gimp-captcha is a program for generating difficult to break captchas, by scripting Gimp via Python.
There isn't really a way to install yet:
git clone https://github.com/isislovecruft/gimp-captcha.git cd gimp-captcha ./make-captchas --help
The script is written to generate captchas in batches, as even on a fast system it isn't usually desirable to fire up a whole gimp instance to generate a single captcha.
gimp-captcha has been tested and runs in production with gimp-2.8 on Debian-derived systems.
Portions of this code were originally created by Darrin Thompson for SpiderOak. These portions were released under the GPLv3 license and as such are released under the same license.