GIMP 2.6

• Operating Systems: Windows, Mac OS X, Linux, Other Unix-like systems
• Windows download link

"GIMP" is an acronym for the "Gnu Image Manipulation Program" ("gnu" is pronounced like "new"). It is a name that is both slightly geeky and very functional, which also describes the experience of using GIMP.

Many people compare GIMP to Adobe Photoshop. Both are comprehensive image editors that provide a wide range of tools from editing digital photos to creating original artwork. Photoshop is commercial software and, in its most complete version, can cost several hundred dollars.

GIMP is free and open source. It costs nothing and, if you are a motivated programmer, you can even modify the source code itself and create your own version of GIMP.

Free software is nice, and powerful software is even better, but how easy is it to use GIMP?

Critics say that GIMP has a complicated user interface. Most image editors present a single large window inside which are a variety of tools and a canvas area containing the image being used. But, GIMP presents a collection of individual windows which, at first, seem scattered all over your desktop.

Each of these windows contains a set of useful tools. The "Toolbox" window includes icons for making selection areas, drawing, painting, filling, stamping, and so on. A separate window contains brush shapes, and yet another separate window contains a layer palette.

Note that GIMP opens every loaded image into a self-contained window, repeating the main menus in each. When you are working on several images at the same time, this can be confusing. It is too easy to accidentally shut down the entire GIMP program when you intend only to close one open image.

Applying special effects to your images is one of the coolest things you can do with GIMP. Special effects applied through "filters" can create complex visuals that would be almost impossible to achieve by hand.

GIMP includes a very large selection of filters that for most people will easily rival expensive Photoshop. Some of my favorite filters include:

• Blur: There are actually several types of blur, including plain, motion, and Gaussian. Making subtle use of these effects can soften edges of digital artwork and add a sense of movement.
• Lens Flare: Conservative use of lens flare can imitate a sense of natural light in your pictures, as if the sunshine is poking through.
• Clouds: This filter generates natural-looking clouds much easier than trying to draw them yourself!

Dozens more filters await you. Some do involve their own learning curve to create the effect you want, but the learning is part of the fun.

You don't have to worry about damaging your artwork; because GIMP includes a 5-level undo function. You can experiment with filters and undo their effects 5 levels back in history. You can even increase the undo levels to an even longer history through GIMP's main Preferences window.

You can download additional special effects for GIMP created by other users, but these are actually called "plugins."

Plug-ins are basically filters you download and install into GIMP. You can get a wide variety of plug-ins from the official GIMP Plugin Registry.

One plugin I strongly recommend is called "Save for Web". I was originally disappointed to find this feature missing from GIMP, which is included with Photoshop. You use it to preview the quality of an image when you save it using compression like JPG or PNG formats, so that you can easily find the best balance between file size and image quality.

The honest truth is that there are many more plugins available for Photoshop than GIMP. But you can install these too!

One enterprising programmer has written a GIMP plugin named PSPI, the "Photoshop Plugin." Use this to install plugins made for Photoshop, significantly expanding the choice of special effects you can choose from.