画像形式WebPと他形式との変換に用いるコマンド

$ cwebp -q [品質値(0-100)] /path/to/input.jpg -o /path/to/output.webp

$ cwebp -lossless /path/to/input.png -o /path/to/output.webp

$ dwebp /path/to/input.webp -o /path/to/output.png

#! /usr/bin/python

"""
png2losslesswebp.py - convert PNG to lossless WebP.

(C) 2019-2020 kakurasan
Licensed under zlib
"""

from __future__ import print_function

import multiprocessing as mp
import os
try:
    import queue
except ImportError:
    import Queue as queue
import subprocess
import sys


# pylint: disable=too-few-public-methods
class Config:
    """Configuration data."""

    cwebp = "/usr/bin/cwebp"  # path to cwebp
    options = ["-lossless", "-quiet"]


def run_cwebp(fname, root):
    """Run cwebp and copy last modified date/time from original PNG file."""
    f_lower = fname.lower()
    if f_lower.endswith(".png"):
        infile = os.path.join(root, fname)
        outfile = os.path.join(
            root, "{}.webp".format(fname[:fname.rfind(".")]))
        print("Converting '{}'".format(infile))
        try:
            subprocess.check_call(
                [Config.cwebp] + Config.options + [infile, "-o", outfile],
            )
        except subprocess.CalledProcessError:
            print("Failed to convert '{}'".format(infile))
            return
        st_before = os.stat(infile)
        os.utime(outfile, (st_before.st_atime, st_before.st_mtime))


def worker(que):
    """Get filename and root from the queue and call run_cwebp()."""
    while True:
        try:
            fname, root = que.get(True, 1)
            run_cwebp(fname, root)
            que.task_done()
        except queue.Empty:
            break


def main():
    """Put paths into a JoinableQueue and start processes."""
    if len(sys.argv) < 2:
        sys.exit("USAGE: {} [DIR...]".format(__file__))
    que = mp.JoinableQueue()
    for topdir in sys.argv[1:]:
        for root, _, files in os.walk(topdir):
            for fname in files:
                que.put((fname, root))
    for _ in range(mp.cpu_count()):
        proc = mp.Process(target=worker, args=(que,))
        proc.start()
    que.join()


if __name__ == "__main__":
    main()

(指定ディレクトリ内のPNG画像をWebP形式に一括変換)
$ /path/to/png2losslesswebp.py /path/to/png/dir