multiruns added to avoid the 'unreliable results' error

modules/imgproc/perf/perf_cvt_color.cpp

@@ -258,7 +258,7 @@ PERF_TEST_P(Size_CvtMode, cvtColor8u,
     declare.time(100);
     declare.in(src, WARMUP_RNG).out(dst);
 
-    int runs = sz.width <= 320 ? 70 : 1;
+    int runs = sz.width <= 320 ? 70 : 5;
     TEST_CYCLE_MULTIRUN(runs) cvtColor(src, dst, mode, ch.dcn);
 
     SANITY_CHECK(dst, 1);

modules/imgproc/perf/perf_resize.cpp

@@ -85,7 +85,8 @@ PERF_TEST_P(MatInfo_Size_Scale, ResizeAreaFast,
 
     declare.in(src, WARMUP_RNG).out(dst);
 
-    TEST_CYCLE() resize(src, dst, dst.size(), 0, 0, INTER_AREA);
+    int runs = 15;
+    TEST_CYCLE_MULTIRUN(runs) resize(src, dst, dst.size(), 0, 0, INTER_AREA);
 
     //difference equal to 1 is allowed because of different possible rounding modes: round-to-nearest vs bankers' rounding
     SANITY_CHECK(dst, 1);

modules/imgproc/perf/perf_threshold.cpp

@@ -51,7 +51,8 @@ PERF_TEST_P(Size_Only, threshold_otsu, testing::Values(TYPICAL_MAT_SIZES))
 
     declare.in(src, WARMUP_RNG).out(dst);
 
-    TEST_CYCLE() threshold(src, dst, 0, maxval, THRESH_BINARY|THRESH_OTSU);
+    int runs = 15;
+    TEST_CYCLE_MULTIRUN(runs) threshold(src, dst, 0, maxval, THRESH_BINARY|THRESH_OTSU);
 
     SANITY_CHECK(dst);
 }