Oce TC4 User Manual page 37

Setting
'Mirror'
'Lighter/darker'
Description
Use this setting to create a mirrored image of an original.
Mirroring occurs in the transport direction. (The image
is mirrored along the vertical axis.)
Use this setting to define the exposure of the original.
Negative values mean less exposure and darker scanned
output. Positive values mean more exposure and grayer
scanned output.
Note:
This setting can only be set if the color mode
you select is gray or black and white.
Available settings for scan-to-file jobs
Chapter 2 - Use the Océ TC4 37