Changed default background cropping rate from 0.1 to 0.5.

dlib/image_transforms/random_cropper.h

@@ -20,7 +20,7 @@ namespace dlib
         double max_rotation_degrees = 30;
         double min_object_height = 0.25; // cropped object will be at least this fraction of the height of the image.
         double max_object_height = 0.7; // cropped object will be at most this fraction of the height of the image.
-        double background_crops_fraction = 0.1;
+        double background_crops_fraction = 0.5;
 
         std::mutex rnd_mutex;
         dlib::rand rnd;

dlib/image_transforms/random_cropper_abstract.h

@@ -37,7 +37,7 @@ namespace dlib
                 - #get_max_rotation_degrees() == 30
                 - #get_min_object_height() == 0.25
                 - #get_max_object_height() == 0.7
-                - #get_background_crops_fraction() == 0.1
+                - #get_background_crops_fraction() == 0.5
         !*/
 
         void set_seed (