I really tried to see a difference but couldn't see any blur in the portrait images...

I am not really sure what could be the reason. One thing I can do is to prevent quill from saving generated preview images

I know what's going on, gallery generate screen size preview images while I generate preview thumbnails that are half the screen size. Seems I am using libquill incorrectly somehow.

I managed to fix it in 0.0.3. It should work perfectly. The fix is not the best way but it works fine

The issue is quill is a bit under documented :P