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