OCR and hidden text in PDF scans of historic documents

Question

I need to edit the hidden text behind a scanned PDF image of a document.  The image must remain as an “exact” copy of the original scanned document.
I used Acrobat Pro (versions 7 and 9) to make PDF images of old typed documents from the 1940’s.  When I open those images and run OCR in version 9, then examine the hidden (invisible) text layer behind the image, there are errors.  For example, the word “book” has been picked-up by the OCR as the word “look.”  I need to change the “l” to a “b” in order to make the PDF accurate when it is searched at a later date. 
I have checked many user forums.  Most people imply that hidden text can be viewed, but NOT edited in Acrobat Pro 7 and 9.  (Hidden text can be viewed in Version 9 by selecting “Document” “Examine Document” and then clicking on the “+” symbol next to “Hidden Text,” then clicking “Show preview.”)  Some say to use Adobe Capture 3.0 to edit hidden text.  Others say to use Photoshop or Illustrator to edit hidden text (I think these folks may have been confused, because Photoshop and Illustrator would be used, logically, to edit the image ON TOP OF the hidden text).  Yet another person seemed to say that a hidden text editor was added to Acrobat 8, but was taken away in Acrobat 9.  (I can’t verify that because I don’t have version 8.)
The closest answer I was able to find involved using the Text Touch Up Tool on top of the image to edit hidden text behind it, but when you do that you are typing “blind.”  In other words, you highlight a spot on the image (top layer) where you THINK the error MIGHT be, and you type the correction without being able to see what you are typing over.  Then, you go back to the “Examine Document” procedure (described above) to see if you “hit” your mark, and if not, you redo it until you do “hit” your mark.  With the number of documents and corrections that we have, that procedure would be too labor intensive and thus a budget breaker.
If we have to buy more software, my preference would be to buy a genuine Adobe product because I have experienced problems in the past switching back and forth between Adobe products and other PDF manipulation software.
Can anyone answer any of these questions: 
(1) Is there a way in Acrobat versions 7, 8 or 9 to edit hidden text, and if so, how? 
(2) What Adobe software (other than Acrobat) will edit hidden text behind a PDF image? 
(3) Assuming no Adobe product will edit hidden text behind a PDF image, is there any non-Adobe products that will do that?
Thank you!

Answer 1

Hi,
Unless you use Acrobat 8 Pro's Formatted Text & Graphics" or Acrobat 9 Pro's ClearScan you will find that there is no
practicable means of editing the OCR "hidden text" in a PDF.
The TouchUp text tool (Advanced Editing toolbar) is reliant upon the selected text having an available system font to use during touchup. However, both Searchable Image and Searchable Image (Exact)  OCR output is of text rendering mode 3 (invisible text) that is provided from within Acrobat and not any installed system or other application installed font.
With Searchable Image (Exact) you have the untouched image augmented by the invisible text which is provided as a user aid for search or find with Adobe Reader or Acrobat. The invisible text is not intended to support word processor like editing.
To your questions:
#1. There is no practicable way to edit invisible text (text rendering mode 3) with Acrobat (any past or current release).
#2. None.
#3. A good question. Perhaps a specialty program. Keep in mind, many products provide a promise but those those that actually deliver tend to be expensive.
Something to play with. Using Acrobat 9 Pro or Pro Extended, try the Preflight Fixup to embed hidden text.
Then try using the TouchUp Text tool. You may also want to see if you can change the font type of this newly embedded font.
(use copies of the "real" files - just in case <g>).
Be well...