Canon Color imageCLASS MF8170c Software Manual page 233

Scanned image is displayed at a larger (smaller) size on the computer screen.
Q
A
5
5-10
Scanning Problems
Is the resolution setting correct?
Do one of the following:
1. Enlarge or reduce the image display in the application.
However, if you open the image in [Paint] or [Imaging], it may display at a
large size and you will not be able to reduce it.
2. Change the resolution and scan again.
The image will be large if resolution is high. It will be small if resolution is low.
(See "Determining Resolution," on p. 3-42.)