I went through the image transforms and updated their specs and a few other

things so that they still make sense now that I'm letting pixels be signed
as well as unsigned.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403972

dlib/image_transforms/edge_detector.h

@@ -97,7 +97,7 @@ namespace dlib
         out_image_type& vert
     )
     {
-        COMPILE_TIME_ASSERT(is_signed_type<typename out_image_type::type>::value);
+        COMPILE_TIME_ASSERT(pixel_traits<typename out_image_type::type>::is_unsigned == false);
         DLIB_ASSERT( (((void*)&in_img != (void*)&horz) && ((void*)&in_img != (void*)&vert) && ((void*)&vert != (void*)&horz)),
             "\tvoid sobel_edge_detector(in_img, horz, vert)"
             << "\n\tYou can't give the same image as more than one argument"
@@ -107,10 +107,10 @@ namespace dlib
             );
 
 
-        const long vert_filter[3][3] = {{-1,-2,-1}, 
+        const int vert_filter[3][3] = {{-1,-2,-1}, 
         {0,0,0}, 
         {1,2,1}};
-        const long horz_filter[3][3] = { {-1,0,1}, 
+        const int horz_filter[3][3] = { {-1,0,1}, 
         {-2,0,2}, 
         {-1,0,1}};
 
@@ -135,9 +135,11 @@ namespace dlib
         {
             for (long c = first_col; c < last_col; ++c)
             {
-                unsigned long p;
-                long horz_temp = 0;
-                long vert_temp = 0;
+                typedef typename pixel_traits<typename in_image_type::type>::basic_pixel_type bp_type;
+
+                typename promote<bp_type>::type p, horz_temp, vert_temp;
+                horz_temp = 0;
+                vert_temp = 0;
                 for (long m = 0; m < M; ++m)
                 {
                     for (long n = 0; n < N; ++n)
@@ -145,13 +147,13 @@ namespace dlib
                         // pull out the current pixel and put it into p
                         p = get_pixel_intensity(in_img[r-M/2+m][c-N/2+n]);
 
-                        horz_temp += static_cast<long>(p)*horz_filter[m][n];
-                        vert_temp += static_cast<long>(p)*vert_filter[m][n];
+                        horz_temp += p*horz_filter[m][n];
+                        vert_temp += p*vert_filter[m][n];
                     }
                 }
 
-                horz[r][c] = horz_temp;
-                vert[r][c] = vert_temp;
+                assign_pixel(horz[r][c] , horz_temp);
+                assign_pixel(vert[r][c] , vert_temp);
 
             }
         }

dlib/image_transforms/edge_detector_abstract.h

@@ -45,7 +45,7 @@ namespace dlib
             - in_image_type == is an implementation of array2d/array2d_kernel_abstract.h
             - out_image_type == is an implementation of array2d/array2d_kernel_abstract.h
             - pixel_traits<typename in_image_type::type> must be defined
-              out_image_type::type == a signed integral type
+            - pixel_traits<typename out_image_type::type>::is_unsigned == false
             - (&in_img != &horz) && (&in_img != &vert) && (&vert != &horz)
               (i.e. all three images are different image objects)
         ensures

dlib/image_transforms/equalize_histogram.h

@@ -25,6 +25,8 @@ namespace dlib
         matrix<unsigned long,R,C,MM>& hist
     )
     {
+        COMPILE_TIME_ASSERT( pixel_traits<typename in_image_type::type>::is_unsigned == true );
+
         // make sure hist is the right size
         if (R == 1)
             hist.set_size(1,pixel_traits<typename in_image_type::type>::max()+1);
@@ -59,6 +61,9 @@ namespace dlib
         COMPILE_TIME_ASSERT( pixel_traits<typename in_image_type::type>::has_alpha == false );
         COMPILE_TIME_ASSERT( pixel_traits<typename out_image_type::type>::has_alpha == false );
 
+        COMPILE_TIME_ASSERT( pixel_traits<typename in_image_type::type>::is_unsigned == true );
+        COMPILE_TIME_ASSERT( pixel_traits<typename out_image_type::type>::is_unsigned == true );
+
         typedef typename in_image_type::type in_pixel_type;
         typedef typename out_image_type::type out_pixel_type;
 

dlib/image_transforms/equalize_histogram_abstract.h

@@ -25,6 +25,8 @@ namespace dlib
             - out_image_type == is an implementation of array2d/array2d_kernel_abstract.h
             - pixel_traits<typename in_image_type::type>::has_alpha == false
             - pixel_traits<typename out_image_type::type>::has_alpha == false 
+            - pixel_traits<typename in_image_type::type>::is_unsigned == true 
+            - pixel_traits<typename out_image_type::type>::is_unsigned == true 
         ensures
             - #out_img == the histogram equalized version of in_img
             - #out_img.nc() == in_img.nc()
@@ -46,6 +48,7 @@ namespace dlib
     /*!
         requires
             - in_image_type == is an implementation of array2d/array2d_kernel_abstract.h
+            - pixel_traits<typename in_image_type::type>::is_unsigned == true 
             - hist must be capable of representing a column vector of length 
               pixel_traits<typename in_image_type>::max(). I.e. if R and C are nonzero
               then they must be values that don't conflict with the previous sentence.

dlib/image_transforms/image_pyramid.h

@@ -24,16 +24,21 @@ namespace dlib
         )
         {
             // make sure requires clause is not broken
-            DLIB_ASSERT(original.nr() > 10 && original.nc() > 10, 
+            DLIB_ASSERT(original.nr() > 10 && original.nc() > 10 &&
+                        is_same_object(original, down) == false, 
                         "\t void pyramid_down::operator()"
                         << "\n\t original.nr(): " << original.nr()
                         << "\n\t original.nc(): " << original.nc()
+                        << "\n\t is_same_object(original, down): " << is_same_object(original, down) 
                         << "\n\t this:                           " << this
                         );
 
             COMPILE_TIME_ASSERT( pixel_traits<typename in_image_type::type>::has_alpha == false );
             COMPILE_TIME_ASSERT( pixel_traits<typename out_image_type::type>::has_alpha == false );
 
+            typedef typename pixel_traits<typename in_image_type::type>::basic_pixel_type bp_type;
+            typedef typename promote<bp_type>::type ptype;
+            typename array2d<ptype>::kernel_1a temp_img;
             temp_img.set_size(original.nr(), (original.nc()-3)/2);
             down.set_size((original.nr()-3)/2, (original.nc()-3)/2);
 
@@ -50,11 +55,11 @@ namespace dlib
                 long oc = 0;
                 for (long c = 0; c < temp_img.nc(); ++c)
                 {
-                    unsigned long pix1;
-                    unsigned long pix2;
-                    unsigned long pix3;
-                    unsigned long pix4;
-                    unsigned long pix5;
+                    ptype pix1;
+                    ptype pix2;
+                    ptype pix3;
+                    ptype pix4;
+                    ptype pix5;
 
                     assign_pixel(pix1, original[r][oc]);
                     assign_pixel(pix2, original[r][oc+1]);
@@ -78,7 +83,7 @@ namespace dlib
             {
                 for (long c = 0; c < temp_img.nc(); ++c)
                 {
-                    unsigned long temp = temp_img[r-2][c] + 
+                    ptype temp = temp_img[r-2][c] + 
                                  temp_img[r-1][c]*4 +  
                                  temp_img[r  ][c]*6 +  
                                  temp_img[r-1][c]*4 +  
@@ -93,7 +98,6 @@ namespace dlib
 
     private:
 
-        array2d<unsigned long>::kernel_1a temp_img;
 
     };
 

dlib/image_transforms/image_pyramid_abstract.h

@@ -29,6 +29,7 @@ namespace dlib
             requires
                 - original.nr() > 10
                 - original.nc() > 10
+                - is_same_object(original, down) == false
                 - in_image_type == is an implementation of array2d/array2d_kernel_abstract.h
                 - out_image_type == is an implementation of array2d/array2d_kernel_abstract.h
                 - pixel_traits<typename in_image_type::type>::has_alpha == false

dlib/image_transforms/integral_image.h

@@ -35,6 +35,8 @@ namespace dlib
             const image_type& img
         )
         {
+            COMPILE_TIME_ASSERT( pixel_traits<typename image_type::type>::is_unsigned == true );
+
             unsigned long pixel;
             int_img.set_size(img.nr(), img.nc());
 

dlib/image_transforms/integral_image_abstract.h

@@ -52,7 +52,7 @@ namespace dlib
         /*!
             requires
                 - image_type == a type that implements the array2d/array2d_kernel_abstract.h interface
-                - pixel_traits<image_type::type> must be defined
+                - pixel_traits<typename image_type::type>::is_unsigned == true 
             ensures
                 - #nr() == img.nr()
                 - #nc() == img.nc()

dlib/image_transforms/spatial_filtering.h

@@ -67,15 +67,16 @@ namespace dlib
         {
             for (long c = first_col; c < last_col; ++c)
             {
-                unsigned long p;
-                long temp = 0;
+                typedef typename pixel_traits<typename in_image_type::type>::basic_pixel_type bp_type;
+                typename promote<bp_type>::type p;
+                typename promote<bp_type>::type temp = 0;
                 for (long m = 0; m < M; ++m)
                 {
                     for (long n = 0; n < N; ++n)
                     {
                         // pull out the current pixel and put it into p
                         p = get_pixel_intensity(in_img[r-M/2+m][c-N/2+n]);
-                        temp += static_cast<long>(p)*filter[m][n];
+                        temp += p*filter[m][n];
                     }
                 }
 
@@ -94,12 +95,9 @@ namespace dlib
                     }
                 }
 
-                // apply our new value for the intensity
-                p = static_cast<unsigned long>(temp);
-
                 // save this pixel to the output image
                 assign_pixel(out_img[r][c], in_img[r][c]);
-                assign_pixel_intensity(out_img[r][c],p);
+                assign_pixel_intensity(out_img[r][c], temp);
             }
         }
     }

dlib/image_transforms/thresholding.h

@@ -69,6 +69,8 @@ namespace dlib
     {
         COMPILE_TIME_ASSERT( pixel_traits<typename in_image_type::type>::has_alpha == false );
         COMPILE_TIME_ASSERT( pixel_traits<typename out_image_type::type>::has_alpha == false );
+        COMPILE_TIME_ASSERT( pixel_traits<typename in_image_type::type>::is_unsigned == true );
+        COMPILE_TIME_ASSERT( pixel_traits<typename out_image_type::type>::is_unsigned == true );
 
         COMPILE_TIME_ASSERT(pixel_traits<typename out_image_type::type>::grayscale);
 
@@ -206,7 +208,7 @@ namespace dlib
         {
             for (long c = 0; c < in_img.nc(); ++c)
             {
-                unsigned long p;
+                typename pixel_traits<typename in_image_type::type>::basic_pixel_type p;
                 assign_pixel(p,in_img[r][c]);
                 if (p >= upper_thresh)
                 {

dlib/image_transforms/thresholding_abstract.h

@@ -56,6 +56,8 @@ namespace dlib
             - pixel_traits<typename out_image_type::type>::grayscale == true  
             - pixel_traits<typename in_image_type::type>::has_alpha == false
             - pixel_traits<typename out_image_type::type>::has_alpha == false 
+            - pixel_traits<typename in_image_type::type>::is_unsigned == true 
+            - pixel_traits<typename out_image_type::type>::is_unsigned == true 
         ensures
             - #out_img == the thresholded version of in_img (in_img is converted to a grayscale
               intensity image if it is color).  Pixels in in_img with grayscale values >= thresh