Xerox CX240 User Manual page 265

Glossary
Misregistration
Moiré
Newton's rings
OPI
Output resolution
Output tone curve
Overprint
PDL
A situation common during printing where one or more of the color
separations is slightly misaligned with regard to the others on press.
Misregistration shows up as white gaps or tinted overlaps at the
borders of color pairs. Colors containing such files are trapped to
compensate for this possibility. On Continous Tone images,
misregistration can lead to blurring. See also Overprint and Trapping.
An interference pattern caused by differences in halftone screen
angles or rulings. In process color printing, screen angles are selected
to minimize this pattern. If the angles are not correct, a pattern that
distracts the eye from the picture may be produced.
Small concentric circles that can appear on film when two surfaces are
closed together but not in perfect contact.
Abbreviation of Open Prepress Interface. A prepress convention
established by Aldus Corps. OPI refers to tags or place holders in
source PostScript that point to TIFF or EPS images that have not been
embedded in the PostScript. These images reside in other locations
and are merged with the PostScript file when processed. Normally
used for performing high res/low res image substitution (alternative
to Creo APR).
The number of laser dots per unit of linear measurement (millimeter,
inch etc.) on film or paper.
A graph showing the relationship of original input densities and the
corresponding dot percentages on film.
A technique, which overlaps colored elements to eliminate the
appearance of gaps between elements caused by misregistration of the
various separations during printing. For example, black text is
normally set to overprint. See also Trapping and Misregistration.
Printer Description Language files (for example, PostScript, PDF,
EPS, VPS, VIPP). The CXP Color Server processes image files in PDL
formats, converting them into a suitable Ready-To-Print format for
direct, high-quality printing.
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