green
                    <<"' b='"<<item.avg_blue
                    <<"' pyramid_padding='"<<item.pyramid_padding
                    <<"' pyramid_outer_padding='"<<item.pyramid_outer_padding
                    <<"'/>\n";
            }

        private:
            float avg_red;
            float avg_green;
            float avg_blue;
        };

    // ----------------------------------------------------------------------------------------

        class input_tensor
        {
        public:
            typedef tensor input_type;

            input_tensor() {}
            input_tensor(const input_tensor&) {}

            template<typename forward_iterator>
            void to_tensor(
                forward_iterator ibegin,
                forward_iterator iend,
                resizable_tensor& data
            ) const
            {
                DLIB_CASSERT(std::distance(ibegin, iend) > 0);
                const auto k = ibegin->k();
                const auto nr = ibegin->nr();
                const auto nc = ibegin->nc();
                // make sure all the input tensors have the same dimensions
                for (auto i = ibegin; i != iend; ++i)
                {
                    DLIB_CASSERT(i->k() == k && i->nr() == nr && i->nc() == nc,
                        "\t input_tensor::to_tensor()"
                        << "\n\t All tensor objects given to to_tensor() must have the same dimensions."
                        << "\n\t k: " << k
                        << "\n\t nr: " << nr
                        << "\n\t nc: " << nc
                        << "\n\t i->k(): " << i->k()
                        << "\n\t i->nr(): " << i->nr()
                        << "\n\t i->nc(): " << i->nc()
                    );
                }

                const auto num_samples = count_samples(ibegin, iend);
                // initialize data to the right size to contain the stuff in the iterator range.
                data.set_size(num_samples, k, nr, nc);

                const size_t stride = k * nr * nc;
                size_t offset = 0;
                for (auto i = ibegin; i != iend; ++i)
                {
                    alias_tensor slice(i->num_samples(), k, nr, nc);
                    memcpy(slice(data, offset), *i);
                    offset += slice.num_samples() * stride;
                }
            }

            friend void serialize(const input_tensor&, std::ostream& out)
            {
                serialize("input_tensor", out);
            }

            friend void deserialize(input_tensor&, std::istream& in)
            {
                std::string version;
                deserialize(version, in);
                if (version != "input_tensor")
                    throw serialization_error("Unexpected version found while deserializing dlib::input_tensor.");
            }

            friend std::ostream& operator<<(std::ostream& out, const input_tensor&)
            {
                out << "input_tensor";
                return out;
            }

            friend void to_xml(const input_tensor&, std::ostream& out)
            {
                out << "<input_tensor/>\n";
            }

        private:

            template<typename forward_iterator>
            long long count_samples(
                forward_iterator ibegin,
                forward_iterator iend
            ) const
            {
                return std::accumulate(ibegin, iend, 0,
                    [](long long a, const auto& b) { return a + b.num_samples(); });
            }
        };

    // ----------------------------------------------------------------------------------------

    }

    #endif // DLIB_DNn_INPUT_H_