Canon PIXMA MG4200 Series On-Screen Manual page 679

Zoom rescans the image and displays high-resolution image in Preview.
(Enlarge/Reduce) on the Toolbar zooms in on the preview image quickly. However, the
resolution of the displayed image will be low.
Preview
Performs a trial scan.
Scan
Starts scanning.
Note
When scanning starts, the progress will be displayed. Click Cancel to cancel the scan.
When scanning is completed, a dialog prompting you to select the next action may open. Follow
the prompt to complete. For details, see Status of ScanGear dialog after scanning in
Tab" (Preferences dialog).
It will take time to process the images if the total size of the scanned images exceeds a certain
size. In that case, a warning message appears; it is recommended that you reduce the total size.
To continue, scan in whole image view.
Preferences...
Opens the Preferences dialog in which you can make scan/preview settings.
Preferences Dialog
Close
Closes ScanGear (scanner driver).
(2) Toolbar
Toolbar
You can adjust or rotate preview images. The buttons displayed on the Toolbar vary by view.
In thumbnail view
"Scan