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IMAGE-PROCESSING
Original Background Correction
When an original is scanned, the whitest level of the original background is stored,
and that level is used as the white peak level for A/D conversion. The grayscale is
made based on the white peak level of the original. As a result, dark background
does not appear on the printout.
If the original background correction is disabled, the whitest level when the white
plate is scanned is used for the high reference voltage.
Peak Hold
The peak hold circuit holds the voltage for the white peak level. Before scanning an
original, it holds the white peak voltage from the white plate to make shading
distortion data. When the original is scanned, it stores the white peak level of the
original for the original background correction.
NOTE: The white peak level is checked 5 mm from the leading edge of the original
set on the exposure glass (and from the central 147-mm width). If the
original leading edge is not flush with the original scale and the platen
cover stays open, insufficient voltage will be input as the white peak level.
If insufficient voltage is detected, a fixed voltage is used as the white peak
level to avoid a faint image copy.
C231
2-12
C231D512.WMF
SM
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