Added a mat() overload for cv_image.

dlib/opencv/cv_image.h

@@ -6,6 +6,7 @@
 #include "cv_image_abstract.h"
 #include "../algs.h"
 #include "../pixel.h"
+#include "../matrix/matrix_mat.h"
 
 namespace dlib
 {
@@ -123,6 +124,21 @@ namespace dlib
         long _nc;
     };
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T
+        >
+    const matrix_op<op_array2d_to_mat<cv_image<T> > > mat (
+        const cv_image<T>& m 
+    )
+    {
+        typedef op_array2d_to_mat<cv_image<T> > op;
+        return matrix_op<op>(op(m));
+    }
+
+// ----------------------------------------------------------------------------------------
+
 }
 
 #endif // DLIB_CvIMAGE_H_

dlib/opencv/cv_image_abstract.h

@@ -229,6 +229,24 @@ namespace dlib
         !*/
     };
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T
+        >
+    const matrix_exp mat (
+        const cv_image<T>& img
+    );
+    /*!
+        ensures
+            - returns a matrix R such that:
+                - R.nr() == img.nr() 
+                - R.nc() == img.nc()
+                - for all valid r and c:
+                  R(r, c) == img[r][c]
+    !*/
+
+// ----------------------------------------------------------------------------------------
 
 }