If you are looking for a small image editing software that is free and open source, Seashore may be the right choice for you.
The program based on GIMP for Linux is in contrast to the very extensive GIMP program greatly simplified and is aimed at all those who do not feel like learning a complete software suite and get along with the basic functions – which should be a lot.
Our general tip Acorn remains of course, but if you really only edit a picture from time to time, Seashore will be very good for you. If you want to know more about the background of the development of the app, you can read an interview with the developer here.