fixing bug #3345

modules/imgproc/src/smooth.cpp

@@ -718,7 +718,7 @@ void cv::boxFilter( InputArray _src, OutputArray _dst, int ddepth,
         ddepth = sdepth;
     _dst.create( src.size(), CV_MAKETYPE(ddepth, cn) );
     Mat dst = _dst.getMat();
-    if( borderType != BORDER_CONSTANT && normalize )
+    if( borderType != BORDER_CONSTANT && normalize && (borderType & BORDER_ISOLATED) != 0 )
     {
         if( src.rows == 1 )
             ksize.height = 1;

modules/imgproc/test/test_filter.cpp

@@ -1886,3 +1886,33 @@ protected:
 };
 
 TEST(Imgproc_Filtering, supportedFormats) { CV_FilterSupportedFormatsTest test; test.safe_run(); }
+
+TEST(Imgproc_Blur, borderTypes)
+{
+    Size kernelSize(3, 3);
+
+    /// ksize > src_roi.size()
+    Mat src(3, 3, CV_8UC1, cv::Scalar::all(255)), dst;
+    Mat src_roi = src(Rect(1, 1, 1, 1));
+    src_roi.setTo(cv::Scalar::all(0));
+
+    // should work like !BORDER_ISOLATED
+    blur(src_roi, dst, kernelSize, Point(-1, -1), BORDER_REPLICATE);
+    EXPECT_EQ(227, dst.at<uchar>(0, 0));
+
+    // should work like BORDER_ISOLATED
+    blur(src_roi, dst, kernelSize, Point(-1, -1), BORDER_ISOLATED);
+    EXPECT_EQ(0, dst.at<uchar>(0, 0));
+
+    /// ksize <= src_roi.size()
+    src = Mat(5, 5, CV_8UC1, cv::Scalar(255));
+    src_roi = src(Rect(1, 1, 3, 3));
+    src_roi.setTo(0);
+    src.at<uchar>(2, 2) = 255;
+
+    // should work like !BORDER_ISOLATED
+    blur(src_roi, dst, kernelSize, Point(-1, -1), BORDER_REPLICATE);
+    Mat expected_dst =
+            (Mat_<uchar>(3, 3) << 170, 113, 170, 113, 28, 113, 170, 113, 170);
+    EXPECT_EQ(9 * 255, cv::sum(expected_dst == dst).val[0]);
+}