A scan is simply a picture of a document, therefore, before running the accessibility check on a scanned document you will need to check the document to make sure that the pdf reader is recognizing the text and not simply seeing one large picture.
First, open the scanned pdf in Acrobat Pro DC and click anywhere in the scan. If one large blue square is shown then Acrobat is not recognizing the text in the document. So next:
- From the toolbar on the right side of your screen choose Enhance Scans
- In the Enhance Scans toolbar at the top of your page select Recognize Text > In This File
- A new toolbar will open, choose the number of pages, the language and Recognize Text
When clicking anywhere in the document, now you should get a cursor at the location you selected instead of a large blue square. This means that text is being recognized and you can run the Accessibility check.
- Now, close the Enhance Scans toolbar
- Select Accessibility from Tools tab in the Protect & Standardize section (to put the tool on the shortcut toolbar choose Add)
- Choose Full Check from the Accessibility menu
- In the dialog box that opens select Start Checking
