Digital Image Processing - Oce 3121 Technical & Service Manual

3 Digital Image Processing

Outline
The digital image processing serves to process image signals from various
PBA.
Shading Correction
The output of the CCD will not be constant for the following factors (even
when the light reflected by a document with even density is projected to the
CCD).
The sensitivity of each pixel of the CCD is not the same.
1
The variations of the lens: centre versus edges.
2
The variations of the exposure lamp, between the centre and the ends.
3
The exposure lamp can deteriorate.
4
Shading correction is performed to correct the above discrepancies. Shading
correction may be executed for each copy, or executed automatically, accord-
ing to the target value determined in service mode.
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