Fujitsu fi-5950 Operator's Manual page 211

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8.6 Page Edge Filler (ADF)
Unless otherwise specified, the background color is white. You can also
change it to the "Black background" using the scanner driver.
If you are using the TWAIN driver, do the following to change the background
color to black: Select the [Option] button, and then select [Black background]
from [Automatic Size and Skew detection] on the [Rotation] tab.
Note that if the Page Edge Filler is too wide, some characters in the vicinity
of the boundary may be cut out.
When "Automatic Page Size Detection" is set, "Page Edge Filler (Automatic
Page Size Detection)" automatically becomes valid instead of this setting.