The GNU Image Manipulation Program, or GIMP for short, is a high-quality 2D bitmap graphics creation and editing tool. The GIMP is included in most Linux distributions, and also can be downloaded from www.gimp.org. It is a part of Knoppix, the Linux distribution included on the cover of PC World magazine's October 2003 edition, and can be started by clicking the K button and selecting Multimedia-Graphics-The GIMP.
If you have ever used Adobe Photoshop, you’ll find the GIMP interface is familiar (a href="http://secure.idg.com.au/images/pcw/linuxworld_oct03.jpg"> see here for a screenshot). It’s divided into several windows, the main one containing a collection of tools and the current colours in use. Each image is displayed in its own window. Other useful windows can be brought forth by selecting them from the File-Dialogs menu in the main window.
Screenshots and scanners
If you have ever wanted to show off your Linux desktop, you can take a screenshot using the GIMP by selecting Acquire-Screen Shot from the File menu on the main GIMP window. The GIMP can take screenshots of a single window, or of your complete desktop.
If you have a scanner or TV card, you can acquire images from it using the appropriate option under the Acquire menu. After selecting an option, the XSane application will start automatically. To capture the image, all you need to do is click the Scan button in the XSane window and it will automatically be imported into the GIMP.
Extending the GIMP and Script-Fu
Modularity is at the heart of the design of the GIMP. Major aspects of the program — such as brushes, palettes and plug-ins — can all be extended via add-ons from third party sources. Finding new tools for the GIMP can greatly improve your creativity. There is no definitive resource for GIMP add-ons, so your best bet for finding them is to perform a Google search using phrases such as “gimp brushes” or “gimp palettes”.
Scripting support is one of the most powerful features built into the GIMP. All aspects of the program can be scripted using the Script-Fu language. A collection of sample scripts — many of which are so useless they can only have been included to show off what is possible — is included with the GIMP and can be accessed either by right-clicking on an image and selecting the Script-Fu menu, or by selecting Script-Fu from the Xtns menu on the main GIMP window. There are many third party Script-Fu repositories on the Web. Like extensions to the GIMP, the best way to locate extra Script-Fu scripts is via a Google search for “Script-Fu”.
Script-Fu can be a handy tool for processing large batches of images. For example, you may have a collection of holiday photos which need retouching to look their best. Using Script-Fu, you could write a script to perform a colour correction, adjust brightness and apply a sharpening filter; to retouch the image, you simply load each image and select the script from the Script-Fu menu. This is obviously a lot quicker and easier than performing each touch-up by hand.
Learning the GIMP
A number of resources are available online to teach you how to use the GIMP effectively. A good place to start is the online version of the book Grokking the GIMP, available at http://gimp-savvy.com/BOOK (you can also purchase a paper copy here). The book is now a couple of years old, but the GIMP has not changed significantly in this time so the content is still helpful and relevant.
The manual provided by www.gimp.org is also a very good resource — http://manual.gimp.org/manual/. A particular highlight of the manual is the Script-Fu tutorial located at http://manual.gimp.org/manual/GUM/write_scriptfu3.html.
After browsing the manual to get a feel for what the GIMP is capable of, you should spend some time experimenting with the features available. The GIMP is a creative tool, so ultimately there are no rules about how you should use it. Save your work as you experiment using a format such as PSD (Photoshop document) which preserves layers in images, allowing you the most flexibility when you return to edit an image later. If you are using the GIMP in Knoppix, remember to save your work to a floppy or your hard drive, as it otherwise may be lost when you exit Knoppix.