dlib C++ Library - image_loader.h

    // Copyright (C) 2006  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_IMAGE_LOADEr_
    #define DLIB_IMAGE_LOADEr_

    #include "image_loader_abstract.h"
    #include <iostream>
    #include <sstream>
    #include "../algs.h"
    #include "../pixel.h"
    #include "../image_saver/dng_shared.h"
    #include "../entropy_decoder_model.h"
    #include "../entropy_decoder.h"
    #include "../uintn.h"
    #include "../image_transforms/assign_image.h"
    #include <algorithm>
    #include "../vectorstream.h"

    namespace dlib
    {

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

        class image_load_error : public dlib::error {
        public: image_load_error(const std::string& str) : error(EIMAGE_LOAD,str){}
        };

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

        template <
            typename image_type
            >
        void load_bmp (
            image_type& image_,
            std::istream& in_
        )
        {
            image_view<image_type> image(image_);
            try
            {
                unsigned long bytes_read_so_far = 0;
                unsigned long bfSize;
                unsigned long bfOffBits;
                unsigned long biSize;
                unsigned long biWidth;
                int32 biHeight;
                unsigned short biBitCount;
                unsigned long biCompression;
                unsigned long a, b, c, d, i;

                std::streambuf& in = *in_.rdbuf();
                unsigned char buf[100];

                // first make sure the BMP starts with BM
                if (in.sgetn(reinterpret_cast<char*>(buf),2) != 2)
                    throw image_load_error("bmp load error 1: header error");
                bytes_read_so_far += 2;

                if (buf[0] != 'B' || buf[1] != 'M')
                    throw image_load_error("bmp load error 2: header error");

                // now read the BITMAPFILEHEADER
                if (in.sgetn(reinterpret_cast<char*>(buf),12) != 12)
                    throw image_load_error("bmp load error 3: header error");

                bytes_read_so_far += 12;

                i = 0;
                a = buf[i]; b = buf[i+1]; c = buf[i+2]; d = buf[i+3];
                bfSize = a | (b<<8) | (c<<16) | (d<<24);

                // Ignore the next 4 bytes (Reserved Area)

                i = 8;
                a = buf[i]; b = buf[i+1]; c = buf[i+2]; d = buf[i+3];
                bfOffBits = a | (b<<8) | (c<<16) | (d<<24);

                // load the BITMAPINFOHEADER
                if (in.sgetn(reinterpret_cast<char*>(buf),40) != 40)
                    throw image_load_error("bmp load error 5: file too short");
                bytes_read_so_far += 40;

                i = 0;
                a = buf[i]; b = buf[i+1]; c = buf[i+2]; d = buf[i+3];
                biSize = a | (b<<8) | (c<<16) | (d<<24);

                i += 4;
                a = buf[i]; b = buf[i+1]; c = buf[i+2]; d = buf[i+3];
                biWidth = a | (b<<8) | (c<<16) | (d<<24);

                i += 4;
                a = buf[i]; b = buf[i+1]; c = buf[i+2]; d = buf[i+3];
                biHeight = a | (b<<8) | (c<<16) | (d<<24);

                bool bottomUp = biHeight < 0;
                if (bottomUp)
                    biHeight = 0 - biHeight;

                i += 4+2;
                a = buf[i]; b = buf[i+1];
                biBitCount = static_cast<unsigned short>(a | (b<<8));

                i += 2;
                a = buf[i]; b = buf[i+1]; c = buf[i+2]; d = buf[i+3];
                biCompression = a | (b<<8) | (c<<16) | (d<<24);

                if (biSize != 40)
                    throw image_load_error("bmp load error 6: header too small");

                image.set_size(biHeight, biWidth);

                switch (biBitCount)
                {
                    case 1:
                        {
                            // figure out how the pixels are packed
                            long padding;
                            if (bfSize - bfOffBits == biWidth*biHeight/8)
                                padding = 0;
                            else
                                padding = 4 - ((biWidth+7)/8)%4;

                            const unsigned int palette_size = 2;
                            unsigned char red[palette_size];
                            unsigned char green[palette_size];
                            unsigned char blue[palette_size];

                            for (unsigned int i = 0; i < palette_size; ++i)
                            {
                                if (in.sgetn(reinterpret_cast<char*>(buf),4) != 4)
                                {
                                    throw image_load_error("bmp load error 20: color palette missing");
                                }
                                bytes_read_so_far += 4;
                                blue[i] = buf[0];
                                green[i] = buf[1];
                                red[i] = buf[2];
                            }

                            // seek to the start of the pixel data
                            while (bytes_read_so_far != bfOffBits)
                            {
                                const long to_read = (long)std::min(bfOffBits - bytes_read_so_far, (unsigned long)sizeof(buf));
                                if (in.sgetn(reinterpret_cast<char*>(buf), to_read) != to_read)
                                {
                                    throw image_load_error("bmp load error: missing data");
                                }
                                bytes_read_so_far += to_read;
                            }

                            // load the image data
                            for (long row = biHeight-1; row >= 0; --row)
                            {
                                for (unsigned long col = 0; col < biWidth; col+=8)
                                {
                                    if (in.sgetn(reinterpret_cast<char*>(buf),1) != 1)
                                    {
                                        throw image_load_error("bmp load error 21.6: file too short");
                                    }

                                    unsigned char pixels[8];

                                    pixels[0] = (buf[0]>>7);
                                    pixels[1] = ((buf[0]>>6)&0x01);
                                    pixels[2] = ((buf[0]>>5)&0x01);
                                    pixels[3] = ((buf[0]>>4)&0x01);
                                    pixels[4] = ((buf[0]>>3)&0x01);
                                    pixels[5] = ((buf[0]>>2)&0x01);
                                    pixels[6] = ((buf[0]>>1)&0x01);
                                    pixels[7] = ((buf[0])&0x01);

                                    for (int i = 0; i < 8 && col+i < biWidth; ++i)
                                    {
                                        rgb_pixel p;
                                        p.red   = red[pixels[i]];
                                        p.green = green[pixels[i]];
                                        p.blue  = blue[pixels[i]];
                                        assign_pixel(image[bottomUp ? biHeight - row - 1 : row][col+i],p);
                                    }
                                }
                                if (in.sgetn(reinterpret_cast<char*>(buf),padding) != padding)
                                    throw image_load_error("bmp load error 9: file too short");
                            }

                        } break;
                    case 4:
                        {
                            // figure out how the pixels are packed
                            long padding;
                            if (bfSize - bfOffBits == biWidth*biHeight/2)
                                padding = 0;
                            else
                                padding = 4 - ((biWidth+1)/2)%4;

                            const unsigned int palette_size = 16;
                            unsigned char red[palette_size];
                            unsigned char green[palette_size];
                            unsigned char blue[palette_size];

                            for (unsigned int i = 0; i < palette_size; ++i)
                            {
                                if (in.sgetn(reinterpret_cast<char*>(buf),4) != 4)
                                {
                                    throw image_load_error("bmp load error 20: color palette missing");
                                }
                                bytes_read_so_far += 4;
                                blue[i] = buf[0];
                                green[i] = buf[1];
                                red[i] = buf[2];
                            }

                            // seek to the start of the pixel data
                            while (bytes_read_so_far != bfOffBits)
                            {
                                const long to_read = (long)std::min(bfOffBits - bytes_read_so_far, (unsigned long)sizeof(buf));
                                if (in.sgetn(reinterpret_cast<char*>(buf), to_read) != to_read)
                                {
                                    throw image_load_error("bmp load error: missing data");
                                }
                                bytes_read_so_far += to_read;
                            }

                            // load the image data
                            for (long row = biHeight-1; row >= 0; --row)
                            {
                                for (unsigned long col = 0; col < biWidth; col+=2)
                                {
                                    if (in.sgetn(reinterpret_cast<char*>(buf),1) != 1)
                                    {
                                        throw image_load_error("bmp load error 21.7: file too short");
                                    }

                                    const unsigned char pixel1 = (buf[0]>>4);
                                    const unsigned char pixel2 = (buf[0]&0x0F);

                                    rgb_pixel p;
                                    p.red = red[pixel1];
                                    p.green = green[pixel1];
                                    p.blue = blue[pixel1];
                                    assign_pixel(image[bottomUp ? biHeight - row - 1 : row][col], p);

                                    if (col+1 < biWidth)
                                    {
                                        p.red   = red[pixel2];
                                        p.green = green[pixel2];
                                        p.blue  = blue[pixel2];
                                        assign_pixel(image[bottomUp ? biHeight - row - 1 : row][col+1], p);
                                    }
                                }
                                if (in.sgetn(reinterpret_cast<char*>(buf),padding) != padding)
                                    throw image_load_error("bmp load error 9: file too short");
                            }

                        } break;
                    case 8:
                        {
                            // figure out how the pixels are packed
                            long padding;
                            if (bfSize - bfOffBits == biWidth*biHeight)
                                padding = 0;
                            else
                                padding = 4 - biWidth%4;

                            // check for this case.  It shouldn't happen but some BMP writers screw up the files
                            // so we have to do this.
                            if (biHeight*(biWidth+padding) > bfSize - bfOffBits)
                                padding = 0;

                            const unsigned int palette_size = 256;
                            unsigned char red[palette_size];
                            unsigned char green[palette_size];
                            unsigned char blue[palette_size];

                            for (unsigned int i = 0; i < palette_size; ++i)
                            {
                                if (in.sgetn(reinterpret_cast<char*>(buf),4) != 4)
                                {
                                    throw image_load_error("bmp load error 20: color palette missing");
                                }
                                bytes_read_so_far += 4;
                                blue[i] = buf[0];
                                green[i] = buf[1];
                                red[i] = buf[2];
                            }

                            // seek to the start of the pixel data
                            while (bytes_read_so_far != bfOffBits)
                            {
                                const long to_read = (long)std::min(bfOffBits - bytes_read_so_far, (unsigned long)sizeof(buf));
                                if (in.sgetn(reinterpret_cast<char*>(buf), to_read) != to_read)
                                {
                                    throw image_load_error("bmp load error: missing data");
                                }
                                bytes_read_so_far += to_read;
                            }

                            // Next we load the image data.

                            // if there is no RLE compression
                            if (biCompression == 0)
                            {
                                for (long row = biHeight-1; row >= 0; --row)
                                {
                                    for (unsigned long col = 0; col < biWidth; ++col)
                                    {
                                        if (in.sgetn(reinterpret_cast<char*>(buf),1) != 1)
                                        {
                                            throw image_load_error("bmp load error 21.8: file too short");
                                        }

                                        rgb_pixel p;
                                        p.red   = red[buf[0]];
                                        p.green = green[buf[0]];
                                        p.blue  = blue[buf[0]];
                                        assign_pixel(image[bottomUp ? biHeight - row - 1 : row][col],p);
                                    }
                                    if (in.sgetn(reinterpret_cast<char*>(buf),padding) != padding)
                                        throw image_load_error("bmp load error 9: file too short");
                                }
                            }
                            else
                            {
                                // Here we deal with the psychotic RLE used by BMP files.

                                // First zero the image since the RLE sometimes jumps over
                                // pixels and assumes the image has been zero initialized.
                                assign_all_pixels(image, 0);

                                long row = biHeight-1;
                                long col = 0;
                                while (true)
                                {
                                    if (in.sgetn(reinterpret_cast<char*>(buf),2) != 2)
                                    {
                                        throw image_load_error("bmp load error 21.9: file too short");
                                    }

                                    const unsigned char count = buf[0];
                                    const unsigned char command = buf[1];

                                    if (count == 0 && command == 0)
                                    {
                                        // This is an escape code that means go to the next row
                                        // of the image
                                        --row;
                                        col = 0;
                                        continue;
                                    }
                                    else if (count == 0 && command == 1)
                                    {
                                        // This is the end of the image.  So quit this loop.
                                        break;
                                    }
                                    else if (count == 0 && command == 2)
                                    {
                                        // This is the escape code for the command to jump to
                                        // a new part of the image relative to where we are now.
                                        if (in.sgetn(reinterpret_cast<char*>(buf),2) != 2)
                                        {
                                            throw image_load_error("bmp load error 21.1: file too short");
                                        }
                                        col += buf[0];
                                        row -= buf[1];
                                        continue;
                                    }
                                    else if (count == 0)
                                    {
                                        // This is the escape code for a run of uncompressed bytes

                                        if (row < 0 || col + command > image.nc())
                                        {
                                            // If this is just some padding bytes at the end then ignore them
                                            if (row >= 0 && col + count <= image.nc() + padding)
                                                continue;

                                            throw image_load_error("bmp load error 21.2: file data corrupt");
                                        }

                                        // put the bytes into the image
                                        for (unsigned int i = 0; i < command; ++i)
                                        {
                                            if (in.sgetn(reinterpret_cast<char*>(buf),1) != 1)
                                            {
                                                throw image_load_error("bmp load error 21.3: file too short");
                                            }
                                            rgb_pixel p;
                                            p.red   = red[buf[0]];
                                            p.green = green[buf[0]];
                                            p.blue  = blue[buf[0]];
                                            assign_pixel(image[bottomUp ? biHeight - row - 1 : row][col],p);

                                            ++col;
                                        }

                                        // if we read an uneven number of bytes then we need to read and
                                        // discard the next byte.
                                        if ((command&1) != 1)
                                        {
                                            if (in.sgetn(reinterpret_cast<char*>(buf),1) != 1)
                                            {
                                                throw image_load_error("bmp load error 21.4: file too short");
                                            }
                                        }

                                        continue;
                                    }

                                    rgb_pixel p;

                                    if (row < 0 || col + count > image.nc())
                                    {
                                        // If this is just some padding bytes at the end then ignore them
                                        if (row >= 0 && col + count <= image.nc() + padding)
                                            continue;

                                        throw image_load_error("bmp load error 21.5: file data corrupt");
                                    }

                                    // put the bytes into the image
                                    for (unsigned int i = 0; i < count; ++i)
                                    {
                                        p.red   = red[command];
                                        p.green = green[command];
                                        p.blue  = blue[command];
                                        assign_pixel(image[bottomUp ? biHeight - row - 1 : row][col],p);

                                        ++col;
                                    }
                                }
                            }

                        }
                        break;
                    case 16:
                        throw image_load_error ("16 bit BMP images not supported");
                    case 24:
                        {
                            // figure out how the pixels are packed
                            long padding;
                            if (bfSize - bfOffBits == biWidth*biHeight*3)
                                padding = 0;
                            else
                                padding = 4 - (biWidth*3)%4;

                            // check for this case.  It shouldn't happen but some BMP writers screw up the files
                            // so we have to do this.
                            if (biHeight*(biWidth*3+padding) > bfSize - bfOffBits)
                                padding = 0;

                            // seek to the start of the pixel data
                            while (bytes_read_so_far != bfOffBits)
                            {
                                const long to_read = (long)std::min(bfOffBits - bytes_read_so_far, (unsigned long)sizeof(buf));
                                if (in.sgetn(reinterpret_cast<char*>(buf), to_read) != to_read)
                                {
                                    throw image_load_error("bmp load error: missing data");
                                }
                                bytes_read_so_far += to_read;
                            }

                            // load the image data
                            for (long row = biHeight-1; row >= 0; --row)
                            {
                                for (unsigned long col = 0; col < biWidth; ++col)
                                {
                                    if (in.sgetn(reinterpret_cast<char*>(buf),3) != 3)
                                    {
                                        throw image_load_error("bmp load error 8: file too short");
                                    }

                                    rgb_pixel p;
                                    p.red = buf[2];
                                    p.green = buf[1];
                                    p.blue = buf[0];
                                    assign_pixel(image[bottomUp ? biHeight - row - 1 : row][col], p);

                                }
                                if (in.sgetn(reinterpret_cast<char*>(buf),padding) != padding)
                                    throw image_load_error("bmp load error 9: file too short");
                            }

                            break;
                        }
                    case 32:
                        throw image_load_error ("32 bit BMP images not supported");
                    default:
                        throw image_load_error("bmp load error 10: unknown color depth");

                }
            }
            catch (...)
            {
                image.clear();
                throw;
            }

        }

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

        template <
            typename image_type
            >
        void load_dng (
            image_type& image_,
            std::istream& in
        )
        {
            image_view<image_type> image(image_);
            using namespace dng_helpers_namespace;
            try
            {
                if (in.get() != 'D' || in.get() != 'N' || in.get() != 'G')
                    throw image_load_error("the stream does not contain a dng image file");

                unsigned long version;
                deserialize(version,in);
                if (version != 1)
                    throw image_load_error("You need the new version of the dlib library to read this dng file");

                unsigned long type;
                deserialize(type,in);

                long width, height;
                deserialize(width,in);
                deserialize(height,in);

                if (width > 0 && height > 0)
                    image.set_size(height,width);
                else
                    image.clear();

                if (type != grayscale_float)
                {
                    typedef entropy_decoder::kernel_2a decoder_type;
                    decoder_type decoder;
                    decoder.set_stream(in);

                    entropy_decoder_model<256,decoder_type>::kernel_5a edm(decoder);
                    unsigned long symbol;
                    rgb_pixel p_rgb;
                    rgb_alpha_pixel p_rgba;
                    hsi_pixel p_hsi;
                    switch (type)
                    {
                        case rgb_alpha_paeth:

                            for (long r = 0; r < image.nr(); ++r)
                            {
                                for (long c = 0; c < image.nc(); ++c)
                                {
                                    p_rgba = predictor_rgb_alpha_paeth(image,r,c);
                                    edm.decode(symbol);
                                    p_rgba.red += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgba.green += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgba.blue += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgba.alpha += static_cast<unsigned char>(symbol);

                                    assign_pixel(image[r][c],p_rgba);
                                }
                            }
                            break;

                        case rgb_alpha:

                            for (long r = 0; r < image.nr(); ++r)
                            {
                                for (long c = 0; c < image.nc(); ++c)
                                {
                                    p_rgba = predictor_rgb_alpha(image,r,c);
                                    edm.decode(symbol);
                                    p_rgba.red += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgba.green += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgba.blue += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgba.alpha += static_cast<unsigned char>(symbol);

                                    assign_pixel(image[r][c],p_rgba);
                                }
                            }
                            break;

                        case rgb_paeth:

                            for (long r = 0; r < image.nr(); ++r)
                            {
                                for (long c = 0; c < image.nc(); ++c)
                                {
                                    p_rgb = predictor_rgb_paeth(image,r,c);
                                    edm.decode(symbol);
                                    p_rgb.red += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgb.green += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgb.blue += static_cast<unsigned char>(symbol);

                                    assign_pixel(image[r][c],p_rgb);
                                }
                            }
                            break;

                        case rgb:

                            for (long r = 0; r < image.nr(); ++r)
                            {
                                for (long c = 0; c < image.nc(); ++c)
                                {
                                    p_rgb = predictor_rgb(image,r,c);
                                    edm.decode(symbol);
                                    p_rgb.red += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgb.green += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_rgb.blue += static_cast<unsigned char>(symbol);

                                    assign_pixel(image[r][c],p_rgb);
                                }
                            }
                            break;

                        case hsi:

                            for (long r = 0; r < image.nr(); ++r)
                            {
                                for (long c = 0; c < image.nc(); ++c)
                                {
                                    p_hsi = predictor_hsi(image,r,c);
                                    edm.decode(symbol);
                                    p_hsi.h += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_hsi.s += static_cast<unsigned char>(symbol);

                                    edm.decode(symbol);
                                    p_hsi.i += static_cast<unsigned char>(symbol);

                                    assign_pixel(image[r][c],p_hsi);
                                }
                            }
                            break;

                        case grayscale:
                            {
                                unsigned char p;
                                for (long r = 0; r < image.nr(); ++r)
                                {
                                    for (long c = 0; c < image.nc(); ++c)
                                    {
                                        edm.decode(symbol);
                                        p = static_cast<unsigned char>(symbol);
                                        p +=  predictor_grayscale(image,r,c);
                                        assign_pixel(image[r][c],p);
                                    }
                                }
                            }
                            break;

                        case grayscale_16bit:
                            {
                                uint16 p;
                                for (long r = 0; r < image.nr(); ++r)
                                {
                                    for (long c = 0; c < image.nc(); ++c)
                                    {
                                        edm.decode(symbol);
                                        p = static_cast<uint16>(symbol);
                                        p <<= 8;
                                        edm.decode(symbol);
                                        p |= static_cast<uint16>(symbol);

                                        p +=  predictor_grayscale_16(image,r,c);
                                        assign_pixel(image[r][c],p);
                                    }
                                }
                            }
                            break;

                        default:
                            throw image_load_error("corruption detected in the dng file");
                    } // switch (type)

                    edm.decode(symbol);
                    if (symbol != dng_magic_byte)
                        throw image_load_error("corruption detected in the dng file");
                    edm.decode(symbol);
                    if (symbol != dng_magic_byte)
                        throw image_load_error("corruption detected in the dng file");
                    edm.decode(symbol);
                    if (symbol != dng_magic_byte)
                        throw image_load_error("corruption detected in the dng file");
                    edm.decode(symbol);
                    if (symbol != dng_magic_byte)
                        throw image_load_error("corruption detected in the dng file");
                }
                else // if this is a grayscale_float type image
                {
                    std::vector<int64> man(image.size());
                    std::vector<char> expbuf;
                    // get the mantissa data
                    for (unsigned long j = 0; j < man.size(); ++j)
                        deserialize(man[j], in);
                    // get the compressed exponent data
                    deserialize(expbuf, in);
                    typedef entropy_decoder::kernel_2a decoder_type;
                    typedef entropy_decoder_model<256,decoder_type>::kernel_4a edm_exp_type;
                    vectorstream inexp(expbuf);
                    decoder_type decoder;
                    decoder.set_stream(inexp);

                    edm_exp_type edm_exp(decoder);
                    float_details prev;
                    unsigned long i = 0;
                    // fill out the image
                    for (long r = 0; r < image.nr(); ++r)
                    {
                        for (long c = 0; c < image.nc(); ++c)
                        {
                            unsigned long exp1, exp2;
                            edm_exp.decode(exp1);
                            edm_exp.decode(exp2);

                            float_details cur(man[i++],(exp2<<8) | exp1);
                            cur.exponent += prev.exponent;
                            cur.mantissa += prev.mantissa;
                            prev = cur;

                            // Only use long double precision if the target image contains long
                            // doubles because it's slower to use those.
                            if (!is_same_type<typename image_traits<image_type>::pixel_type,long double>::value)
                            {
                                double temp = cur;
                                assign_pixel(image[r][c],temp);
                            }
                            else
                            {
                                long double temp = cur;
                                assign_pixel(image[r][c],temp);
                            }
                        }
                    }
                    unsigned long symbol;
                    edm_exp.decode(symbol);
                    if (symbol != dng_magic_byte)
                        throw image_load_error("corruption detected in the dng file");
                    edm_exp.decode(symbol);
                    if (symbol != dng_magic_byte)
                        throw image_load_error("corruption detected in the dng file");
                    edm_exp.decode(symbol);
                    if (symbol != dng_magic_byte)
                        throw image_load_error("corruption detected in the dng file");
                    edm_exp.decode(symbol);
                    if (symbol != dng_magic_byte)
                        throw image_load_error("corruption detected in the dng file");
                }
            }
            catch (...)
            {
                image.clear();
                throw;
            }

        }

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

        template <typename image_type>
        void load_bmp (
            image_type& image,
            const std::string& file_name
        )
        {
            std::ifstream fin(file_name.c_str(), std::ios::binary);
            if (!fin)
                throw image_load_error("Unable to open " + file_name + " for reading.");
            load_bmp(image, fin);
        }

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

        template <typename image_type>
        void load_dng (
            image_type& image,
            const std::string& file_name
        )
        {
            std::ifstream fin(file_name.c_str(), std::ios::binary);
            if (!fin)
                throw image_load_error("Unable to open " + file_name + " for reading.");
            load_dng(image, fin);
        }

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

    }

    #endif // DLIB_IMAGE_LOADEr_