code: def save_images(self, directory=None, axis='z', channel=None, global_norm=True, image_format='PNG'):
      
      if directory is None:
        directory = os.path.join('./saved_images', self.dataset_name, self.layer, str(self.mip), self.bounds.to_filename())
  
      return save_images(self, directory, axis, channel, global_norm, image_format)
docs: See cloudvolume.lib.save_images for more information.