How to Use OCR to Extract Text From Scanned PDFs
However clean a scan looks, it's just a photograph as far as a computer's concerned — no real text at all. OCR is what reads the shapes on that image and turns them into actual, searchable, selectable text.
Why accuracy swings so much
It comes down to scan quality. A clean, high-contrast scan of a typed page can hit 99%+ accuracy. A blurry photo of handwriting, faded ink, or a low-res fax can drop that dramatically — sometimes to the point of needing heavy manual correction.
Getting a better source scan
300 DPI minimum for text documents, good even lighting, no angled shots. Scanning with a phone instead of a real scanner? Use auto-crop and auto-straighten to cut down on distortion before OCR runs.
What good OCR actually gives you
Not just raw text — a searchable PDF that looks identical to the original scan but has an invisible text layer underneath, so you can search, copy, and highlight while the page still looks like a scan.
Multiple languages
Most OCR engines need to know the language to recognize characters accurately, especially non-Latin scripts. Mixed-language document? Check whether your tool supports multi-language detection — forcing one language on a mixed document gives you garbage in the wrong sections.
Always proofread after
Even good OCR trips over numbers — a '0' and an 'O', a '1' and an 'l' look alike. Proofread anything that matters: figures, dates, names. Don't trust it blindly.
