How Input Determines Output - Xerox DocuColor 5252 Operator's Manual

How input determines output

Scanners
Do c u Co lo r 52 5 2 O pe r a to r Ma n ua l
Successful reproduction of color images depends on a number of
factors, starting with the differences in how the various
technologies that affect the image translate and display the color.
Scanners are able to capture colors only as red, green, and blue
(RGB). Two types of scanners are used today: drum and flatbed
scanners. A flatbed scanner does not have as much color range
as a drum scanner.
• A drum scanner uses a photomultiplier tube (PMT) that is very
sensitive and accurate. The original document is attached to
the drum which is rotated past a group of sensors - one each
for red, green, and blue, and a fourth that sharpens the digital
image. An internal computer usually performs the RGB to
CMYK (cyan, magenta, yellow, black) conversion.
• Flatbed scanners use a less expensive and less accurate
charge coupled device (CCD) sensor. The original is placed on
a flat glass surface and the array of CCD sensors passes by
the original, and collects the red, green, and blue data. RGB to
CMYK conversion is usually performed on a computer
workstation.
Key point: The resolution at which the image is initially scanned
and digitized determines the quality of the final output and limits
the degree to which the image can be enlarged without loss of
final printed quality.
A bo u t c o l or pr in ti n g
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