If you’ve scanned documents to PDF format, they may need to be OCR'd (Optical Character Recognition) in order to be readable. A scan may produce a PDF that is actually an image that contains text that is not readable.
We have a product called Snapverter that is used for converting files to be accessible. A trial version of Snapverter is available here.
(Note: Some publishers secure their content where they may not be allowed to be converted. In this case you will have to contact the publisher to see if they have an accessible version of the publication)
For more information about getting the best OCR results, please click here.