Merge pull request #2449 from hugovk/dpi-from-exif

If DPI isn't in JPEG header, fetch from EXIF

PIL/JpegImagePlugin.py

@@ -117,6 +117,11 @@ def APP(self, marker):
         # plus constant header size
         self.info["mpoffset"] = self.fp.tell() - n + 4
 
+    # If DPI isn't in JPEG header, fetch from EXIF
+    if "dpi" not in self.info and "exif" in self.info:
+        x_resolution = self._getexif()[0x011A]
+        self.info["dpi"] = x_resolution[0] / x_resolution[1]
+
 
 def COM(self, marker):
     #

Tests/test_file_jpeg.py

@@ -167,14 +167,14 @@ class TestFileJpeg(PillowTestCase):
 
     def test_progressive_large_buffer_highest_quality(self):
         f = self.tempfile('temp.jpg')
-        im = self.gen_random_image((255,255))
+        im = self.gen_random_image((255, 255))
         # this requires more bytes than pixels in the image
         im.save(f, format="JPEG", progressive=True, quality=100)
 
     def test_progressive_cmyk_buffer(self):
         # Issue 2272, quality 90 cmyk image is tripping the large buffer bug.
         f = BytesIO()
-        im = self.gen_random_image((256,256), 'CMYK')
+        im = self.gen_random_image((256, 256), 'CMYK')
         im.save(f, format='JPEG', progressive=True, quality=94)
 
     def test_large_exif(self):
@@ -500,6 +500,14 @@ class TestFileJpeg(PillowTestCase):
         reloaded.load()
         self.assertEqual(im.info['dpi'], reloaded.info['dpi'])
 
+    def test_dpi_from_exif(self):
+        # Arrange
+        # This Photoshop CC 2017 image has DPI in EXIF not metadata
+        im = Image.open("Tests/images/photoshop-200dpi.jpg")
+
+        # Act / Assert
+        self.assertEqual(im.info.get("dpi"), 200)
+
 
 if __name__ == '__main__':
     unittest.main()