White Line Erase; Black Line Erase - Ricoh K-C1 Service Manual

IMAGE PROCESSING 20 February, 2001

White Line Erase

Since this machine does not apply white level correction as default, white lines are
automatically minimized (the reason is explained above). However, with no white
level correction, the images on the edges of the copy would always appear darker
than those in the center. This is because the CCD elements on the edges receive
less light. Therefore to compensate, SP4-941 can be used to control both the
uniformity of the edge/center image density and to minimize white lines. However,
it is a trade-off between the two:
SP4-941 applies the correction only to the output from the central CCD elements
only, keeping the output from the edge elements constant (as the standard). With a
setting of 1, a large amount of correction is applied and the central areas are
uniform with the edges. However white lines are relatively visible. With the
maximum setting (5), no correction is applied and the central areas appear lighter
than the edges (true to the original CCD data). However white lines are minimized.
Note that if SP4-941 is set to 0, white line erase is not used, and white level
correction is used instead.

Black Line Erase

In ADF mode, if extremely low CCD output is detected on the scanning line before
the leading edge of original arrives there, this is attributed to abnormal black dots
on the exposure glass. This low output is corrected using neighboring pixels. To
adjust or switch off this correction, use SP4-942.
6-22