Jpgtn generates smaller JPEGs from larger ones. It
can work in batches and create new files with
names based on the names of the source files. It
can dump a single thumbnail to stdout for use with
pipelines or CGI programs. Thumbnail size and
quality can be controlled by switches on the
command line. There is no maximum "thumbnail"
size, so it can be useful for creating images
suitable for web publishing from very large images
such as those taken with a good digicam.