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Gimp: Printing &
Gimp, CUPS and Gutenprint are a fellowship that can lead you on your quest for high quality prints – Michael J Hammel continues his graphics tutorial series.
this language directly, whereas non-compatible printers must have data converted into a custom printer language. Getting files intoPostScript in the first place is a multi-step process that involves a series of software packages. The Linux printing environment is made up of four levels of software: drivers, spoolers, filters and applications. Printer drivers form the backbone of printing; they send data to the printer using a language the printer will understand. Some Epson printers, for example, use a language called ESC/Pwhile other manufacturers use a language called PCL. The data must already be in that language when the driver receives it, however; the drivers are not responsible for doing any data conversions.

CUPS and Gutenprint
Printer drivers for Linux come primarily from the Gutenprint and/or Ghostscript projects, although HP have their own set of drivers (known as the HPIJS) that they actively support.Other vendors, including Epson, offer drivers for their printers as well. All of the drivers are intended to be fed data to print via the various Linux print spoolers. Drivers are at the bottom of this four-layer software stack for printing. At the opposite end are applications, with spoolers just below. When an application is directed to print a file, it sends it to a print spooler, which queuesit up to be processed later (when the spooler is not busy with other print jobs). There are many spoolers available for Linux, including LPR (Line Printer Remote), LPRng and CUPS (Common Unix Printing System). CUPS is becoming the standard for spoolers on Linux distributions for a variety of reasons, although none of these make much difference to end users. It’s important to note that you’ll beworking with CUPS to set up your printers. Once a spooler has a file queued for printing, it runs the file through one or more filters that convert it into various formats. The filtering process is better know as a ‘RIP’ (Raster Image Processing). In some cases the files need to be converted into PostScript first, then into a printer-specific format before being sent to the printer driver. In othercases the file may already be in PostScript format, or may not need to be converted to another form before being sent to the printer driver. Filters can come from a number of software packages. The most widely used set of filters come from the Foomatic package, but you won’t need to worry about them much because you’ll get the ones you need when you install CUPS. With all that software ready andunder the hood, it’s time to configure your printer. As well as checking the OpenPrinting website (www.linuxfoundation.org/openprinting) to see if the printer is supported, you’ll also want to install CUPS. CUPS is both a spooler and a configuration tool. It allows you to configure your printers whether they’re directly connected to your system, located on your local network or connected to anothersystem elsewhere

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contributor to the Gimp project and the author of three books on the subject, including his latest, The Artist’s Guide to Gimp Effects.

Michael J Hammel is a

ver since the birth of Gnome and KDE, printing support has been the bane of the Linux office desktop user. Advances in 2D and 3D graphics have been phenomenal thanks to the requirements of the specialeffects industry in Hollywood, yet with high-quality futuristic displays at our doorstep, we still settle for Stone Age prints. Until recently, the lack of a unified printing system has meant that desktop applications have either implemented their own printing features or relied on the lowest common denominators, often leading to low-quality prints or, even worse, no facility for printing at...