Creo CXP6000 Color Server, User Manual

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486 Spire CXP6000 Color Server User Guide
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 Continous Tone images,
misregistration can lead to blurring. See also
Overprinting 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.