HACKING: how to bisect

Closes: #181

src/img2pdf.py

@@ -1312,18 +1312,21 @@ def get_imgmetadata(
         imgwidthpx, imgheightpx = imgdata.size
 
         ndpi = imgdata.info.get("dpi")
-        if ndpi is None:
-            # the PNG plugin of PIL adds the undocumented "aspect" field instead of
-            # the "dpi" field if the PNG pHYs chunk unit is not set to meters
-            if imgformat == ImageFormat.PNG and imgdata.info.get("aspect") is not None:
-                aspect = imgdata.info["aspect"]
-                # make sure not to go below the default dpi
-                if aspect[0] > aspect[1]:
-                    ndpi = (default_dpi * aspect[0] / aspect[1], default_dpi)
-                else:
-                    ndpi = (default_dpi, default_dpi * aspect[1] / aspect[0])
+        # the PNG plugin of PIL adds the undocumented "aspect" field instead of
+        # the "dpi" field if the PNG pHYs chunk unit is not set to meters
+        if (
+            ndpi is None
+            and imgformat == ImageFormat.PNG
+            and imgdata.info.get("aspect") is not None
+        ):
+            aspect = imgdata.info["aspect"]
+            # make sure not to go below the default dpi
+            if aspect[0] > aspect[1]:
+                ndpi = (default_dpi * aspect[0] / aspect[1], default_dpi)
             else:
-                ndpi = (default_dpi, default_dpi)
+                ndpi = (default_dpi, default_dpi * aspect[1] / aspect[0])
+        else:
+            ndpi = (default_dpi, default_dpi)
         # In python3, the returned dpi value for some tiff images will
         # not be an integer but a float. To make the behaviour of
         # img2pdf the same between python2 and python3, we convert that