added test for http://code.opencv.org/issues/2736

modules/imgproc/test/test_filter.cpp

@@ -1918,3 +1918,37 @@ TEST(Imgproc_Blur, borderTypes)
     EXPECT_EQ(expected_dst.size(), dst.size());
     EXPECT_DOUBLE_EQ(0.0, cvtest::norm(expected_dst, dst, NORM_INF));
 }
+
+TEST(Imgproc_Morphology, iterated)
+{
+    RNG& rng = theRNG();
+    for( int iter = 0; iter < 30; iter++ )
+    {
+        int width = rng.uniform(5, 33);
+        int height = rng.uniform(5, 33);
+        int cn = rng.uniform(1, 5);
+        int iterations = rng.uniform(1, 11);
+        int op = rng.uniform(0, 2);
+        Mat src(height, width, CV_8UC(cn)), dst0, dst1, dst2;
+
+        randu(src, 0, 256);
+        if( op == 0 )
+            dilate(src, dst0, Mat(), Point(-1,-1), iterations);
+        else
+            erode(src, dst0, Mat(), Point(-1,-1), iterations);
+
+        for( int i = 0; i < iterations; i++ )
+            if( op == 0 )
+                dilate(i == 0 ? src : dst1, dst1, Mat(), Point(-1,-1), 1);
+            else
+                erode(i == 0 ? src : dst1, dst1, Mat(), Point(-1,-1), 1);
+
+        Mat kern = getStructuringElement(MORPH_RECT, Size(3,3));
+        if( op == 0 )
+            dilate(src, dst2, kern, Point(-1,-1), iterations);
+        else
+            erode(src, dst2, kern, Point(-1,-1), iterations);
+        ASSERT_EQ(0.0, norm(dst0, dst1, NORM_INF));
+        ASSERT_EQ(0.0, norm(dst0, dst2, NORM_INF));
+    }
+}