Redaction Part Two: Something Else You Shouldn’t Do

Note: Acrobat 8 Pro and up offer true Redaction tools which permanently remove information from the datastream of the document. You no longer need to use the method listed here. Acrobat 8 Standard and up offer true, Metadata removal which can automatically detect covered up text and other problems.

See this Redaction Article for full details.

I’ve received several comments about my article on redaction advocating a different method of producing the redacted PDF.

Wouldn’t it be easier to just add mark-ups covering information and print it to the AdobePDF print driver instead of saving to a TIFF file?

Doesn’t this “flatten” the file eliminating information underneath giving the same results?

Let me state this clearly: No it doesn’t!

Read on to learn why . . .

Note: This article was written before Acrobat 8 shipped which includes built-in bullet-proof redaction tools.<\p>

Proper Redaction Technique

To refresh everyone’s memory, in my first article on redaction, I discussed this workflow:

  1. Open a PDF
  2. Make annotations on top of the document that are filled black
  3. Save to TIFF
  4. Reconvert to PDF

Proposed Shortcut (but don’t use it!)

Some folks take a shortcut and simply print the “redacted” PDF to the AdobePDF print driver.

printdriver.gif

Acrobat will produce a new PDF without markups. However, the information is still there underneath the boxes representing the markups.

Prove it Yourself

You can test this yourself! Here are three files you can use:

1-Original File without annotations | 2-File with Annotations | 3-File printed to AdobePDF print driver

  1. Open up the File Printed to the AdobePDF print driver (#3 above)
  2. Go to Tools–>Advanced Editing–>Touchup Object Tool
  3. Click on one of the “redacted” objects and hold down the mouse to move it
  4. Aha! There’s the data!
not-redacted.gif

Notes, Complications and a Not Very Good Workaround

In my research, I’ve discovered a few tidbits that you might find helpful.

If you want to print annotations, you must go to Edit–>Preferences–>Commenting and enable “Print Notes and Pop-ups”

The AdobePDF print driver offers a “Print as Image” option. This does a decent job of emulating the results you would get from saving to TIFF. To try this yourself, go to Print and click the Advanced button at the bottom of the Print Window.

print-as-image.gif

An issue that I have identified with this workflow is that the resulting PDFs are greyscale and pretty big (about 80K a page).

For some reason, certain PDFs can’t be printed with annotations showing unless Print as Image is selected. I believe that the application used to create the original PDF (which many not always be from Adobe) has a bearing on this, but more testing is required.

Summing it Up

Improper redaction can lead to censure and malpractice . . . take this subject very seriously!

As mentioned in my last article, the best way to redact PDFs is to use a redaction plug-in from Appligent such as Redax or Redax Lite.

Remember, just because data isn’t immediately visible in a PDF, doesn’t mean it isn’t there. Taking shortcuts to save a bit on buying a plug-in for Acrobat isn’t worth it.