Canon MG8100 series On-Screen Manual page 758

type.
Auto
None
Sharpening slightly out-of-focus images
Set Unsharp Mask to ON.
OFF
Reducing gradations and stripe patterns
Set Descreen to ON.
OFF
Note
Printed photos and pictures are displayed as a collection of fine dots. "Moire" is a phenomenon
where uneven gradation or a stripe pattern appears when such photos or pictures printed with fine
dots are scanned. Descreen is the function for reducing this moire effect.
Reducing dust and scratches
Set Reduce Dust and Scratches to Low, Medium or High according to the degree of dust and scratches.
None
Note
When the resolution is set to 4801 dpi or higher and Reduce Dust and Scratches checkbox is
selected, images are scanned at an optical resolution of 4800 dpi then interpolated by the software
to yield the specified resolution.
ON
ON
Medium