It used to be that, if you hoped Google would index a PDF file, you had to create a PDF that was text-based, not image-based; Googlebot couldn’t recognize the content of scanned or image-based documents. According to an announcement today, that’s no longer the case.
Google says it’s now using OCR (Optical Character Recognition) technology to read any scanned documents that it finds in PDF format:
This Optical Character Recognition (OCR) technology lets us convert a picture (of a thousand words) into a thousand words — words that can be searched and indexed, so that these valuable documents are more easily found.
Google’s announcement includes a few examples where you can see the results of OCR scanning in action. On a search for repairing aluminum wiring, the first result is a Consumer Product Safety Commission PDF that was clearly scanned as an image. You can now get the text of that image thanks to Google’s OCR scanning and the “View as HTML” link on the search results page. As with any use of OCR, results are probably not going to be perfect. But the examples Google provides do look quite accurate.
Countless new documents are now available to searchers — documents that were never available before. On the other hand, if you’ve been scanning and uploading image-based PDFs knowing that they’d never be found by searchers — and I know people who have — you may want to rethink that strategy.