Improving Ghostscript Output

Traditionally, Unix computers have used PostScript printers. This fact has greatly simplified the design of traditional Unix print queue systems such as BSD LPD and LPRng because these systems don't need to support extensive printer drivers, as are common in Windows and other OSs. Instead, applications produce PostScript output, which is fed more-or-less intact to the printer by the printer queue. This approach does have disadvantages, though, such as the fact that applications can't query a printer queue for detailed information about a printer's capabilities. One drawback that's more important for an average Linux system than for more traditional Unix workstations is that a Linux system is likely to be paired with a non-PostScript printer. Such inexpensive printers typically can't parse the PostScript output directly. Linux's solution is to call Ghostscript from the print queue. This program converts PostScript into a variety of other formats that can be displayed in graphics programs or processed by a printer. Effectively, Ghostscript becomes the printer driver on a Linux system. Another way of looking at the situation is that Ghostscript is a PostScript interpreter that runs on the Linux system rather than on the printer.

In order to get the most from Ghostscript, you must know how to configure it. This task includes knowing where to look to change the Ghostscript calls, knowing which Ghostscript driver to use, and knowing which driver options to use. You may also want to create multiple print queues to provide access to different printer features.

Warning Some printers that don't understand PostScript are marketed as PostScript printers. These printers use computer-based PostScript interpreters much like Ghostscript. Such a method does Linux no good, unless of course the drivers are available for Linux or the printer is used via a Windows print server. If you're shopping for a new printer and want PostScript capability, be sure the PostScript interpreter is built into the printer.

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