Canon F-1, Service Manual

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Technology > Controls > Reader > Image processing
Technology > Controls > Reader > Image processing
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Magnification change
● Magnification change in main scanning direction
In main scanning direction, image is always scanned by 100% size at copyboard scanning
and DADF scanning, and then magnification is changed at image processing on the main
controller block.
● Magnification change in sub scanning direction
In sub scanning direction, image is always scanned by 100% size at copyboard scanning
and DADF scanning, and then magnification is changed at image processing on the main
controller block.
At image SEND, reading size is changed by 100% or 50% depending on the specified
resolution.
Service Mode
(Lv.1) FEEDER > ADJUST > ADJMSCN1
Zoom adj in 2-sided main scan way: front
(Lv.1) FEEDER > ADJUST > ADJMSCN2
Zoom adj in 2-sided main scan way: back
(Lv.1) FEEDER > ADJUST > ADJSSCN1
Zoom adj in 2-sided sub scan way: front
(Lv.1) FEEDER > ADJUST > ADJSSCN2
Zoom adj in 2-sided sub scan way: back
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Image processing
● Overview
Following is the main functions of image processing system.
• Reading sensor Number of lines: 4 (R, G, B, B/W)
Number of photo cells: 7488 (each line)
• Shading processing Shading adjustment In service mode
Shading correction Performed per very copy
Scanner unit PCB Reader controller PCB
Reading
sensor
Shading processing
Analog
image
processing
Analog image
processing block
Controller block
Digital image
processing block
A/D
conver-
sion
Following is functions of each PCB of image processing system
Scanner unit PCB: Analog image processing, A/D conversion
Reader controller PCB: Drive of scanner drive unit, shading correction
Error code
E248 Error in EEPROM
-0001 Error when EEPROM power supply for reader controller PCB (PCB1) is charged.
-0002 Error during EEPROM for reader controller PCB (PCB1) is written.
-0003 Error during EEPROM for reader controller PCB (PCB1) is read after being written.
E423 Error in SDRAM
-0001 Error in the SDRAM access.
-0002 Error in the SDRAM verification.
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Processing on the scanner unit PCB
Reading sensor output gain correction, offset correction
The analog video signal from the reading sensor is processed so that the rate of amplification
is even (gain correction) while the output voltage in the absence of incident light is also
processed for a specific level (offset correction).
Reading sensor output A/D conversion
The odd-numbered and even-numbered pixel analog video signals after the foregoing
correction are then converted into 10-bit digital signals by the A/D converter according to their
pixel voltage levels.
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