Filter/Magnification - Konica Minolta Bizhub 501 Service Manual

22. IMAGE PROCESSING
22.1.5

Filter/magnification

A. Filter processing
An appropriate filter processing is made according to the type of an original and the magnification selected.
(1) Character : Make the shading of an original conspicuous.
(2) Dot section : Suppress moire.
(3) Picture : Increase the reproducibility of gradation.
B. Magnification processing
For this machine, the sub scan direction magnification is made by the scan speed of the exposure unit (platen
mode) or by the conveyance speed of the DF (DF mode), and the main scan direction magnification is made by
processing images electrically.
(1) Main scan magnification processing while in enlargement
As shown in the drawing below, if the data of each pixel obtained when the original is read by the CCD are D1 to
D5, the positions of the data read when enlarged are E1 to E5. However, when the write is made only with the
data thus read, the following problems occur.
a. There occurs a clearance between data, and this results in a distorted image.
b. The data position does not fall in exactly with the write position.
As shown with dotted lines in the drawing below, when there is no read data that corresponds exactly to the
write position, a density is decided for the write as shown below and appropriate processing is made.
[1] Position at which the original is read
[2] Data position while in enlargement
94
[1]
D1 D2 D3 D4
[2]
E1 E2
[3]
W1 W2 W3 W4
Theory of Operation Ver.2.0 Mar. 2009
D5
E3 E4 E5
W5 W6 W7 W8
[3] Write position
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