clarified spec

dlib/image_transforms/image_pyramid_abstract.h

@@ -199,8 +199,12 @@ namespace dlib
                 This is a function object with an interface identical to pyramid_down (defined
                 at the top of this file) except that it downsamples images at a ratio of infinity
                 to 1.  That means it always outputs images of size 0 regardless of the size
-                of the inputs.  This is useful as a method for disabling the image pyramid
-                feature of a routine which uses an image pyramid. 
+                of the inputs.  
+                
+                This is useful because it can be supplied to routines which take a pyramid_down 
+                function object and it will essentially disable pyramid processing.  This way, 
+                a pyramid oriented function can be turned into a regular routine which processes
+                just the original undownsampled image.
         !*/
     };