Canon MultiPASS L6000 Software Manual page 141

2. To automatically compensate for common problems in an image,
select one of the options from the list.
Using a Custom Tone Curve
If you want to experiment with tones, you can create a custom tone
curve. An effective way to do this is first to adjust the preview image
with an appropriate predefined tone curve, and then edit the results.
Editing a tone curve involves adding handles to an existing tone curve
and dragging them to change tonal levels in the image. When you drag a
handle to a white area, the shape of the curve changes, and the tones of
the preview image are adjusted.
All handles on the tone curve, including the end points, can be dragged
anywhere within the tone graph. A handle that is dragged outside the
tone graph is deleted; and the tone curve automatically conforms to the
remaining points. Except for the end points, all handles can be deleted.
Chapter 6 Scanning 6-23