def _parse_ppm_segment(self, fptr):
        """Parse the PPM segment.

        Parameters
        ----------
        fptr : file
            Open file object.

        Returns
        -------
        PPMSegment
            The current PPM segment.
        """
        offset = fptr.tell() - 2

        read_buffer = fptr.read(3)
        length, zppm = struct.unpack('>HB', read_buffer)

        numbytes = length - 3
        read_buffer = fptr.read(numbytes)

        return PPMsegment(zppm, read_buffer, length, offset)