Canon GP160DF, Service Manual

Page: 81 / 797

COPYRIGHT © 1999 CANON INC. CANON GP160 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE PROCESSING SYSTEM
4-7
C. Magnification ratio process
The magnification ratio in horizontal scanning direction (drum axis direction) is
changed by line skipping (for reducing) when writing the image signal to the line memo-
ry, or double scanning (for enlarging) when reading out from the line memory.
The magnification ratio in the vertical scanning direction is changed by increasing
the speed of the mirror mount’s movement (when reducing), or reducing the movement
speed (when enlarging).
D. Edge emphasis / smoothing process
When the character mode is selected on the control panel, edge emphasis process-
ing takes place. When the photo mode is selected, smoothing processing takes place.
When edge emphasis processing takes place, it is possible to emphasize an image’s
gradation variations thus producing a more distinct image. Conversely, the smoothing
process softens the image’s gradation variations, and produces a softer image. When
copying a photo, the smoothing process makes the moiré effect less conspicuous.
Figure 4-304
0
100
200
255
Black
White
1 pixel
Horizontal scanning direction
After output
0
100
200
255 Black
White
Horizontal scanning direction
After output
Smoothing process
0
100
200
255 Black
White
Horizontal scanning direction
After output
Edge emphasis process