How to make a scanned PDF searchable with OCR

1 min read·25 July 2026

A scanned PDF is essentially an image: you cannot select or search text in it. With OCR (Optical Character Recognition) you convert the scan into a searchable, selectable PDF — for free with PDFrust.

What is OCR?

OCR analyses the image of a scanned document and recognises letters, numbers, and punctuation. The result is a PDF with an invisible text layer on top of the image. You can then select, copy, search text and use Ctrl+F to search the PDF.

When do you need OCR?

If you have scanned a contract, invoice, letter, or form, it is always an image-PDF. Without OCR you cannot copy text from it, the PDF will not be found in document searches, and the file is much larger than necessary.

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OCR in PDFrust

Open the OCR tool on PDFrust. Upload the scanned PDF. Choose the language of the document (Dutch, English, etc.) — this significantly improves recognition accuracy. Click "Run OCR" and download the searchable PDF.

Scan quality matters

OCR works best with scans of at least 300 dpi (dots per inch), straight text lines, and sufficient contrast. A crooked scanned A4 with stains gives less accurate results. Use the rotate tool to straighten a crooked scan before the OCR step.