Added a bunch of overloads for all the various save_*() and load_*() image

I/O options dlib supports.  Also added ones which can work directly with
a string file name.

dlib/image_loader/image_loader.h

@@ -759,6 +759,34 @@ namespace dlib
 
     }
 
+// ----------------------------------------------------------------------------------------
+
+    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_save_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_save_error("Unable to open " + file_name + " for reading.");
+        load_dng(image, fin);
+    }
+
 // ----------------------------------------------------------------------------------------
 
 }

dlib/image_loader/image_loader_abstract.h

@@ -37,7 +37,7 @@ namespace dlib
             - #image[0][0] will be the upper left corner of the image 
             - #image[image.nr()-1][image.nc()-1] will be the lower right
               corner of the image
-            - Performs any color space conversion necessairy to convert the
+            - Performs any color space conversion necessary to convert the
               BMP image data into the pixel type used by the given image
               object.
         throws
@@ -50,6 +50,25 @@ namespace dlib
                 value for its type.
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_type 
+        >
+    void load_bmp (
+        image_type& image,
+        const std::string& file_name
+    );
+    /*!
+        requires
+            - image_type == is an implementation of array2d/array2d_kernel_abstract.h
+            - pixel_traits<typename image_type::type> is defined  
+        ensures
+            - opens the file indicated by file_name with an input file stream named fin 
+              and performs:
+              load_bmp(image,fin);
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
     /*!
@@ -76,7 +95,7 @@ namespace dlib
             - #image[0][0] will be the upper left corner of the image 
             - #image[image.nr()-1][image.nc()-1] will be the lower right
               corner of the image
-            - Performs any color space conversion necessairy to convert the
+            - Performs any color space conversion necessary to convert the
               dng image data into the pixel type used by the given image
               object.
         throws
@@ -89,6 +108,25 @@ namespace dlib
                 value for its type.
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_type
+        >
+    void load_dng (
+        image_type& image,
+        const std::string& file_name
+    );
+    /*!
+        requires
+            - image_type == is an implementation of array2d/array2d_kernel_abstract.h
+            - pixel_traits<typename image_type::type> is defined  
+        ensures
+            - opens the file indicated by file_name with an input file stream named fin 
+              and performs:
+              load_dng(image,fin);
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
 }

dlib/image_loader/jpeg_loader.h

@@ -72,6 +72,22 @@ namespace dlib
         unsigned long output_components_;
         std::vector<unsigned char> data;
     };
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_type
+        >
+    void load_jpeg (
+        image_type& image,
+        const std::string& file_name
+    )
+    {
+        jpeg_loader(file_name).get_image(image);
+    }
+
+// ----------------------------------------------------------------------------------------
+
 }
 
 #ifdef NO_MAKEFILE

dlib/image_loader/jpeg_loader_abstract.h

@@ -106,6 +106,26 @@ namespace dlib
         !*/
 
     };
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_type
+        >
+    void load_jpeg (
+        image_type& image,
+        const std::string& file_name
+    );
+    /*!
+        requires
+            - image_type == is an implementation of array2d/array2d_kernel_abstract.h
+            - pixel_traits<typename image_type::type> is defined  
+        ensures
+            - performs: jpeg_loader(file_name).get_image(image);
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
 }
 
 #endif // DLIB_JPEG_IMPORT_ABSTRACT

dlib/image_loader/png_loader.h

@@ -140,6 +140,22 @@ namespace dlib
         int color_type_;
         scoped_ptr<LibpngData> ld_;
     };
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_type
+        >
+    void load_png (
+        image_type& image,
+        const std::string& file_name
+    )
+    {
+        png_loader(file_name).get_image(image);
+    }
+
+// ----------------------------------------------------------------------------------------
+
 }
 
 #ifdef NO_MAKEFILE

dlib/image_loader/png_loader_abstract.h

@@ -124,6 +124,26 @@ namespace dlib
         !*/
 
     };
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_type
+        >
+    void load_png (
+        image_type& image,
+        const std::string& file_name
+    );
+    /*!
+        requires
+            - image_type == is an implementation of array2d/array2d_kernel_abstract.h
+            - pixel_traits<typename image_type::type> is defined  
+        ensures
+            - performs: png_loader(file_name).get_image(image);
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
 }
 
 #endif // DLIB_PNG_IMPORT_ABSTRACT

dlib/image_saver/image_saver.h

@@ -5,6 +5,7 @@
 
 #include "image_saver_abstract.h"
 #include <iostream>
+#include <fstream>
 #include <sstream>
 #include "../algs.h"
 #include "../pixel.h"
@@ -13,6 +14,7 @@
 #include "../entropy_encoder_model.h"
 #include "dng_shared.h"
 #include "../uintn.h"
+#include "../dir_nav.h"
 
 namespace dlib
 {
@@ -524,6 +526,33 @@ namespace dlib
 
 // ----------------------------------------------------------------------------------------
 
+    template <typename image_type>
+    void save_dng (
+        const image_type& image,
+        const std::string& file_name
+    )
+    {
+        std::ofstream fout(file_name.c_str(), std::ios::binary);
+        if (!fout)
+            throw image_save_error("Unable to open " + file_name + " for writing.");
+        save_dng(image, fout);
+    }
+
+// ----------------------------------------------------------------------------------------
+
+    template <typename image_type>
+    void save_bmp (
+        const image_type& image,
+        const std::string& file_name
+    )
+    {
+        std::ofstream fout(file_name.c_str(), std::ios::binary);
+        if (!fout)
+            throw image_save_error("Unable to open " + file_name + " for writing.");
+        save_bmp(image, fout);
+    }
+
+// ----------------------------------------------------------------------------------------
 
 }
 

dlib/image_saver/image_saver_abstract.h

@@ -43,6 +43,25 @@ namespace dlib
             - std::bad_alloc 
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_type 
+        >
+    void save_bmp (
+        const image_type& image,
+        const std::string& file_name
+    );
+    /*!
+        requires
+            - image_type == is an implementation of array2d/array2d_kernel_abstract.h
+            - pixel_traits<typename image_type::type> is defined  
+        ensures
+            - opens the file indicated by file_name with an output file stream named fout
+              and performs:
+              save_bmp(image,fout);
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
     /*!
@@ -75,6 +94,23 @@ namespace dlib
             - std::bad_alloc 
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    template <typename image_type>
+    void save_dng (
+        const image_type& image,
+        const std::string& file_name
+    );
+    /*!
+        requires
+            - image_type == is an implementation of array2d/array2d_kernel_abstract.h
+            - pixel_traits<typename image_type::type> is defined  
+        ensures
+            - opens the file indicated by file_name with an output file stream named fout 
+              and performs:
+              save_dng(image,fout);
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
 }