IMAGE PROCESSING
20 June 2005
6-38
Text Mode MTF Filter
This section describes how to select the MTF filter coefficient and filter strength for
the Text mode. You can use the SP mode settings listed in the table below to
adjust these items for scanning in Text mode:
•
MTF filter coefficient for the main scan and sub scan
•
MTF filter strength for the main scan and sub scan
Coefficient Strength
Text Mode
(Mag.)
Main Scan .
Sub Scan .
Main Scan .
Sub Scan .
25% ~ 64%
SP4903 20
SP4903 21
SP4903 22
SP4903 23
65% ~ 154%
SP4903 24
SP4903 25
SP4903 26
SP4903 27
155% ~ 256%
SP4903 28
SP4903 29
SP4903 30
SP4903 31
257% ~ 400%
SP4903 32
SP4903 33
SP4903 34
SP4903 35
Ranges
0 ~ 15
0 ~ 13
0 ~ 7
0 ~ 7
Strengthening the MTF filter sharpens the edges of text characters and improves
the appearance of low contrast text but can also cause moiré to appear in photos
on the same original.
Conversely, weakening the MTF filter softens the edges of text characters and
reduces the occurrence of moiré but low contrast characters may fade.
Strengthen or weaken the MTF filter for the Text
mode only when necessary.
Adjustment of the MTF filter coefficient performs
very fine level adjustment of the applied strength
of the MTF filter. Adjustment of the MTF filter
strength greatly affects the rate of the change
applied to the image. Basically, you should first
just the MTF filter strength in 1 step increments
without adjusting the coefficient to achieve nearly
the effect you want, and then use the coefficient
settings for fine adjustment.
Coefficient and strength adjustments for main
scan affect lines parallel to the direction of
scanning [A].
Coefficient and strength adjustments for sub scan
affect lines at right angles to the direction of
scanning [B].
B195D916.WMF
[A]
[B]
Scan Direction
