Fixed medianBlur implementation for hi-resolution images

modules/imgproc/src/median_blur.cpp

@@ -282,10 +282,10 @@ medianBlur_8u_O1( const Mat& _src, Mat& _dst, int ksize )
                         for ( ; luc[c][k] < j+r+1; ++luc[c][k] )
                         {
 #if CV_SIMD256
-                            v_fine += v256_load(px + 16 * MIN(luc[c][k], n - 1)) - v256_load(px + 16 * MAX(luc[c][k] - 2 * r - 1, 0));
+                            v_fine = v_fine + v256_load(px + 16 * MIN(luc[c][k], n - 1)) - v256_load(px + 16 * MAX(luc[c][k] - 2 * r - 1, 0));
 #elif CV_SIMD128
-                            v_finel += v_load(px + 16 * MIN(luc[c][k], n - 1)    ) - v_load(px + 16 * MAX(luc[c][k] - 2 * r - 1, 0));
-                            v_fineh += v_load(px + 16 * MIN(luc[c][k], n - 1) + 8) - v_load(px + 16 * MAX(luc[c][k] - 2 * r - 1, 0) + 8);
+                            v_finel = v_finel + v_load(px + 16 * MIN(luc[c][k], n - 1)    ) - v_load(px + 16 * MAX(luc[c][k] - 2 * r - 1, 0));
+                            v_fineh = v_fineh + v_load(px + 16 * MIN(luc[c][k], n - 1) + 8) - v_load(px + 16 * MAX(luc[c][k] - 2 * r - 1, 0) + 8);
 #else
                             for (int ind = 0; ind < 16; ++ind)
                                 H[c].fine[k][ind] += px[16 * MIN(luc[c][k], n - 1) + ind] - px[16 * MAX(luc[c][k] - 2 * r - 1, 0) + ind];
@@ -321,11 +321,11 @@ medianBlur_8u_O1( const Mat& _src, Mat& _dst, int ksize )
                     CV_Assert( b < 16 );
                 }
             }
+        }
 #if CV_SIMD
         vx_cleanup();
 #endif
     }
-    }
 
 #undef HOP
 #undef COP

modules/imgproc/test/test_filter.cpp

@@ -2200,4 +2200,15 @@ TEST(Imgproc_Filter2D, dftFilter2d_regression_10683)
 
     EXPECT_LE(cvtest::norm(dst, expected, NORM_INF), 2);
 }
+
+TEST(Imgproc_MedianBlur, hires_regression_13409)
+{
+    Mat src(2048, 2048, CV_8UC1), dst_hires, dst_ref;
+    randu(src, 0, 256);
+
+    medianBlur(src, dst_hires, 9);
+    medianBlur(src(Rect(512, 512, 1024, 1024)), dst_ref, 9);
+
+    ASSERT_EQ(0.0, cvtest::norm(dst_hires(Rect(516, 516, 1016, 1016)), dst_ref(Rect(4, 4, 1016, 1016)), NORM_INF));
+}
 }} // namespace