If you’ve ever tried to copy text from a scanned PDF and ended up with nothing — or tried to search a document and got zero results — you’ve experienced the problem that OCR solves.
What Is OCR?
OCR stands for Optical Character Recognition. It’s the technology that reads text from images — whether that’s a photo of a page, a scanned document, or any PDF that was created from a scan rather than exported from a word processor.
When you scan a physical document, what you get is essentially a photograph of text. The computer has no idea those shapes are letters — it just sees pixels. OCR analyzes those pixel patterns and converts them into actual machine-readable characters.
Two Types of PDF
Searchable PDFs are created digitally — exported from Word, generated by accounting software, or produced by any application. The text in these PDFs is actual text: you can select it, copy it, and search it.
Image PDFs are created by scanning physical documents. They look like text but the content is just pixels. You cannot select, copy, or search the text without running OCR first.
When You Need OCR
You need OCR when: you’re working with scanned contracts, invoices, or letters; you need to make old paper records searchable; you want to extract data from scanned forms; or you received a PDF from someone who scanned rather than exported it.
How to OCR a PDF with PDFRun
PDFRun’s OCR tool processes your scanned PDF and returns a fully searchable version:
1. Go to pdfrun.io/tool/ocr
2. Upload your scanned PDF
3. Select the document language for best accuracy
4. Click Run Tool
5. Download the searchable PDF
The result is a PDF that looks identical to the original but now has a text layer — making every word searchable and selectable.
OCR Accuracy
Modern OCR is highly accurate for clear, well-scanned documents — typically 98–99% accuracy on standard print. Accuracy drops on handwritten text, very small fonts, poor scan quality, or documents with unusual layouts. For best results, scan at 300 DPI or higher.
PDFRun supports OCR in English, French, Spanish, German, Arabic, and Chinese, with auto-detect for when you’re unsure of the language.