Mp3image is a project mainly written in ..., based on the BSD-3-Clause license.
Easy script to add JPEG images to the ID3 tags of MP3 files from the command line
mp3image is an easy way to write JPEG album covers to mp3 files. It's compatible with ID3v2 tags 2.2 and above (covers virtually all mp3 files). Usage is simple::
mp3image -i image_file.jpg some.mp3 mp3.mp3 files.mp3
The above example will create or overwrite the album art in all the listed .mp3 files with image_file.jpg. It doesn't do back covers or any of the other various images that an ID3v2 tag can hold (it's actually a large list) as most software won't use it when displaying.
mp3image is written in Python and uses the pytagger library, found at
http://code.google.com/p/liquidx/
mp3image was written by Jim Wyllie, with some code borrowed from Alastair Tse
for his examples on how to use pytagger. Examples cited in source.