Image editing has become a crucial element in the photographic workflow. Image editing tools, most notably Photoshop, are usually sophisticated and deep applications, and are fairly expensive. The only open source tool in this market is the GIMP, which has developed into a powerful, multiplatform system running on Linux, Mac OS X, and Microsoft Windows. GIMP 2.6 for Photographers is a beginner's guide to the only open source image editing tool that provides a low-cost alternative to expensive programs such as Photoshop. Topics include the basics of image editing and simple adjustments, as well as advanced techniques using layers and masks, stitching panoramic images, and preparing high-quality black and white images. The most important editing functions are presented in individual, easy-to-follow workshops. GIMP 2.6 for Photographers has evolved from classroom materials that the author developed and taught in courses and workshops on image editing with the GIMP.