Canon iR8500 Service Manual page 147

CHAPTER 2 NEW FUNCTIONS
b. ABC Circuit
A colored background is identified as being white by changing the height of the dynamic
range according to the chromatic level of the background as shown in the following figure
for the CCD output level (8bit) of digital image signals (A/D converted).
Surface of original
FFh (white)
Output level
00h (black)
COPIER>FUNCTION>CCD>CCD-ADJ (shading auto adjustment)
Execute the mode after replacing the CCD unit, scanning lamp, reader con-
troller PCB, or standard white plate.
2-92
White Background Original
A : dynamic range of white-background original.
B : dynamic range of colored-background original.
F02-503-04
COPYRIGHT© 2001 CANON INC.
Colored Original
A
B
2000 2000 2000 2000
FFh (white)
00h (black)
CANON iR8500/7200 REV.1 AUG. 2001