GIMP is a multi-platform photo manipulation tool. GIMP is an acronym for GNU Image Manipulation Program. The GIMP is suitable for a variety of image manipulation tasks, including photo retouching, image composition, and image construction. GIMP has many capabilities. 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, an image format converter, etc. GIMP is expandable and extensible. It is designed to be augmented with plug-ins and extensions to do just about anything. The advanced scripting interface allows everything from the simplest task to the most complex image manipulation procedures to be easily scripted. One of The GIMP's strengths is its free availability from many sources for many operating systems. Most GNU/Linux distributions include The GIMP as a standard application. The GIMP is also available for other operating systems such as Microsoft Windows or Apple's Mac OS X (Darwin). This reference manual is based on the online manual. It contains only the first half of it due to physical book size restrctions. Chapter 1 to 15 are included in this volume. Chapter 16-18 and the Appendix are included in the second volume. To keep it consistent with the online manual we did not change the index or page numbering. It is highly suggested to get both volumes (1/2 and 2/2) together.