Making a non-searchable PDF searchable

If Ctrl-F finds nothing in a PDF, it is almost certainly a scan — a picture of text with no text underneath. OCR fixes that.

Why search fails

Search looks for text objects. A scanned page has none — just an image — so there is nothing to match.

Add a text layer

OCR recognises the words in the image and stores them as an invisible text layer, so search and copy start working while the page looks unchanged.

Language matters

Pick the right recognition language for accuracy, especially for accented or non-Latin scripts.