code: def save_image(self, img, filename=None, **kwargs):  # floating_point=False,
          
          filename = filename or self.get_filename(**img.data.attrs)
          nt.save(img, filename, **kwargs)
docs: Save the image to the given *filename* in ninjotiff_ format.
  
          .. _ninjotiff: http://www.ssec.wisc.edu/~davidh/polar2grid/misc/NinJo_Satellite_Import_Formats.html