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APPENDIX B. OPTICAL ADJUSTMENT (ELECTRICAL)
B.2.2. Software
•
Terminal (One of the Windows Accessories)
B.3. Adjustments
•
GCA (Gain Control Amplifier) Gain Curve
This adjusts the GCA amplification ratio. The GCA on the SBU amplifies
analog image data.
•
White level difference between the even pixel and odd pixel channels of
the CCD
The even pixel channel output level is adjusted to equal the odd pixel
channel output level.
•
White level when scanning the white reference sheet (Absolute white
level)
The analog output level when the machine scans a white sheet is
adjusted.
•
White level for background detection mode (Relative white level)
This adjusts the analog ASIC peak hold value (used for generating the
reference voltage of the A/D converter). Analog image data is converted
to digital data using this reference voltage.
B.4. Adjustment Procedure
B.4.1. Setup
1. Make sure that the exposure glass has been removed and that the jig
glass has been placed on the scanner as shown below.
Note: The side of the glass with the charts attached should be facing
up, so that the charts are face down.
B-2
October 9th, 1995
g404x518.wmf
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