10 August, 2001 IMAGE PROCESSING
2-7
Detailed
Descriptions
2.2.3 AUTO IMAGE DENSITY
ADS prevents the background of an original from appearing on copies.
The copier scans the auto image density detection area [A] as shown in the
diagram. This corresponds to a few mm at one end of the main scan line. As the
scanner scans down the page, the SBU detects the peak white level for each scan
line. The IPU performs the ADS function in accordance with the peak white level.
When an original with a gray background is scanned, the density of the gray area
is the peak white level density. Therefore, the original background will not appear
on copies. Because peak level data is taken for each scan line, ADS corrects for
any changes in background density down the page.
As with previous digital copiers, the user can select manual image density when
selecting auto image density mode, and the machine will use both settings when
processing the original.
80mm
20mm
0.5mm
Sub scan direction
B027D552.WMF
[A]
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