spatialGradient: Remove unnecessary index calculation

modules/imgproc/src/spatialgradient.cpp

@@ -220,7 +220,6 @@ void spatialGradient( InputArray _src, OutputArray _dx, OutputArray _dy, int ksi
         for ( i = 1; i < H - 1; i++ )
         {
             // Load last row for 3x3 Sobel filter
-            idx = i*W + j;
             v_um = v_load(&p_src[idx + W - 1]);
             v_un = v_load(&p_src[idx + W]);
             v_up = v_load(&p_src[idx + W + 1]);
@@ -261,6 +260,8 @@ void spatialGradient( InputArray _src, OutputArray _dx, OutputArray _dy, int ksi
             v_snn2 = v_spn2;
             v_snp1 = v_spp1;
             v_snp2 = v_spp2;
+
+            idx += W;
         }
     }
 

modules/imgproc/test/test_filter.cpp

@@ -602,7 +602,6 @@ void CV_SpatialGradientTest::run_func()
     test_mat[OUTPUT][1] = dy;
 }
 
-
 void CV_SpatialGradientTest::prepare_to_validation( int /*test_case_idx*/ )
 {
     int dx, dy;