3 December 2004
IMAGE PROCESSING
6-11
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etailed
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escr
iptions
6.7.2 IMAGE PROCESSING IN THE SBU
The CCD converts the light reflected from the original into an analog signal. Each
analog signal is transmitted to the analog front end IC.
The analog front end IC does the following operations.
1. Z/C (Zero Clamp)
Adjusts the black level reference for even-numbered pixels to match the odd-
numbered pixels.
2. Signal Amplification
Operational amplifiers in the AGC (Auto Gain Control) circuit amplify the analog
signal. The CPU on the MCB board controls the maximum gain.
After the above processes, the analog signals are converted to 10-bit digital signals
by the A/D converters.
The shading function corrects these signals. Shading correction prevents uneven
images caused by fluctuations in scanned data due to changes in light intensity
and CCD sensitivity.
6.7.3 IMAGE PROCESSING IN THE MCB
The CPU on the MCB is the image processor. It does the following:
1. Scan line correction
2. White level correction
3. Gamma (
γ
) correction
4. Line skipping correction
5. Mirroring for ADF Mode
6. Magnification
7. Color resolution
8. Background Erase
9. Auto binary processing
10. Auto image area separation
11. Filtering
12. Scale processing
