How to Make Scanned PDFs Searchable with OCR
📅 2025⏱ 5 min read
When you scan a physical document to PDF, the result is essentially a photograph of the page. The text looks readable to a human eye, but to a computer, it is just pixels — you cannot select text, search for words, or copy content. OCR (Optical Character Recognition) solves this by recognising the text in the image and embedding actual text data into the PDF.
OCR is the technology that analyses images of text and converts them into machine-readable characters. Modern OCR engines use machine learning models trained on millions of document samples to recognise characters with high accuracy. Our tool uses Tesseract.js — a WebAssembly port of the industry-standard Tesseract OCR engine — running directly in your browser.
OCR accuracy depends heavily on the quality of the scanned document. A clean, high-contrast black-and-white scan at 300 DPI typically achieves 95%+ accuracy. A crumpled, low-resolution scan of a handwritten document may only achieve 70-80%. For professional documents printed in a standard font at reasonable size, accuracy is generally excellent.
Our OCR tool supports over 100 languages including English, Spanish, French, German, Chinese, Japanese, Korean and Arabic. For documents with special characters, mathematical symbols or non-Latin scripts, selecting the correct language in the settings improves accuracy significantly.
Once OCR is complete, the resulting PDF contains a hidden text layer beneath the scanned image. You can search the document using Ctrl+F in any PDF viewer, select and copy text, and the document will be indexed by search engines if published online. You can also feed the OCR-processed PDF into our PDF to Word converter to get a fully editable document.