Ricoh B245-62 Service Training page 39

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 are controlled by SP 4932. The
levels for line width correction and independent dot erase are
controlled by SP 4927 and 4928, respectively.
The MTF filters bring out sharpness. The three MTF filters are
Edge, Solid Image and Low ID Line. Line width correction adjusts
the line width. Independent dot erase removes unwanted dots from
the image.
(Continued in notes.)
Slide 39
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 SP 4930. 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 SP 4931. The higher the setting, the sharper the image. However, this is only used
when the customer uses Text 2.
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 SP
4932. 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.
Independent Dot Erase
When the user selects Text 1 and 2, Photo 2, and Special 1, 2, and 5 modes, independent dots are
detected using a matrix and erased from the image. The detection level can be adjusted with SP 4928.
The higher setting, the greater number of dots the machine will erase. The machine erases the dots
regardless of their image density. However, note that dots in mesh-like images may be mistakenly
detected as independent dots.
Line Width Correction
When the user selects Text 1 and 2, Photo 2, Special 1, 2, and 5, the thickness of lines is adjusted using
the setting of SP4-927. Note that the default for all modes except Special 2 is OFF.
Line width correction is done by the IPU (SCRATCH) chip.
Filtering
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B245-62 / PD-C4