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.
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 Wndows. 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 Wde 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!
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