How to Make a Scanned PDF Searchable with OCR

A scanner or phone camera app saves each page as a picture. The PDF looks like a document, but it contains no actual text, so you cannot search it, select a sentence or copy a figure out of it.

OCR (optical character recognition) fixes this. It reads the words in the page image and adds them as an invisible text layer behind the picture. The page looks exactly as it did, but now your PDF viewer can find and select the text.

PDF Utility's OCR PDF tool runs on our server because recognizing text needs more processing than a browser can comfortably do. The file is uploaded, processed and returned, and uploaded files are deleted from the server as soon as the result is sent.

1. Open OCR PDF and add your scanned PDF (up to 50 MB).
2. Choose the language the document is written in.
3. Keep 'Scanned pages only (recommended)' selected unless you need every page read again.
4. Select Make searchable and wait. OCR takes a few seconds per page, so a long document takes longer.
5. Download the searchable PDF.

Open the downloaded PDF in your browser or PDF viewer and press Ctrl+F (Cmd+F on a Mac). Search for a word you can see on the page. If it is found and highlighted, the text layer is in place. You can also drag across a sentence to select it and paste it into another app.

OCR accuracy depends mostly on the scan. A few habits make a big difference.

• Choose the correct language. English, Hindi, Spanish, French and German are supported, and the wrong language produces mistakes.
• Scan at 300 DPI or higher, with the page flat and well lit.
• Use high contrast: dark text on a plain light background works best.
• Expect more errors with handwriting, very small print, stamps over text and unusual fonts.
• Proofread anything important, such as names, amounts and dates.

Some PDFs mix scanned pages with pages that already contain real text. With 'Scanned pages only' the tool skips pages that already have selectable text and reads only the scanned ones, so good text is never replaced.

Choose 'All pages, replace existing text' only when copying text from your PDF gives wrong or garbled characters, for example after an earlier low-quality OCR. This reads every page again and replaces the existing text.

The page images are kept, so the document looks the same. Crooked pages may be straightened and sideways pages turned upright to improve recognition. The file is usually a little larger because of the added text layer; use Compress PDF afterwards if size matters.

If you want to edit the words rather than just search them, convert the scan with PDF to Word, which also uses OCR and gives you an editable document.