Canon imageFORMULA R40 User Manual page 67

Problem 12 The size detection and deskew functions fail.
Solutions When [Carrier sheet] is set to [Carrier sheet] in the
[Feeding] tab of the scanner driver settings screen and
you scan a document with black edges without
inserting it in a carrier sheet, the size detection and
deskew functions may fail. In such cases, disable the
size detection and deskew functions, or set [Carrier
sheet] to [None] in the [Feeding] tab.
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