def dewarp(doc, method=u'dewarp'):
    """
    Removes perspective distortion (as commonly exhibited by overhead scans)
    from an 1bpp input image.

    Args:
        doc (unicode, unicode): The input document tuple.
        method (unicode): The suffix string appended to all output files.

    Returns:
        (unicode, unicode): Storage tuple of the output file
    """
    input_path = storage.get_abs_path(*doc)
    output_path = storage.insert_suffix(input_path, method)
    lept_dewarp(input_path, output_path)
    return storage.get_storage_path(output_path)