Xerox DocuColor 5252, Operator'S Manual

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DocuColor 5252 Operator Manual
2-9
About color pr inting
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Adding and replacing gray to improve color
There are limitations to achieving the exact colors when
converting from RGB (for video display) to CMY (for
print). For example, CMY pigments aren’t capable of
producing consistent black or gray tones.
In cases in which the three ink or toner colors overlap
heavily, software applications automatically vary the
percentages of cyan, magenta, and yellow to enhance
image quality and improve printability. This technique is
known as undercolor removal, or UCR, in which black ink
is used to replace cyan, magenta, and yellow ink in
neutral areas only (that is, areas with equal amounts of
cyan, magenta, and yellow). This uses less ink and
provides greater depth in shadows. UCR is generally
used for newsprint and uncoated stock
Another form of undercolor removal is called Gray
Component Replacement (GCR). To compensate for the
neutral or grey tones created during the conversion of
RGB to CMYK, black ink replaces portions of cyan,
magenta, and yellow ink in colored areas, as well as in
neutral areas. GCR separations tend to reproduce dark,
saturated colors somewhat better than UCR separations
do, and they maintain gray balance better in print.
UCR
UCR
UCR
No GCR
Light GCR
Medium GCR
Maximum GCR