CBZXL

This Python script unpacks CBZ archives and converts .JPEG and .PNG files to JXL using lossless compression at a user configurable effort level. The script includes basic logging and error handling.

Features

• Converts JPEG and PNG to JXL losslessly
• (Optionally and Intelligently) converts images lossily
• Renames incorrect extensions using MIME type
• Corrects atypical or unusual colour spaces or metadata
• SQLite to skip reviously processed archives
• SQLite for data visualisation with companion script
• Basic logging
• Basic archive error handling
• User configurable timeout

Usage

• --effort overrides the default effort level of 10 and automatically sets the correct flags for effort 11
• --threads overrides the default of 10 threads
• --verbose for more info including per archive savings and percent saved. I recommend you pass this flag
• --quiet supresses all console messages except for critical errors
• --suppress-skipped overrides --verbose and supresses any messages indicating when an archive has been skipped
• --backup creates backups of the CBZ archives
• --dry-run
• --no-flatten prevents the script from flattening internal archive structure
• --no-convert prevent conversion to JXL but allows all other functions (including flattening)
• --stats displays database statistics
• --reprocess-failed
• --reset-db will delete both databases and allow the script to reinspect each archive from scratch
• --recheck-all will force every archive to be rescanned without requiring the database to be deleted first
• --delete-empty-archives will delete all archives which do not contain image files, even if they contain other file types
• --distance will enable lossy conversion at the specified distance e.g. 0.1
• --smart-distance triggers a lossy conversion only for images above 10MB or 5 megapixels and defaults to a distance of 0.1 or whatever distance has been specified in --distance

Visualise.py

Can be run using python visualise.py and will look for a appropriately named .db file in the working directory and use that to print some statistics inside the terminal. Additionally, --html-report MyConversionReport.html can be appended to write an HTML file containing both the statistics normally output to the console alongside embedded graphs.

Caveats

The script is pretty unsophisticated and it's up to the user to have magic, cjxl etc in their path for the script to use. As far as I can tell, it catches every edge case you're likely to encounter.