spatialGradient: Doc, fix dangling newline error

modules/imgproc/include/opencv2/imgproc.hpp

@@ -1369,14 +1369,25 @@ CV_EXPORTS_W void Sobel( InputArray src, OutputArray dst, int ddepth,
                          double scale = 1, double delta = 0,
                          int borderType = BORDER_DEFAULT );
 
-/** @brief TODO
+/** @brief Calculates the first order image derivative in both x and y using a Sobel operator
 
-TODO
+Equivalent to calling:
 
+@code
+Sobel( src, dx, CV_16SC1, 1, 0, 3 );
+Sobel( src, dy, CV_16SC1, 0, 1, 3 );
+@endcode
+
+@param src input image.
+@param dx output image with first-order derivative in x.
+@param dy output image with first-order derivative in y.
+@param ksize size of Sobel kernel. It must be 3.
+
+@sa Sobel
  */
 
 CV_EXPORTS_W void spatialGradient( InputArray src, OutputArray dx,
-                                   OutputArray dy, int ksize );
+                                   OutputArray dy, int ksize = 3 );
 
 /** @brief Calculates the first x- or y- image derivative using Scharr operator.
 

modules/imgproc/perf/perf_spatialgradient.cpp

@@ -31,4 +31,3 @@ PERF_TEST_P( Size_Ksize, spatialGradient,
     SANITY_CHECK(dx);
     SANITY_CHECK(dy);
 }
-