Tweak error threshold for an image comparison involving subtitles.

3 files changed, 8 insertions, 4 deletions

diff --git a/test/player_test.cc b/test/player_test.cc
index e22570bc0..585d357df 100644
--- a/test/player_test.cc
+++ b/test/player_test.cc
@@ -227,7 +227,11 @@ BOOST_AUTO_TEST_CASE (player_seek_test)
 		pair<shared_ptr<PlayerVideo>, DCPTime> video = butler->get_video();
 		BOOST_CHECK_EQUAL(video.second.get(), t.get());
 		write_image(video.first->image(note_handler, PlayerVideo::always_rgb, false, true), String::compose("build/test/player_seek_test_%1.png", i), "RGB");
-		check_image(String::compose("test/data/player_seek_test_%1.png", i), String::compose("build/test/player_seek_test_%1.png", i));
+		/* This 0.011 is empirically chosen (hopefully) to accept changes in rendering between the reference and a test machine
+		   (17.10 and 16.04 seem to anti-alias a little differently) but to reject gross errors e.g. missing fonts or missing
+		   text altogether.
+		*/
+		check_image(String::compose("test/data/player_seek_test_%1.png", i), String::compose("build/test/player_seek_test_%1.png", i), 0.011);
 	}
 }
 
diff --git a/test/test.cc b/test/test.cc
index 9e168b1e2..68c1cfccd 100644
--- a/test/test.cc
+++ b/test/test.cc
@@ -231,7 +231,7 @@ check_mxf_audio_file (boost::filesystem::path ref, boost::filesystem::path check
 }
 
 void
-check_image (boost::filesystem::path ref, boost::filesystem::path check)
+check_image (boost::filesystem::path ref, boost::filesystem::path check, double threshold)
 {
 #ifdef DCPOMATIC_IMAGE_MAGICK
 	using namespace MagickCore;
@@ -248,7 +248,7 @@ check_image (boost::filesystem::path ref, boost::filesystem::path check)
 	*/
 #ifdef DCPOMATIC_ADVANCED_MAGICK_COMPARE
 	double const dist = ref_image.compare(check_image, Magick::RootMeanSquaredErrorMetric);
-	BOOST_CHECK_MESSAGE (dist < 0.01, ref << " differs from " << check << " " << dist);
+	BOOST_CHECK_MESSAGE (dist < threshold, ref << " differs from " << check << " " << dist);
 #else
 	BOOST_CHECK_MESSAGE (!ref_image.compare(check_image), ref << " differs from " << check);
 #endif
diff --git a/test/test.h b/test/test.h
index 78fa26b43..5e030f0cc 100644
--- a/test/test.h
+++ b/test/test.h
@@ -36,7 +36,7 @@ extern void check_mxf_audio_file (boost::filesystem::path ref, boost::filesystem
 extern void check_xml (boost::filesystem::path, boost::filesystem::path, std::list<std::string>);
 extern void check_file (boost::filesystem::path, boost::filesystem::path);
 extern void check_ffmpeg (boost::filesystem::path, boost::filesystem::path, int audio_tolerance);
-extern void check_image (boost::filesystem::path, boost::filesystem::path);
+extern void check_image (boost::filesystem::path, boost::filesystem::path, double threshold = 0.01);
 extern boost::filesystem::path test_film_dir (std::string);
 extern void write_image (boost::shared_ptr<const Image> image, boost::filesystem::path file, std::string format);
 boost::filesystem::path dcp_file (boost::shared_ptr<const Film> film, std::string prefix);