Canon MultiPASS F20 Software User's Manual page 77

2. If you are working with a color image, click the appropriate color
channel.
3. Move the Contrast and Brightness sliders to the left for less contrast
or brightness, and to the right for more contrast or brightness.
4. To return to the original setting, click Reset.
To adjust the tone with the gamma value:
1. On the Tone tab, click Gamma.
Chapter 4 Scanning 73