Canon DR-3080CII - Manual (Page 64)

62 Specifications
CAUTION
Always clean the scanning glass before calibrating the scanner
(see "Cleaning the Scanning Glass and Rollers" on p.55).
Attempting to calibrate the scanner while the scanning glass is
dirty may result in vertical lines appearing on scanned images.
Note that calibrating the scanner will permanently delete any
existing calibration configuration.
Locate the adjustment sheet (shading paper) that accompanies the scanner.
Load it into the scanner with the arrow pointing in the direction illustrated.
After loading the adjustment sheet, click the [Start] button in Windows, select
[Programs] - [Canon DR-3080CII] then click [DR-3080CII Shading Tool].
The [Scanner Adjustment] dialog box is displayed. Follow the instructions on
the screen to calibrate the scanner.
Adjustment sheet