another fix for #2332 test

modules/highgui/test/test_grfmt.cpp

@@ -254,17 +254,15 @@ public:
 };
 
 TEST(Highgui_Image, encode_png) { CV_GrfmtPNGEncodeTest test; test.safe_run(); }
-#endif
 
-#ifdef HAVE_JPEG
 TEST(Highgui_ImreadVSCvtColor, regression)
 {
     cvtest::TS& ts = *cvtest::TS::ptr();
 
-    const int MAX_MEAN_DIFF = 3;
+    const int MAX_MEAN_DIFF = 1;
     const int MAX_ABS_DIFF = 10;
 
-    string imgName = string(ts.get_data_path()) + "/../cv/shared/lena.jpg";
+    string imgName = string(ts.get_data_path()) + "/../cv/shared/lena.png";
     Mat original_image = imread(imgName);
     Mat gray_by_codec = imread(imgName, 0);
     Mat gray_by_cvt;
@@ -277,6 +275,7 @@ TEST(Highgui_ImreadVSCvtColor, regression)
     double actual_avg_diff = (double)mean(diff)[0];
     double actual_maxval, actual_minval;
     minMaxLoc(diff, &actual_minval, &actual_maxval);
+	//printf("actual avg = %g, actual maxdiff = %g, npixels = %d\n", actual_avg_diff, actual_maxval, (int)diff.total());
 
     EXPECT_LT(actual_avg_diff, MAX_MEAN_DIFF);
     EXPECT_LT(actual_maxval, MAX_ABS_DIFF);