GIMP (GNU Image Manipulation Program) is a free and open source image editing tool often used by game artists. It can be used for photo and texture editing, illustration, pixel art, and vector graphics, as well as scripted image generation & processing.
The following is the description of the GIMP software provided on the project's website as of 2018-02-25:
GIMP is a cross-platform image editor available for GNU/Linux, OS X, Windows and more operating systems. It is free software, you can change its source code and distribute your changes.
