Scanners never feed paper straight thru. As fine as a stack of paper is prepared, the pages never are 100% aligned and the mechanics grab the paper with and additional jitter. Most pages are scanned with more or less skew.
Stacks with mixed size or non-standard documents additionally contribute to images with a surrounding padding. The resulting files are unfriendly to the human eye, an adventure for a OCR system and additionally waste data storage - especially in huge archives.
ExactScan therefore comes with a sophisticated auto crop and de-skew algorithms that automatically try to detect page borders and skew. The pages are rotated accordingly and cropped to the original paper boundaries:
ExactScan's automatic crop and de-skew illustrated:
