Resize WEBP animations

resize.py

import argparse
import textwrap

from PIL import Image, ImageSequence


def main() -> None:
    parser = argparse.ArgumentParser(
        description=textwrap.indent(
            textwrap.dedent(
                """
                Simple tool to resize WEBP animations based on the Pillow library.

                For the resize options, check:
                https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.resize

                For the WEBP writing options, check:
                https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html#webp
                """
            ).strip(),
            '    ',
        ),
        formatter_class=argparse.RawTextHelpFormatter,
    )
    parser.add_argument('input', type=str, help='input file')
    parser.add_argument('output', type=str, help='output file')
    resize_group = parser.add_argument_group('resize', 'Options related to the image resizing')
    resize_group.add_argument('size', type=int, nargs='+')
    resize_group.add_argument('--resample', type=str, choices=Image.Resampling.__members__.keys(), required=False)
    resize_group.add_argument('--reducing-gap', type=int, required=False)
    webp_group = parser.add_argument_group('webp', 'Options related to the WEBP writing')
    webp_group.add_argument('--lossless', type=bool, required=False)
    webp_group.add_argument('--quality', type=int, required=False)
    webp_group.add_argument('--method', type=int, required=False)
    webp_group.add_argument('--exact', type=bool, required=False)

    args = parser.parse_args()

    if len(args.size) == 1:
        size = (args.size[0], args.size[0])
    elif len(args.size) == 2:
        size = tuple(args.size)
    else:
        raise ValueError(f'Invalid size argument: {args.size}')

    resize_args = {'size': size}
    if args.resample:
        resize_args['resample'] = Image.Resampling.__members__[args.resample]
    if args.reducing_gap:
        resize_args['reducing_gap'] = args.reducing_gap

    webp_args = {}
    if args.lossless:
        webp_args['lossless'] = args.lossless
    if args.quality:
        webp_args['quality'] = args.quality
    if args.method:
        webp_args['method'] = args.method
    if args.exact:
        webp_args['exact'] = args.exact

    original = Image.open(args.input)
    resized_frames = ImageSequence.all_frames(original, lambda im: im.resize(**resize_args))
    resized_frames[0].save(
        args.output,
        save_all=True,
        append_images=resized_frames[1:],
        **webp_args,
    )


if __name__ == '__main__':
    main()