Xerox 242 - Manual (Page 251)

Glossary 243
Ink jet proof A proof of a digital image printed by using jets that squirt minuscule
drops of ink. Ink jet proofers can print onto a variety of surfaces.
Job Flow Job flow refers to the job parameter settings of selected virtual printers
that are automatically applied to all jobs printed using that virtual
printer. These settings determine how a sent or imported file is
processed. For example, a file sent to a virtual printer with a Process &
Print job flow will be RIPped, printed and stored in the Storage Folder.
A file sent to a Process & Store job flow virtual printer will be RIPped
and stored, without printing.
LEF A printer page orientation, where pages are delivered long edge first.
Laserwriter driver A part of the Macintosh system software which generates PostScript
instructions from an application file when the Print command is
activated.
Look-up table (LUT) A two or three-dimensional array of values stored for specified input-
output relationships. When one input value is known, the system can
automatically determine the correct output value. For example, the
system can find the needed dot size for a given set of printing
conditions based on the stored gray level; color setups can be saved in
color tables (color transformation tables) which are one of the many
kinds of LUTs.
Linework Linework graphics are characterized by sharply defined lines and very
clear transitions from one color to another. Linework is stored in the
computer as a series of geometric (vector) drawing instructions.
Metamerism Metamerism occurs when two colors match under one light source,
but appear different under another light source. Those two colors are
called a metameric match. A metameric match might cause problems
when trying to match proofs to press-sheets under different lighting
conditions.
Midtones Density values of an image (original or reproduction) between the
highlights and the shadows. In the reproduction, midtones are printed
with dot areas between approximately 40% or 60%. See also
Highlights and Shadows.
Misregistration 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 Continuous Tone images,
misregistration can lead to blurring. See also
Overprint and Trapping.
Moiré 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.
Newton's rings Small concentric circles that can appear on film when two surfaces are
closed together but not in perfect contact.