The scanned image is skewed.
To prevent the image skew problem, adjust the paper guides of the paper tray to fit the document width before the scanning operation.
For your information
These scanners output the scanned images in each document size. Also, when the documents are skewed and fed through the ADF, the scanned images are corrected to be straight automatically.
The scanner may not work properly with the application software which does not support the "ICAP_AUTOMATICBORDERDETECTION" TWAIN API.