Canon mp280 - Manual (Page 359)

The Stitch-assist window opens.
6. Place the left half of the document face-down on the Platen.
7. Click Scan.
The left half of the document is scanned and appears in the Stitch-assist window.
Note
Click Cancel to cancel the scan.
Page 359 of 707 pages Scanning Images Larger than the Platen (Stitch Assist)