Sabina Fata 

Good question. I think the real problem is related to the quality of the PDF itself as opposed to the resolution. So if your PDF is poor then the resolution won't help at all. I think if you are creating the PDF from a printed document for example ten go with the best resolution you can, unless there are so many pages that the size becomes unworkable. In this case probably split the file up. So quite a few variables when handling PDF files... no one size fits all approach I think.

Tagging Patrick Andrew Hartnett  who may have a view on this?

Sabina Fata 

Good question. I think the real problem is related to the quality of the PDF itself as opposed to the resolution. So if your PDF is poor then the resolution won't help at all. I think if you are creating the PDF from a printed document for example ten go with the best resolution you can, unless there are so many pages that the size becomes unworkable. In this case probably split the file up. So quite a few variables when handling PDF files... no one size fits all approach I think.

Tagging Patrick Andrew Hartnett  who may have a view on this?

Hi Sabina Fata ,

As Paul suugested, it depends and no one size fits all.  After reviewing various forums on the subject, there does seem to be a general opinion that for most documents, starting from 300 dpi is sufficient for good legibility and to provide adequate OCR results.