Editing Images with The GIMP


Time was when the GNU Image Manipulation Program (GIMP) was touted as the "killer app" that would drive ordinary desktop users to Linux. A professional image editor whose features rivaled the fabled Adobe Photoshop on Windows that didn't cost several hundred dollars (well, one that didn't cost anything) is just what people need, some analysts thought. It didn't happen exactly that way, but it remains reasonable to say that Linux for the masses wouldn't be here if not for The GIMP.

Tip

To learn more about the role of The GIMP and the toolkit that spawned dozens of GUI products, see the section on GNOME in Chapter 6.


Photographers, animators, web designers, and other artists use The GIMP in all sorts of ways. The nonhuman characters in the Scooby Doo movies were created with the help of a GIMP spinoff now called CinePaint.

So what can you do with The GIMP? Just about any photo or other graphic-editing task. The GIMP can import and export more than 30 image formats, including Photoshop's native format. It supports layers (letting you easily add and remove text or other effects from an image) and has all the tools people expect from a modern image editor.

Version 2.2 of The GIMP, released in December 2004, features a more usable interface, better drag-and-drop support, and a shortcut editor.

To run The GIMP from the shell, type gimp &. The ampersand (&) launches The GIMP in the background and returns you to the shell prompt.

Otherwise, The GIMP can be found in the Graphics menu in the KDE or GNOME start menus. The first time you run The GIMP, you'll be asked a few startup configuration questions, but then you're on your way.

When you open The GIMP without an image, you'll see the toolbox first; these icons offer the basic utensils for editing an image. Depending on the version installed on your system, more than 30 tool icons could be available to you in the toolbox.

To create a new image, press Ctrl+N (or go to File, New). To open an existing image for editing, press Ctrl+O and an image window appears. Both the toolbox and the image window have their own menus. Open the File menu in either window to open and save graphics and perform other file-management tasks. The Toolbox Extensions menu (Xtns) contains the plug-ins and other enhanced functionality that make The GIMP special.

Right-clicking anywhere in an image window also gives you access to a context menu with a wealth of choices to work with your image (see Figure 10.4).

Figure 10.4. Just a hint of the choices you have available when right-clicking in a GIMP image.


In the right edge of the menu are two important options, Python-fu and Script-fu. Both offer ways to automate tasks and do all sorts of cool things. Script-fu is the original GIMP scripting language, but because it's based on a relatively obscure programming language, Scheme, it's hard to learn. GIMP 2.0 introduced Python-fu, based on the famous (and famously easy to use and learn) Python scripting language.

The GIMP's Help files are quite good. It doesn't hurt for newbies (either to The GIMP or to image editing in general) to read the manual.

Photoshop Versus The GIMP

Two large obstacles prevent The GIMP from becoming a standard prepress format for dead-tree printers.

The first is Photoshop's licensing for Pantone colors to ensure accurate color matching. Adobe can pay to license Pantone's patented color specification; the all-volunteer GIMP Project cannot. There are GIMP palettes that approximate Pantone colors, but no one can say with certainty if these educated guesses are 100% right.

The second problem relates to the differences between how colors look on a computer screen and how they look in a magazine. The GIMP separates colors based on a combination of red, green, and blue (RGB) values. Print publishers use a scheme called CMYK (cyan, magenta, yellow, and "key," or black). In the short term, there is a GIMP plug-in called Separate that provides "minimal support for CMYK." For the long term, developers are working on a new technology, the Generic Graphical Library (GEGL), that will fully support CMYK color separation and other "deep color" issues.

If you produce images for print, these two issues may be critical, and you may need to keep a copy of Photoshop around. Be aware that you can run Photoshop under Crossover Office, the Codeweavers cross-platform tool.


Graphics Formats

When you work with digital images, there seems to be a million different formats. Despite what you may believe, each format exists for a specific reason, either technical, aesthetic, or legal/financial. Some formats are patented or have patented technology included.

When you're working with editors such as The GIMP, choose the right format for the task at hand. Following is a list of some of the more popular formats, followed by an explanation of why you might want to use (or not use) them.

  • BMP Bitmapped graphics, which are commonly used in Windows. They are large and uncompressed files, good for icons and wallpaper.

  • GIF Graphics Interchange Format. Most graphics on the web once used this format, developed by CompuServe, one of the original online services. GIF uses a patented lossless compression algorithm (LZW) that requires a license to use.

  • JPEG The Joint Photographic Experts Group developed this format for electronic photographs. All digital cameras produce this format by default. The compression scheme loses some data, but provides a sharp image nonetheless.

  • PNG Portable Network Graphics. The open source replacement for GIFs.

  • SVG Scalable Vector Graphics. The Next Big Thing, this web graphics standard is being developed by the World Wide Web Consortium (W3C).

  • TIF Tagged Image File. Often used for printing and publishing.

Sometimes you may not be able to work with a file in its current format. Coming to your rescue are a host of separate image-converter applications that can change an image's format almost instantly. The best known of these, ImageMagick, even does its thing from the command line!



SUSE Linux 10 Unleashed
SUSE Linux 10.0 Unleashed
ISBN: 0672327260
EAN: 2147483647
Year: 2003
Pages: 332

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