Scanned PDF vs Normal PDF: How to Tell the Difference
Two PDFs can look exactly the same on screen and behave very differently. One lets you select, copy and search words. The other will not, no matter what you try. The difference is whether the PDF contains real text or only pictures of text.
The two types
Normal (text) PDF
Created by saving or exporting from a word processor, a spreadsheet, a website or an app. The words are stored as text. You can select them, copy them and search for them. These files are usually small.
Scanned (image) PDF
Created by a scanner or a phone scanning app. Every page is a photo. The words look like words to you, but to the computer they are only coloured dots. These files are often large.
Scanned PDF with hidden text
Some scans have been processed with OCR (text recognition), which adds an invisible layer of text on top of the picture. These files look scanned but can be searched and copied, although mistakes in the hidden text are common.
Four quick ways to check yours
- Try to select a word. Click and drag over some text. If it highlights word by word, the PDF has text. If a whole block or nothing highlights, it is probably a scan.
- Search the page. Press Ctrl + F, type a word that you can see on the page. No results usually means the page is an image.
- Look at the file size. A short text document is often only a few hundred KB. A scan of the same length can be several MB.
- Use the PDF to Text tool. If it says no text was found, your PDF is made of images.
Why it matters
- Copying and searching: only text PDFs (or scans with hidden text) support them.
- File size: scans are big, so they hit email limits sooner. See how to make a PDF smaller for email.
- Compression: shrinking a scan loses little, because it is already a picture. Shrinking a text PDF with the Strong method turns the text into pictures, so you lose the ability to select it.
- Accessibility: screen readers cannot read pictures of text.
What can you do with a scan?
- Make it smaller with Compress PDF.
- Convert pages to pictures with PDF to JPG or PDF to PNG.
- Use OCR if you need to copy the words. Many office apps and cloud services offer it. Results depend on the scan quality, and some services upload your file, so be careful with private documents.
Tips for better scans
- Use good, even light and keep the page flat.
- Scan at a clear resolution, but not higher than you need. Very high settings create huge files.
- Keep the text straight, and avoid shadows from your hand or phone.