Darktable, a raw photo post-processing applicationGIMP, a feature-rich general-purpose raster graphics editorKrita, a raster graphics editor designed primarily for digital art and 2D animation
A raster graphics editor (also called bitmap graphics editor) is a computer program that allows users to create and edit images interactively on the computer screen and save them in one of many raster graphicsfile formats (also known as bitmap images) such as JPEG, PNG, and GIF.