User`s manual

Reference: The Preview Window 29
Overview Setup
This command lets you set the area you want to overview off the scanner bed
and provides some overview options as well.
By default, ScanWizard Pro overviews the maximum scan area as determined
by your scanner model's bed size. You can, however, customize the overview
area so that the scanner consistently overviews only the specific dimensions
you have in mind. For example, if your maximum scan area is 8.5" x 14", you
can customize the overview area so that it consistently overviews, say, 4" x 8"
of the bed size.
As a rule of thumb, it is best to use the default maximum settings. You should
change the overview area only if your subsequent overview is too large to be
shown in entirety, or too small for reliable previewing. A smaller overview area
will increase the overview resolution for clearer image viewing. You may also
wish to change the size of your overview to improve performance. Generally, a
shorter overview time results from the scanner motor travelling a lesser
distance.