crop scanned pdf pages

Flatbed scanners and phone scanning apps both commonly capture slightly more than the document itself: a dark border from the scanner lid, a sliver of the surface underneath, or simply extra margin because the capture area was set larger than the actual page. None of this is part of the real document content, and cropping it away cleans up the final result noticeably.

Since scanning artifacts like this tend to appear consistently around the edge of every page in a batch (the same scanner, the same setup, scan after scan), a single uniform crop applied to the whole document usually works well here, more reliably than for documents where content position varies page to page.

Start with a moderate crop and check the preview closely at the edges specifically, since scanning artifacts are often just a thin strip, a few percent of the page, rather than a large margin. Over-cropping risks cutting into the actual scanned content, while under-cropping leaves visible scanner artifacts in the final file.

If your scans include documents of genuinely different sizes or orientations in the same batch, a uniform crop is less reliable, since the artifact position and size can shift depending on how each original page was placed on the scanner. In that case, consider processing groups of similarly-scanned pages separately rather than trying to find one crop value that works for every page.