134 Graphic Communications
output station consists of two parts, the raster image
processor and the digital output device. The digital
output device can be used to output high-resolution
text and graphic images onto paper, plates, or directly
to a digital printing press.
The raster image processor (RIP) converts all
elements of a page or image into a bitmapped image
at the resolution of the selected output device. The
RIP interprets the page composition information for
the marking engine of the output device, such as an
imagesetter, platesetter, digital printer, or large format
devices, Figure 7-12. Output problems are most
likely to occur during the ripping process. It is usually
the responsibility of the operator to troubleshoot
these problems. However, if the fi les have not been
properly prepared, they may need to be returned to
the point of origination for correction.
Page Description Languages (PDLs)
A page description language (PDL) serves
as the interface between the page composition
workstation and the RIP. PDLs are used in digital
publishing to identify all the elements to be placed on
the page, their respective positions on the page, and
the page’s position within the larger document, in a
manner that the output device can understand. PDLs
enable digital output devices developed by different
companies to interpret digital fi les from any number
of personal computers and software programs.
Common PDLs include Adobe® PostScript®, Adobe®
PDF (Portable Document Format), and Hewlett-
Packard PCL (Printer Control Language).
An interpreter is a computer program used with
output devices that receive the PDL page descriptions
and translates them into patterns of dots for a
printer or pixels for monitor display. After receiving
a page description, the interpreter constructs a
representation of the page to suit the output device.
For example, the interpreter can determine whether
the output device is a black-only or color printer,
an RGB video monitor, or a 2400 dpi platesetter.
Once these parameters are defi ned, the interpreter
modifi es its instructions accordingly.
Preparing
Content
Software used with digital imaging systems is
classifi ed by its role in the digital prepress process.
This process essentially consists of preparing content,
composing pages, and outputting the fi nished fi le to
an imagesetter, a platesetter, or directly to a digital
press. The software used in prepress work consists of
word processors, draw and paint software, graphics
editors, and page composition programs.
Figure 7-11. For highest quality output on photopaper
or fi lm, an imagesetter is used. This imagesetter offers
six resolution settings ranging from 1000 dpi to 3000 dpi,
and can output material up to 22″ (56 cm) in width.
(Fuji Graphic Systems)
Figure 7-12. With the addition of an add-on device,
many imagesetters are able to create plates as well as
fi lm. (FUJI Photo Film U.S.A., Inc.)