The documentation for GIMP Python aka PyGIMP aka Python-fu is woeful.
The official docs are here, [link].
Some web pages for beginners to start with:
- http://zwell.net/content/pygimp.html
- http://www.neuraldump.com/2017/01/program-python-plug-ins-for-gimp-hello-gimp-world/
- https://web.archive.org/web/20150808044417/http://www.exp-media.com:80/content/extending-gimp-python-python-fu-plugins-part-1
- http://tinker.kotaweaver.com/blog/?p=81
- http://muras.eu/2012/05/06/Basic-python-script-for-Gimp/
- https://patdavid.net/2014/02/getting-around-in-gimp-plug-ins-and.html
- http://gimpbook.com/scripting/ (view the slides)
- http://gimpbook.com/scripting/notes.html
- https://www.ibm.com/developerworks/library/os-autogimp/
- http://wiki.elvanor.net/index.php/GIMP_Scripting
- https://gimplearn.net/viewtopic.php/How-to-write-Plug-in-for-GIMP-in-Python?p=10844#p10844