diff --git a/modules/imgproc/src/opencl/pyr_down.cl b/modules/imgproc/src/opencl/pyr_down.cl
index 4db1a8d811..b6927fa879 100644
--- a/modules/imgproc/src/opencl/pyr_down.cl
+++ b/modules/imgproc/src/opencl/pyr_down.cl
@@ -53,16 +53,16 @@
 
 #if defined BORDER_REPLICATE
 // aaaaaa|abcdefgh|hhhhhhh
-#define EXTRAPOLATE(x, maxV) clamp(x, 0, maxV-1)
+#define EXTRAPOLATE(x, maxV) clamp((x), 0, (maxV)-1)
 #elif defined BORDER_WRAP
 // cdefgh|abcdefgh|abcdefg
 #define EXTRAPOLATE(x, maxV) ( (x) + (maxV) ) % (maxV)
 #elif defined BORDER_REFLECT
 // fedcba|abcdefgh|hgfedcb
-#define EXTRAPOLATE(x, maxV) min(((maxV)-1)*2-(x)+1, max((x),-(x)-1) )
+#define EXTRAPOLATE(x, maxV) clamp(min(((maxV)-1)*2-(x)+1, max((x),-(x)-1) ), 0, (maxV)-1)
 #elif defined BORDER_REFLECT_101 || defined BORDER_REFLECT101
 // gfedcb|abcdefgh|gfedcba
-#define EXTRAPOLATE(x, maxV) min(((maxV)-1)*2-(x), max((x),-(x)) )
+#define EXTRAPOLATE(x, maxV) clamp(min(((maxV)-1)*2-(x), max((x),-(x)) ), 0, (maxV)-1)
 #else
 #error No extrapolation method
 #endif
diff --git a/modules/imgproc/test/ocl/test_pyramids.cpp b/modules/imgproc/test/ocl/test_pyramids.cpp
index beff48591e..a129c7f771 100644
--- a/modules/imgproc/test/ocl/test_pyramids.cpp
+++ b/modules/imgproc/test/ocl/test_pyramids.cpp
@@ -94,8 +94,7 @@ OCL_TEST_P(PyrDown, Mat)
 {
     for (int j = 0; j < test_loop_times; j++)
     {
-        // minimal src size is set to 4 since size<4 doesn't make sense
-        Size src_roiSize = randomSize(4, MAX_VALUE);
+        Size src_roiSize = randomSize(1, MAX_VALUE);
         Size dst_roiSize = Size(randomInt((src_roiSize.width - 1) / 2, (src_roiSize.width + 3) / 2),
                                 randomInt((src_roiSize.height - 1) / 2, (src_roiSize.height + 3) / 2));
         dst_roiSize = dst_roiSize.area() == 0 ? Size((src_roiSize.width + 1) / 2, (src_roiSize.height + 1) / 2) : dst_roiSize;