Ricoh LD013, Service Manual

Page: 218 / 513

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IMAGE PROCESSING
SM 6-25 B039/B040/B043
Filtering
Overview
There are several software filtering processes for enhancing the desired image
qualities of the selected original mode. There are three MTF filters, a smoothing
filter, independent dot erase, and line width correction. Each can be used only
when certain modes are selected (details below) and are automatically applied.
The strength levels for the MTF and smoothing filters are controlled by SP4-925.
The levels for independent dot erase and line width correction are controlled by
SP4-927 and 4-928, respectively.
The MTF filters bring out sharpness. The three MTF filters are Edge, Solid Image
and Low ID Line. Independent dot erase removes unwanted dots from the image.
Line width correction adjusts the line width.
MTF Filter Adjustment - Edge
In order to determine whether a given dot is part of an edge or not, the IPU checks
all surrounding dots (vertical, horizontal, and diagonal). If the IPU determines that
the dot is part of an edge, the machine applies the MTF filter for edges, using the
value set in SP4-925-001. The higher the setting, the sharper the image. However,
this is only used when the customer uses Text 1, Text 2, Photo 1-3, Special 1,
Special 2, or Special 5.
The default value is “0” for each mode. However the actual strength of “0” differs
from mode to mode.
MTF Filter Adjustment - Solid
If the IPU detects that the dot is not part of an edge, the machine applies the MTF
filter for solid areas using the value set in SP4-925-002. The higher the setting, the
sharper the image. However, this is only used when the customer uses Text 2 or
Special 1.
The default value is “0” for each mode. However the actual strength of “0” differs
from mode to mode.
MTF Filter Adjustment - Low ID Line
The IPU also checks the image density of all dots. If a succession of low-density
dots is detected, the machine interprets this as a low ID line and applies the MTF
filter for low ID lines, using the value set in SP4-925-003. The higher the setting,
the sharper the image. However, this is only used when the customer uses Text 1,
Text 2, Photo 2, Special 1, Special 2, or Special 5.
The default value is “0” for each mode. However the actual strength of “0” differs
from mode to mode.