Photoshop was created by Thomas Knoll in 1987 and published by Adobe Systems. It is the current market leader for image manipulation software. Photoshop allows users to brighten images, enhance photos, and add special effects. Photo Pos Pro is also image editing software that is now free. It offers step-by-step help for beginners. GIMP was created by Spencer Kimball and Peter Mattis as a free image editor for Linux/Unix. It has a customizable interface and supports photo enhancement, retouching, and file formats.