PDF OCR

A scanned PDF may look like a normal document while each page is actually an image. In that situation, selecting or copying the words may not work because the characters are not stored as ordinary PDF text.

Optical character recognition, or OCR, examines the rendered page and attempts to identify characters so that usable text can be produced from the scan.

Clear, straight, high-resolution pages with readable type generally give OCR a better starting point. Blur, shadows, handwriting, decorative fonts, low contrast, compression artifacts, skew, and complicated layouts can make recognition harder.

OCR should therefore be treated as recognition rather than a guaranteed transcription of every character.

The tool can produce different output types depending on what you want to do with the recognized content. A text-oriented result can be useful when you mainly need the words, while document output may be more convenient for further editing.

Changing the output format does not make recognition more accurate. The recognized text should still be checked against the source when accuracy matters.

If pages are noticeably tilted or difficult to read, correcting the scan before OCR can provide a cleaner source for recognition. Enhancement can also help some low-contrast scanned material.

These operations cannot recreate information that was never captured clearly in the original scan, so severely blurred or missing characters may still require manual correction.

Common OCR errors include confusing similar-looking letters and numbers, losing punctuation, misreading columns, or joining text in the wrong order.

Check names, account references, dates, totals, addresses, technical values, and other important details against the original PDF before using recognized text elsewhere.