Docu Stop
If you have ever tried to select text in a scanned PDF and ended up highlighting the whole page like an image, you have met the core limitation of a scan: to a computer, it is a picture, not a document. You cannot search it, copy a sentence from it, or read it aloud with a screen reader.
OCR — optical character recognition — fixes that. It reads the shapes on the page and rebuilds the text layer underneath, so your scan becomes a genuinely searchable document without losing its original appearance.
Key takeaways
- A scan without OCR is an image; OCR adds the searchable text layer underneath.
- Test for a text layer by trying to select or search before you bother running OCR.
- Scan at 300 DPI or more and straighten pages for the best accuracy.
- A searchable scan is a prerequisite for translation, summarising and accessibility.
What OCR actually does
OCR analyses each page, recognises characters, words and their positions, and adds an invisible text layer on top of the original image. The page still looks exactly like your scan — but now you can search it, copy from it, and index it.
You have probably benefited from OCR without realising it. When you search inside a decades-old scanned report or a scanned book, you are searching a text layer that OCR created.
When a scan needs OCR
Not every PDF needs it. A quick test: try to select a word with your cursor, or press Ctrl+F (Cmd+F on a Mac) and search for a word you can see on the page.
- If text selects normally and the search finds words, the PDF already has a text layer.
- If selecting highlights the whole page and search finds nothing, you have an image-only scan and OCR will help.
- If search finds some words but not others, the file is partially recognised and re-running OCR can improve it.
How to OCR a document
In the Docu Stop app, OCR is built in:
- Open the OCR tool and import your scanned PDF or a photo of a document.
- Let the app detect the language, or set it manually for best accuracy.
- Run recognition — the tool returns a searchable document with the text layer added.
- Open the result, search for a word, and confirm the text layer is working.
- For just a few pages, the free Extract Text web tool can pull the words out as plain text instead.
How to get the most accurate OCR
The quality of OCR output depends far more on the input than on the software. A few minutes spent improving the scan pays off:
- Scan at 300 DPI or higher — low-resolution images are the single biggest cause of errors.
- Keep pages straight. A few degrees of skew confuses recognition, so use Rotate PDF to straighten them first.
- Prefer even lighting over harsh shadows when photographing a page with your phone.
- Keep the page flat and avoid curl near the spine of a book.
- Match the language setting to the document; mixed-language pages are harder for any OCR engine.
OCR is not just for search
Once a document has a text layer, a whole set of follow-on tasks becomes possible. You can translate it, run an AI summary over it, feed it into a spreadsheet, or make it accessible to screen readers. Many accessibility and records-management rules effectively require documents to be searchable rather than image-only.
In other words, OCR is often the step that unlocks everything else you want to do with a scanned document.
Frequently asked questions
Does OCR change how my PDF looks?
No. The original page image stays in place. OCR adds an invisible text layer on top, so the document looks identical but becomes searchable and copyable.
Why is OCR sometimes in the app only?
OCR is computationally heavy, especially on long, multi-page scans. The Docu Stop app can process large files reliably, while the free Extract Text web tool is best for pulling text out of smaller, text-based PDFs.
Can OCR read handwriting?
OCR is strongest with printed text. Handwriting is much harder and only reliably recognised when it is very neat, so treat handwritten notes as a bonus rather than a guarantee.
Does OCR work in other languages?
Yes. Docu Stop supports multiple languages, and accuracy improves when you set the correct language rather than leaving detection to guess.
Tools mentioned in this guide
Related guides
CompressionHow to compress a PDF without losing quality
Why PDFs balloon in size, what a compressor really changes inside the file, and how to get under an email limit without turning crisp text into a grey smudge.
7 min readRead guide
OrganisingHow to merge PDF files into one document
Combine contracts, scans and reports into one clean file — and learn how to order pages, drop the parts you do not need, and keep the result easy to navigate.
6 min readRead guide
SecurityHow to remove a PDF password you already know
Unlocking a PDF you own is a normal maintenance task, not a hack. Here is what removing a password changes and how to do it responsibly.
5 min readRead guideTry these tools in your browser
Docu Stop runs the core PDF and image tools for free — no sign-up, no watermark, nothing to install.