Filtering, Main Scan Magnification/Reduction - Gestetner A294 Service Manual

2.3.8 FILTERING, MAIN SCAN MAGNIFICATION/REDUCTION

Overview
After auto shading, the image data is processed by both filtering and main scan
magnification. However, to reduce the occurrence of moiré in the image, the
processing order depends on the reproduction ratio, as follows.
1. 64% reduction or less
Main Scan Reduction → Filtering
2. 65% reduction or higher
Filtering → Main Scan Magnification
Filtering
By default, an individual MTF filter is used for each image processing mode, to
enhance the desired image qualities. (For Photo mode, smoothing filter is selected
as the default setting.)
A stronger MTF filter emphasizes sharpness and leads to better reproduction of
low image density areas, but may leads to the occurrence of moiré in the image.
The MTF filter strength can be changed by changing the coefficient (MTF Filter
Level) and strength of the MTF filter in combination using SP mode. Refer to the
combination chart in 'Image Quality Setting by UP Mode' in section 4. The filter
coefficient and strength can be adjusted in the main scan and sub scan directions
individually. This allows the copy quality to be adjusted more precisely, to match
the originals normally scanned by a particular customer.
Example: In a case when vertical lines (sub scan) are reproduced clearly, but
horizontal lines (main scan) are not reproduced clearly, the technician
can adjust the main scan filter only.
For photo mode, the smoothing filter is the default filter, but the MTF filter may be
selected by SP mode 4-903-9. This is effective when putting more weight on
improving the resolution when copying from "continuous tone" originals.
SM
CÓPIA NÃO CONTROLADA
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CÓPIA NÃO CONTROLADA
IMAGE PROCESSING
A294/A295