Revert optimization for warpAffine INTER_NEAREST mode

modules/imgproc/src/opencl/warp_affine.cl

@@ -98,15 +98,15 @@ __kernel void warpAffine(__global const uchar * srcptr, int src_step, int src_of
     {
         int round_delta = (AB_SCALE >> 1);
 
-        int X0 = rint(fma(M[0], dx, fma(M[1], dy0, M[2])) * AB_SCALE) + round_delta;
-        int Y0 = rint(fma(M[3], dx, fma(M[4], dy0, M[5])) * AB_SCALE) + round_delta;
-
-        int XSTEP = (int)(M[1] * AB_SCALE);
-        int YSTEP = (int)(M[4] * AB_SCALE);
+        int X0_ = rint(M[0] * dx * AB_SCALE);
+        int Y0_ = rint(M[3] * dx * AB_SCALE);
         int dst_index = mad24(dy0, dst_step, mad24(dx, pixsize, dst_offset));
 
         for (int dy = dy0, dy1 = min(dst_rows, dy0 + rowsPerWI); dy < dy1; ++dy, dst_index += dst_step)
         {
+            int X0 = X0_ + rint(fma(M[1], dy, M[2]) * AB_SCALE) + round_delta;
+            int Y0 = Y0_ + rint(fma(M[4], dy, M[5]) * AB_SCALE) + round_delta;
+
             short sx = convert_short_sat(X0 >> AB_BITS);
             short sy = convert_short_sat(Y0 >> AB_BITS);
 
@@ -117,9 +117,6 @@ __kernel void warpAffine(__global const uchar * srcptr, int src_step, int src_of
             }
             else
                 storepix(scalar, dstptr + dst_index);
-
-            X0 += XSTEP;
-            Y0 += YSTEP;
         }
     }
 }
@@ -376,4 +373,4 @@ __kernel void warpAffine(__global const uchar * srcptr, int src_step, int src_of
     }
 }
 
-#endif
+#endif

modules/imgproc/src/pyramids.cpp

@@ -413,6 +413,9 @@ static bool ocl_pyrDown( InputArray _src, OutputArray _dst, const Size& _dsz, in
 
     Size ssize = _src.size();
     Size dsize = _dsz.area() == 0 ? Size((ssize.width + 1) / 2, (ssize.height + 1) / 2) : _dsz;
+    if (dsize.height < 2 || dsize.width < 2)
+        return false;
+
     CV_Assert( ssize.width > 0 && ssize.height > 0 &&
             std::abs(dsize.width*2 - ssize.width) <= 2 &&
             std::abs(dsize.height*2 - ssize.height) <= 2 );

modules/imgproc/test/ocl/test_pyramids.cpp

@@ -94,7 +94,8 @@ OCL_TEST_P(PyrDown, Mat)
 {
     for (int j = 0; j < test_loop_times; j++)
     {
-        Size src_roiSize = randomSize(1, MAX_VALUE);
+        // minimal src size is set to 4 since size<4 doesn't make sense
+        Size src_roiSize = randomSize(4, 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;