Ricoh A-C2 - Auto Shading (Shading Correction); Background Erase

26 January, 2001 IMAGE PROCESSING
6-27
Detailed
Descriptions
Auto shading (shading correction)
Auto shading does two things.
• Zeroes the black level for each scan line of data
• Corrects for variations in white level across the main scan.
Background erase
By default, this process is used only in text mode, pale original mode, and
generation mode. However, it can be enabled for other modes with SP mode.
Usually, dirty background is erased using the Auto Image Density (ADS) function.
However, sometimes, dirty background areas will still appear. These can be erased
by this function.
If any low image density data which is lower than a threshold level remains after
auto shading, this data will be changed to “0” = white.
The threshold level (erase level) can be changed with the following SP modes.
65
Background Erase Level (Text)
66
Background Erase Level (Photo)
67
Background Erase Level (Text /Photo)
68
Background Erase Level (Pale)
SP4-903
69
Background Erase Level (Generation)