Main Scan Magnification - Ricoh C231 Service Manual

IMAGE-PROCESSING

2.2.4 MAIN SCAN MAGNIFICATION

Scanned Data
Points
Calculated Data
Points
Reduced Image
Data Points
Scanned Data
Points
Calculated Data
Points
Reduced Image
Data Points
Changing the original transport speed performs the reduction and enlargement in
the sub-scanning direction. Reduction and enlargement in the main scanning
direction is handled by the magnification and image shift processing circuits.
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.
When actual pixels are divided in accordance with a magnification ratio, the
magnification processor calculates the imaginary point values that would
correspond to new pixels. The proper value for each imaginary point is calculated
based on the image data of the surrounding pixel values.
- 80 % Reduction -
For example, the contact image sensor scans data for 10 pixels in a main scan
line. 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.
C231
2-16
C231D520.WMF
SM