Black Level Correction - Ricoh B202 Service Manual

IMAGE PROCESSING

Black Level Correction

• Improves image reproduction for high-density areas.
• Reads the black video level at black elements on the CCD. These pixels are
masked off, and should produce a pure black signal.
• This is subtracted from the value of each pixel.
• Calculated for each scan line.
• Corrects the image data for any changes in black level with time, as the machine
scans down the page.
Adjustments
The properties of the scanner unit, (necessary for controlling the scanner VPU
(video processing unit)), are stored in the NVRAM on the controller.
Adjust the following after you replace the SBU:
SP4–008 Scanner sub-scan magnification
SP4–010 Scanner leading edge registration
SP4–011 Scanner side-to-side registration
VPU Test Mode
Output the VPU test pattern with SP4-907 to make sure the scanner VPU control
functions correctly. (
B202/B178/B180
"4. Troubleshooting" for details)
6-26 SM