How to Edit a Scanned PDF, and What OCR Can't Fix

How to tell if your PDF is a scan

Open the file and try to select a single word with your mouse. If the cursor changes and the word highlights, there is a text layer. If you can only drag a box around the whole page, or nothing happens, you are looking at an image.

Some scans are in between. A scanner or an earlier tool may already have added hidden text, sometimes badly, so that selecting a word highlights the wrong letters. Edit PDF notices when a page looks scanned and offers recognition, and you can run it from the toolbar yourself if a page looks wrong.

How to edit a scan step by step

1. Open Edit PDF and select the scanned file.
2. Click Recognize text (OCR) in the top toolbar.
3. Pick the language of the document. You can choose more than one for mixed pages, such as English and Hindi.
4. Choose a model, then wait. All of the work happens on your own computer, so a long document takes longer on an older machine.
5. Click a detected line and read it carefully, because recognition can misread letters.
6. Retype the line and press Enter. Repeat for any other changes.
7. Click Download and check every changed line in the new file.

Choosing an OCR model

If the AI model can't read your chosen language, the dialog tells you and uses Accurate instead. You can set text to be grouped by line or by word. Line mode is usually better for editing because you can retype a whole sentence in one go. Our test of OCR on real scans shows how resolution changes accuracy, so rescan at a higher setting if a page comes out garbled.

What happens to the original scan

This is the part most guides leave out. On a digital PDF, the editor deletes the old characters. A scan has no characters to delete, so it works differently. The editor paints a patch over the old words, using a colour sampled from the background, and draws your new text on top.

• The page will look right on a clean white scan. On a textured, shaded or stained background, the patch can be visible.
• The new text uses a clean digital font, so it can stand out against typewritten or handwritten pages.
• The original image is still in the file beneath the patch. Someone with the right tools could recover it.

When you should use a different route

If the goal is to find and copy text, leave the page alone. OCR PDF adds a hidden text layer behind the page image, so the scan keeps its exact look and becomes searchable.

When you need to rewrite most of a document, editing it line by line will take longer than retyping it. Turning the file into a Word document with PDF to Word gives you text that reflows, and it reads scanned pages automatically. Microsoft warns that PDFs of book chapters or manuscript-style scans won't format well in Word, so expect to tidy up the result.

Handwriting is the hardest case. These models are built mainly for printed text, so handwritten notes often come out wrong. Check every word, and consider adding a new text box beside the original rather than replacing it.

Why you can't copy text from a scan

If copy and paste does nothing, or pastes gibberish, the page has no usable text behind it. Your PDF reader only sees pixels, in the same way that it can't copy words out of a holiday photo. Running OCR fixes that. Once OCR PDF has added a text layer, you can search the file, copy from it and let a screen reader read it aloud. A few files do hold real text but block copying through a permissions setting, which is a separate problem, and OCR won't be needed for those.

Getting a better result from a scan

• Scan at 300 DPI when you can, because low resolution is the most common cause of misread letters.
• Lay the page flat. Curved lines near a book's spine are hard to read.
• Use the clean-up option in the OCR dialog when a page is dim or low in contrast.
• For phone photos, shoot in even daylight, square on to the page, and avoid shadows from your hands.

Frequently asked questions