GIMP (previously The GIMP) or GNU Image Manipulation Program is a cross-platform image editor available for GNU/Linux, macOS, Windows and more operating systems.
GIMP is free software and is the recommended way to edit textures and other images for Unvanquished.
The GIMP website is gimp.org.
The GIMP wiki is wiki.gimp.org.
The GIMP source repository is gitlab.gnome.org/GNOME/gimp.