compress_comics

Find all the cbz/cbr files in the current directory and subdirectories and compress all the jpg/png/gif images inside with jpeg xl.
Output files preserve the folder structure.
Repacks cbr into cbz.

By default, compresses with:

-d / --distance 0 (lossless)
-j / --lossless_jpeg 1

Compresses as many images in parallel as there are threads.
Because of that, it may run out of memory on bigger resolutions.
Adjust with:

-t / --threads

Basic usage:
compress_comics -O output_directory

To check all program options:
compress_comics -h

Needs cjxl installed and in PATH.