ce used to create the image.
            - Comment: Miscellaneous comment;
              conversion from other image format.

            Other keywords may be invented for other purposes.

            If 'Software' is not given, an autogenerated value for Matplotlib
            will be used.  This can be removed by setting it to *None*.

            For more details see the `PNG specification`_.

            .. _PNG specification:                 https://www.w3.org/TR/2003/REC-PNG-20031110/#11keywords

        pil_kwargs : dict, optional
            Keyword arguments passed to `PIL.Image.Image.save`.

            If the 'pnginfo' key is present, it completely overrides
            *metadata*, including the default 'Software' key.
        