How to prepare a scanned PDF for OCR

OCR cannot recover information that is missing from the scan. Preparing the source pages well can improve recognition quality before the document reaches the OCR engine.

Updated September 28, 2026 · FreePDF Tools

Straighten the pages

Pages that are sideways or strongly skewed make reading order harder. Rotate obviously misoriented pages before OCR when possible.

Prefer clear text and contrast

Clean black-on-white text at a sensible resolution is easier to recognize than tiny, blurred or heavily compressed text. Avoid repeatedly resizing a scan before OCR.

Watch tables and columns

Multi-column reports and dense tables are more difficult because OCR must first decide the reading order. Expect extra review work around numeric columns and merged cells.

Plan a manual review

OCR output is a recognition result, not a proof of the source. Check names, numbers, dates, punctuation and any value that affects a decision before using the editable file.