Ricoh C226 Service Manual page 65

OPTICS/IMAGE PROCESSING
Main Scan Magnification
80% Reduction
Scanned Data
Points
Calculated Data
Points
Reduced Image
Data Points
140% Enlargement
Scanned Data
Points
Calculated Data
Points
Enlarged Image
Data Points
Reduction and enlargement in the sub-scanning direction is done by
changing the original transport motor speed. Reduction and enlargement in
the main scanning direction is handled by the magnification and image shift
processing.
Pixels for scanning and master making are generated at fixed intervals (the
contact image sensor and thermal head element intervals). The image is
scanned at the contact image sensor element interval. If pixels on the master
are made at the same interval (by the thermal head elements) then the
master image is the same size as the original.
80 % Reduction
For example, data for 10 pixels in a main scan line are scanned by the
contact image sensor. Those data are compressed into data for 8 pixels by
the magnification processor. As a result, the image is reduced to 80 %.
140 % Enlargement
Data for 10 pixels of a main scan line are expanded into data for 14 pixels. As
a result the image is enlarged with a 140 % magnification ratio.
When actual pixels are divided in accordance with a magnification ratio, the
values of the imaginary points that would correspond to new pixels are
calculated by the magnification processor. The proper value for each
imaginary point is calculated based on the image data of the surrounding
pixel values.
NOTE: The magnification ratios of 80% and 140% are not available in
the C226. They are used for the ease of explanation.
C226 2-16 SM