Merge pull request #18053 from Yosshi999:bit-exact-resizeNN

Bit-exact Nearest Neighbor Resizing

* bit exact resizeNN

* change the value of method enum

* add bitexact-nn to ResizeExactTest

* test to compare with non-exact version

* add perf for bit-exact resizenn

* use cvFloor-equivalent

* 1/3 scaling is not stable for floating calculation

* stricter test

* bugfix: broken data in case of 6 or 12bytes elements

* bugfix: broken data in default pix_size

* stricter threshold

* use raw() for floor

* use double instead of int

* follow code reviews

* fewer cases in perf test

* center pixel convention

modules/imgproc/perf/perf_resize.cpp

@@ -254,4 +254,30 @@ PERF_TEST_P(MatInfo_Size_Scale_NN, ResizeNN,
     SANITY_CHECK_NOTHING();
 }
 
+PERF_TEST_P(MatInfo_Size_Scale_NN, ResizeNNExact,
+    testing::Combine(
+        testing::Values(CV_8UC1, CV_8UC3, CV_8UC4),
+        testing::Values(sz720p, sz1080p),
+        testing::Values(0.25, 0.5, 2.0)
+    )
+)
+{
+    int matType = get<0>(GetParam());
+    Size from = get<1>(GetParam());
+    double scale = get<2>(GetParam());
+
+    cv::Mat src(from, matType);
+
+    Size to(cvRound(from.width * scale), cvRound(from.height * scale));
+    cv::Mat dst(to, matType);
+
+    declare.in(src, WARMUP_RNG).out(dst);
+    declare.time(100);
+
+    TEST_CYCLE() resize(src, dst, dst.size(), 0, 0, INTER_NEAREST_EXACT);
+
+    EXPECT_GT(countNonZero(dst.reshape(1)), 0);
+    SANITY_CHECK_NOTHING();
+}
+
 } // namespace