How Input Determines Outpu - Xerox DocuColor 2060 Operator's Manual

How Input Determines Output
Scanners
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D O C U C O L O R
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.
O P E R A T O R M A N U A L
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B O U T O L O R R I N T I N G
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