KolourPaint is a simple painting program to quickly create raster images. It is useful as a touch-up tool and simple image editing tasks.
GThumb
gThumb is an image viewer and browser for the GNOME Desktop. It also includes an importer tool for transferring photos from cameras.
Surface
Pinta is a free, open source program for drawing and image editing.
Drawpile
Drawpile is a Free software collaborative drawing program that allows multiple users to sketch on the same canvas simultaneously.
mpitan-
This application is a basic image editor, similar to Microsoft Paint, but aiming at the GNOME desktop.
DigiKam
Professional Photo Management with the Power of Open Source
Blender
Blender is the free and open source 3D creation suite. It supports the entirety of the 3D pipeline—modeling, rigging, animation, simulation, rendering, compositing and motion tracking, video editing and 2D animation pipeline.
Shotwell
Shotwell is a personal photo manager.
Flameshot
Powerful yet simple to use screenshot software.
Photo Collage
PhotoCollage allows you to create photo collage posters.