GIMP

GIMP (GNU Image Manipulation Program) is a free and open-source raster graphics editor used for image manipulation, image editing, free-form drawing, transcoding between different image file formats, and more specialized tasks. It can be used as a simple paint program, an expert quality photo retouching program, an online batch processing system, a mass production image renderer, or an image format converter.

This software is suitable for graphic designers, photographers, illustrators, and scientists. It provides sophisticated tools to get the job done, and its customizable interface allows for a personalized workflow. GIMP is extensible through integration with many programming languages, including Scheme, Python, Perl, and Ruby.