code: def save_plain_image_as_file(self, filepath, format='png', quality=90):
          
          pixbuf = self.get_plain_image_as_pixbuf()
          options = {}
          if format == 'jpeg':
              options['quality'] = str(quality)
          pixbuf.save(filepath, format, options)
docs: Used for generating thumbnails.  Does not include overlaid
          graphics.