Exif parsing for PNG files to support Exif orientation tag. Moved decoder specific Exif parsing to JPEG and PNG decoders, respectively. Issue 16579

modules/imgcodecs/test/test_png.cpp

@@ -7,6 +7,12 @@ namespace opencv_test { namespace {
 
 #ifdef HAVE_PNG
 
+#ifdef HAVE_LIBPNG_PNG_H
+#include <libpng/png.h>
+#else
+#include <png.h>
+#endif
+
 TEST(Imgcodecs_Png, write_big)
 {
     const string root = cvtest::TS::ptr()->get_data_path();
@@ -93,6 +99,97 @@ TEST(Imgcodecs_Png, read_color_palette_with_alpha)
     EXPECT_EQ(img.at<Vec3b>(0, 1), Vec3b(0, 0, 255));
 }
 
+#ifdef PNG_eXIf_SUPPORTED
+/**
+ * Test for check whether reading exif orientation tag was processed successfully or not
+ * The test info is the set of 8 images named testExifRotate_{1 to 8}.png
+ * The test image is the square 10x10 points divided by four sub-squares:
+ * (R corresponds to Red, G to Green, B to Blue, W to white)
+ * ---------             ---------
+ * | R | G |             | G | R |
+ * |-------| - (tag 1)   |-------| - (tag 2)
+ * | B | W |             | W | B |
+ * ---------             ---------
+ *
+ * ---------             ---------
+ * | W | B |             | B | W |
+ * |-------| - (tag 3)   |-------| - (tag 4)
+ * | G | R |             | R | G |
+ * ---------             ---------
+ *
+ * ---------             ---------
+ * | R | B |             | G | W |
+ * |-------| - (tag 5)   |-------| - (tag 6)
+ * | G | W |             | R | B |
+ * ---------             ---------
+ *
+ * ---------             ---------
+ * | W | G |             | B | R |
+ * |-------| - (tag 7)   |-------| - (tag 8)
+ * | B | R |             | W | G |
+ * ---------             ---------
+ *
+ *
+ * Every image contains exif field with orientation tag (0x112)
+ * After reading each image and applying the orientation tag,
+ * the resulting image should be:
+ * ---------
+ * | R | G |
+ * |-------|
+ * | B | W |
+ * ---------
+ *
+ */
+
+typedef testing::TestWithParam<string> Imgcodecs_PNG_Exif;
+
+// Solution to issue 16579: PNG read doesn't support Exif orientation data
+TEST_P(Imgcodecs_PNG_Exif, exif_orientation)
+{
+    const string root = cvtest::TS::ptr()->get_data_path();
+    const string filename = root + GetParam();
+    const int colorThresholdHigh = 250;
+    const int colorThresholdLow = 5;
+
+    Mat m_img = imread(filename);
+    ASSERT_FALSE(m_img.empty());
+    Vec3b vec;
+
+    //Checking the first quadrant (with supposed red)
+    vec = m_img.at<Vec3b>(2, 2); //some point inside the square
+    EXPECT_LE(vec.val[0], colorThresholdLow);
+    EXPECT_LE(vec.val[1], colorThresholdLow);
+    EXPECT_GE(vec.val[2], colorThresholdHigh);
+
+    //Checking the second quadrant (with supposed green)
+    vec = m_img.at<Vec3b>(2, 7);  //some point inside the square
+    EXPECT_LE(vec.val[0], colorThresholdLow);
+    EXPECT_GE(vec.val[1], colorThresholdHigh);
+    EXPECT_LE(vec.val[2], colorThresholdLow);
+
+    //Checking the third quadrant (with supposed blue)
+    vec = m_img.at<Vec3b>(7, 2);  //some point inside the square
+    EXPECT_GE(vec.val[0], colorThresholdHigh);
+    EXPECT_LE(vec.val[1], colorThresholdLow);
+    EXPECT_LE(vec.val[2], colorThresholdLow);
+}
+
+const string exif_files[] =
+{
+    "readwrite/testExifOrientation_1.png",
+    "readwrite/testExifOrientation_2.png",
+    "readwrite/testExifOrientation_3.png",
+    "readwrite/testExifOrientation_4.png",
+    "readwrite/testExifOrientation_5.png",
+    "readwrite/testExifOrientation_6.png",
+    "readwrite/testExifOrientation_7.png",
+    "readwrite/testExifOrientation_8.png"
+};
+
+INSTANTIATE_TEST_CASE_P(ExifFiles, Imgcodecs_PNG_Exif,
+    testing::ValuesIn(exif_files));
+#endif // PNG_eXIf_SUPPORTED
+
 #endif // HAVE_PNG
 
 }} // namespace