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diff --git a/ml/dlib/dlib/image_transforms/edge_detector_abstract.h b/ml/dlib/dlib/image_transforms/edge_detector_abstract.h
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+++ b/ml/dlib/dlib/image_transforms/edge_detector_abstract.h
@@ -0,0 +1,112 @@
+// Copyright (C) 2008  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#undef DLIB_EDGE_DETECTOr_ABSTRACT_
+#ifdef DLIB_EDGE_DETECTOr_ABSTRACT_
+
+#include "../pixel.h"
+#include "../image_processing/generic_image.h"
+
+namespace dlib
+{
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T
+        >
+    inline char edge_orientation (
+        const T& x,
+        const T& y
+    );
+    /*!
+        ensures
+            - returns the orientation of the line drawn from the origin to the point (x,y).
+              The orientation is represented pictorially using the four ascii 
+              characters /,|,\, and -.
+            - if (the line is horizontal) then 
+                returns '-' 
+            - if (the line is vertical) then 
+                returns '|' 
+            - if (the line is diagonal with a positive slope) then 
+                returns '/' 
+            - if (the line is diagonal with a negative slope) then 
+                returns '\\' 
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename in_image_type,
+        typename out_image_type
+        >
+    void sobel_edge_detector (
+        const in_image_type& in_img,
+        out_image_type& horz,
+        out_image_type& vert
+    );
+    /*!
+        requires
+            - in_image_type == an image object that implements the interface defined in
+              dlib/image_processing/generic_image.h 
+            - out_image_type == an image object that implements the interface defined in
+              dlib/image_processing/generic_image.h 
+            - out_image_type must use signed grayscale pixels
+            - is_same_object(in_img,horz) == false
+            - is_same_object(in_img,vert) == false
+            - is_same_object(horz,vert) == false
+        ensures
+            - Applies the sobel edge detector to the given input image and stores the resulting
+              edge detections in the horz and vert images
+            - #horz.nr() == in_img.nr()
+            - #horz.nc() == in_img.nc()
+            - #vert.nr() == in_img.nr()
+            - #vert.nc() == in_img.nc()
+            - for all valid r and c:    
+                - #horz[r][c] == the magnitude of the horizontal gradient at the point in_img[r][c]
+                - #vert[r][c] == the magnitude of the vertical gradient at the point in_img[r][c]
+                - edge_orientation(#vert[r][c], #horz[r][c]) == the edge direction at this point in 
+                  the image
+    !*/
+    
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename in_image_type,
+        typename out_image_type
+        >
+    void suppress_non_maximum_edges (
+        const in_image_type& horz,
+        const in_image_type& vert,
+        out_image_type& out_img
+    );
+    /*!
+        requires
+            - in_image_type == an image object that implements the interface defined in
+              dlib/image_processing/generic_image.h 
+            - out_image_type == an image object that implements the interface defined in
+              dlib/image_processing/generic_image.h 
+            - horz.nr() == vert.nr()
+            - horz.nc() == vert.nc()
+            - is_same_object(out_img, horz) == false
+            - is_same_object(out_img, vert) == false
+            - image_traits<in_image_type>::pixel_type == A signed scalar type (e.g. int, double, etc.) 
+        ensures
+            - #out_img.nr() = horz.nr()
+            - #out_img.nc() = horz.nc()
+            - let edge_strength(r,c) == sqrt(pow(horz[r][c],2) + pow(vert[r][c],2))
+              (i.e. The Euclidean norm of the gradient)
+            - for all valid r and c:
+                - if (edge_strength(r,c) is at a maximum with respect to its 2 neighboring
+                  pixels along the line given by edge_orientation(vert[r][c],horz[r][c])) then
+                    - performs assign_pixel(#out_img[r][c], edge_strength(r,c))
+                - else
+                    - performs assign_pixel(#out_img[r][c], 0)
+    !*/
+    
+// ----------------------------------------------------------------------------------------
+
+}
+
+#endif // DLIB_EDGE_DETECTOr_ABSTRACT_
+
+