Free Graphics Tutorials, Tomes and Tips For Mastering GIMP
GIMP, the GNU Image Manipulation Program, is a widely used and respected open source graphics program, especially attractive because it runs on Windows, the Mac and Linux. Originally created at U.C. Berkeley its interface and feature set run neck-and-neck with expensive proprietary graphics programs, and it has a huge community of developers and plug-in creators. The GIMP site has many useful resources for the application, and you can find an increasing number of ways to imbue GIMP with all the smarts of applications such as Photoshop. Here's our updated collection of great resources for GIMP, including instructions on using Photoshop filters with GIMP, a full-length free online book, and more.
Smashing Magazine has a good post about ways to tweak GIMP so it can replace Photoshop. As just one example, the PSPI plug-in from GIMP.org allows you to use the many plug-ins for Photoshop directly within GIMP. Likewise, GIMP comes with fewer brushes than Photoshop has, but you can max it out with slick brushes found at Blendfu.
Don't neglect the user manual. GIMP's user manuals are constantly updated, and available in many languages. You can download the manual here.
There are many good books on GIMP, but you may very well find everything you need in the way of instruction in Grokking the GIMP. The book is available in a free HTML tarball in addition to a printed copy that you can buy. I highly recommend looking at the links in the contents. This free, online book takes you through layers, filters, resizing tips, masks, blending colors, case studies and way more than that. Many of the step-by-step, task-based tutorials will give you what you need to perform advanced tasks.
One of the best aspects of GIMP is that it has a thriving community of plug-in developers. There are plug-ins for granular tasks such as new ways to edit images, plug-ins for more flexible graphics printing options, and more. The registry of plug-ins is here.
Keyboard shortcuts always come in handy with graphics programs, and many Photoshop users employ them. In the link at the bottom of this page, you'll find useful shortcuts for GIMP.
On GIMP's own site, you'll find many tutorials. With them, you can create floating logos, learn how to do red eye removal in photos, make vignettes out of photos, and more. There are lots more community-driven and video tutorials at Gimp-Tutorials.net. Many of the tutorials there are complemented by useful comments and tips from readers. Also, try this collection of tutorials, and this one.