GIMP Ramps Up for Version 2.8 in New Test Version: Get Started With It
If you've spent any time at all working with graphics--whether you favor open source software or not--you're probably familiar with the power of GIMP, one of the very best open source graphics applications. GIMP, the GNU Image Manipulation Program, is a long-standing and hugely respected open source graphics program, and many readers probably already use it. Originally created at U.C. Berkeley its interface and feature set run neck-and-neck with expensive proprietary alternatives, and it has a thriving community of developers and plug-in creators. GIMP is now out in a development version in its 2.7.x series, and here is how to get started with it.
"There have been some significant changes to the UI...Support for layer groups have been added. They allow you to organize your image into small parts. It is now possible to tag GIMP resources such as brushes and patterns. The tagging is performed from the respective dockables e.g. the Brushes dockable, and it is possible to filter resources based on these tags."
GIMP does have a bit of a learning curve, but the good news is that there are many free resources for getting started with it. 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. The screenshots and instructions are from an older version of GIMP, but many of the tutorials will still give you what you need to perform advanced tasks. (For many more free books on open source software titles, check this post.)
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.
Of course, don't forget about GIMP documentation. There's plenty of it, and you'll find it available in many languages.