Image Processing - Canon D1 Service Manual

2
Technology > Controls (Reader)

■ Image Processing

● Overview
The functions of image processing system's PCB are described below.
- Main controller PCB 2 CCD drive, analog image process, A/D conversion, shading
correction (executed per each job), shading adjustment (executed at
power-on)
- CCD PCB Analog image process, A/D conversion
The machine uses the main controller PCB to process images for every single image line.
Specific functions are as follows.
a. Main controller PCB 2
- Shading correction
b. CCD PCB (inside CCD unit)
- CCD drive
- CCD output gain correction, offset correction
CCD PCB
CCD(4lines )
Analog image
EEP- ROM
signal
CCD drive
control
Analog image
process A/D
conversion
- gain correction
- offset
correction
CCD/AP PCB
2 Technology > Controls (Reader)
Main controller PCB 2
ASIC
CCD
control
signal
Gain
correction
EEP- ROM
data
CPU
SRAM
Digital
image
Digital image
signal Shading
signal
correction/
adjustment
F-2-21
● CCD Drive
The machine's CCD sensor is a 4-line linear image sensor consisting of 7500 pixels. After
completion of photoelectric conversion in the light-receiving block, the signals are output to
the analog front end PCB unit on CCD PCB in parallel for each channel (R, G, B, B/W) of the
CCD array.
Red(R)line
Green(G)line
Blue(B)line
Black & white(B/W)line
Light-receiving block
● Gain Correction and Offset Correction of CCD Output
The analog video signal generated by the CCD is corrected so that it will have a specific level
(gain correction); moreover, the output voltage occurring in the absence of incident light is
also corrected so that it will have a specific level (offset correction).
● A/D Conversion of CCD Output
The corrected analog video signal is converted into a digital signal that is suited to the voltage
level of individual pixels by the A/D converter.
Expanse
Output
L L H H L H L H H H L
.........
F-2-22
2-10
2-10