Trying to OCR pdf, pdf says it can't perform bc it already contains renderable text-but does not.

Question

I work for a large agency, and we receive PDF's all the time. 98% of the time I am able to OCR a document with no issues. Just recently I have come across this issue several times, and was wondering if anyone can solve this irritating problem!
*Acrobat 8.1 - When going to OCR the document, I receive the following message " Acrobat could not perform recognition (OCR) on this page because this page already contains renderable text. However, it does not. When you go to select text or search for anything the whole page is selected (like it's still in a "picture" format, not a document format that you can search, ect.)
I am not sure if it is how the document is uploaded originally by the other party that causes this, but the only thing I can do as a work-around - is to print out the entire document, scan and then I can OCR the document just fine! The problem is, if the document is 400 pages or so, this can be a huge waste of time, and money just to be able to search the PDF.
*I have also checked the pdf properties to see if this is some sort of permissions issue, and there are not permissions/security settings in place.*
PLEASE HELP! Any assistance in this matter would save me a lot of time, and of course (my sanity!).
Thank you in advance!

Answer 1

While the alert speaks to "renderable text" that is a simplification. The issue is that you've PDF page content consisting of at least one renderable "character".
Look at font families - you will observe that there are many characters that are not "text" characters (i.e., linguistic characters).
So, there's a "renderable character" present. It may be an alpha numeric that has a font color the same as the page background. It may be under the image and thus not visible to the eye.
You might be able to determine just what is present.
You could export the page of interest to a text file then view that file.
You could deplay the page of interest in Acrobat Pro then select the "Content panel" to view the content tree.
Locate and click on the page number for the page of interest.
From the Content panel's Options menu select "Highlight Content".
Walk down the tree. Select the content containers in turn and observe what is highlighted on the PDF page.
Where might the renderable character come from ? Typically that'd be associated with something in the work flow.
Not always easy to find so don't take anything in the work flow for granted.
Be well...