Two PDFs can look identical and behave completely differently. Knowing which kind you have explains most conversion failures before they happen.
Why did converting your PDF to Word produce an empty document? Why does Ctrl+F find nothing in a document full of text? Why is one three-page file bigger than a two-hundred-page one?
All three questions have the same answer, and it is the single most useful thing to understand about PDFs.
Two completely different things in one format
PDF is a container. What it contains varies enormously.
A digital PDF — exported from Word, generated by an invoicing system, printed to PDF from a browser — stores real text. Each character is recorded as a character, with a font and a coordinate. The page is a set of drawing instructions.
A scanned PDF contains a photograph of a page. There are no characters anywhere in the file, only pixels that happen to form shapes a human recognises as letters. To software, it is no more readable than a picture of a landscape.
On screen they can be indistinguishable. In every other respect they behave nothing alike.
How to tell in two seconds
Open the document and try to select a single word with your cursor.
- The word highlights, character by character → digital PDF
- A rectangle covering the whole page highlights, or nothing happens → scanned PDF
A second check: press Ctrl+F and search for a word you can clearly see on the page. If it is not found, there is no text layer.
What follows from this
Nearly every confusing PDF behaviour traces back to this distinction:
- Converting to Word produced nothing. There was no text to convert. The converter worked correctly on an empty input.
- The file is enormous for its page count. Images are hundreds of times heavier than text. See what makes PDFs large.
- Search finds nothing. There is nothing to search.
- Copying text is impossible. Same reason.
- Compression behaved unexpectedly. Scanned PDFs shrink dramatically under image recompression; digital ones barely move.
Turning one into the other
You can add a text layer to a scanned PDF with optical character recognition. OCR analyses the image, recognises the character shapes, and writes an invisible text layer positioned behind the picture.
The result — a searchable PDF — looks exactly like the original scan, signatures and coffee stains intact, but can be selected, copied and searched. Once a scan has been through OCR it behaves like a digital PDF for most purposes, including conversion to Word or Excel.
Our OCR PDF tool does this in your browser, in twelve languages, producing both a searchable PDF and a plain text file.
The practical workflow
If you have a scan and need the content:
- Run OCR first to add the text layer.
- Then use PDF to Word for prose, or PDF to Excel for tables — both will now find real text.
Skipping the first step is the single most common reason people conclude that PDF converters "do not work."
One hybrid case
Some PDFs contain both: a digitally generated document with a scanned signature page appended, or a form with typed fields over a scanned background. Selection works on some pages and not others. Running OCR over the whole document is harmless — pages that already have text simply gain a redundant layer — so when in doubt, OCR everything.
Pixellwork Editorial
Documents & Privacy
Published October 3, 2026