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Initial post: Jul 5, 2011 9:37:20 AM PDT
I read through Zebest's "analysis" of the long-form PDF file at http://www.wnd.com/files/Obama_LFBC_Report_final_draft.pdf. I will prepare a longer refutation in the coming days, but I will quickly note here why her analysis is so flawed as to be utterly useless.

It appears that Zebest has some experience with Illustrator and Photoshop, but none at all with Acrobat. She commits a very basic error throughout her document - she seems to be completely unaware that the White House copy of Obama's birth certificate is a compressed image. Why is this important? Because nearly all of her "suspicions" are easily explained as compression artifacts.

A real quick background on PDF compression - there are two main compression schemes in use here: JPEG and JBIG. JPEG is a compression scheme for color images that utilizes combinations of LZW (Lempel Ziv Welch), frequency analysis and DCT (Discrete Cosine Transform) to achieve impressively high compression. The JPEG compression scheme is lossy - meaning that some information will be sacrificed in order to achieve higher compression ratios.

JBIG is a compression scheme designed for bi-level (monochrome) images. It makes use of image segmentation, meaning that it can apply different compression algorithms to different parts of the image.

The exact routes followed by the image compressor very from vendor to vendor. This particular PDF was apparently created on a Mac using software not written by Adobe. Since the encoder algorithms are proprietary information, we can only talk about the compression process in general terms.

The first step is to separate the color components of the image from the monochrome components. Obviously, the green background will form most of this layer. However, it appears that some of the text was also assigned to this layer - probably due to the fact that the text color tends to vary throughout the document. The lighter elements (such as the 'R' in Barack) were recognized as color and assigned to the bottom layer.

The monochrome layer is then further split into constituent elements. The encoder will attempt to separate text, line art and general raster (bitmap) data from the image. Again, we don't have access to the compression algorithm, so we cannot say for sure how the separation was done.

The separated images are then subjected to a pattern matching algorithm that attempts to find duplicates. The reason behind this is that it is far more efficient to represent several images using one symbol. The exact threshold at which the encoder decides that two sub-images are the same is unknown.

When we look at all of these elements together, we can make a few guesses about what sort of artifacts we would expect in the PDF. First, we note that it is quite possible that parts of the text may be represented by different encoding schemes. In figure 5, for example, Zebest points out that the '4' and the '1' in the serial number appear to be different. Zebest is here comparing apples and oranges - the '1' was assigned to the color layer, and is encoded using a multi-bit color mapping, while the '4' was compressed with JBIG, and is thus monochrome. The 'noise' that Zebest is talking about exists only in her mind.

We would also expect that some symbols would be repeated. In figure 6, she notes that the 'i' is identical despite appearing in two different places. As we have seen, this is due to the compression algorithm deciding that they are similar enough to represent with the same symbol. This phenomenon occurs quite frequently in the compressed image - even the '1st' and '2nd' checkboxes in section 4 of the document were replaced with the same symbol, but the '3rd' was not. This strongly indicates that the duplicate detection was done via software rather than a human agency.

In short, by being ignorant of the manner in which image compression works in PDFs, Zebest's analysis is completely useless. Most of her points are irrelevant, and thus the "forgery" accusation remains unproven.

Posted on Jul 5, 2011 9:44:25 AM PDT
[Deleted by Amazon on Aug 18, 2012 1:33:32 PM PDT]

In reply to an earlier post on Jul 5, 2011 9:48:23 AM PDT
Dalekmaster says:
"In short, by being ignorant of the manner in which image compression works in PDFs, Zebest's analysis is completely useless. Most of her points are irrelevant, and thus the 'forgery' accusation remains unproven."

You mean she doesn't know what she's talking about? I'm shocked, shocked!

In reply to an earlier post on Jul 5, 2011 10:10:52 AM PDT
Last edited by the author on Jul 5, 2011 4:44:25 PM PDT
J. Potter says:
She's been an active birther since 2008, not at all an objective source, and neither is her report. She begins with a conclusion, and her "report" proceeds to conjecture on how one might go about creating / imitating such an image in Photoshop. Kinda like one of the how-to books she co-edited. This isn't a question of "how to" ... how the image could have been created ... but rather "what was" ... what does the information in the file indicate happened?

Entire sections aren't even relevant, seem to be thrown in as filler, such as the discussion of rich black. There are no instances of black or rich black in the PDF, only various shades of green grey, created by some text enhancement that created an average color from the grey of the lettering and the green security pattern. This makes me think, again, her report is closer to an art criticism, and is a "how to" piece, not at all a "forensic analysis". She seems looking at the image and speculating, not delving into the technical details of the PDF file, its objects, and their visual rendering.

Another of her speculations that comes to mind: sharpening. Could it be sharpening? In a word, no. The white halo is blended into the green background, exactly the opposite of what sharpening does. Also, the bitmap text is an entirely separate object from the halo. It wasn't created by sharpening, but by reduction to bitmap through an arbitrary rule, not a 50/50 pass, as the letters became heavier judging from other images. The process was biased more toward positive, rather than negative, like 60/40 or 70/30, as if to emphasize the text ... as in an arbitrary text enhancement.

Go, Curt, go. She makes it easy enough for you. Another in a chain of older, self-styled experts, offering tangential and/or outdated experience.

In reply to an earlier post on Jul 6, 2011 12:57:41 AM PDT
[Deleted by the author on Jul 6, 2011 7:52:26 AM PDT]

In reply to an earlier post on Jul 6, 2011 1:04:52 AM PDT
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In reply to an earlier post on Jul 6, 2011 4:16:28 AM PDT
Dalekmaster says:
"Here are Zebest's Publications."

Have you actually looked at that list? YOU'RE the one touting her as an authority on PDF files, but Acrobat isn't listed anywhere. And since people who really do know something about PDF files say she's full of it, I think we know why.

I love it when birthers manage to debunk themselves. It makes my life so much easier.

In reply to an earlier post on Jul 6, 2011 4:27:40 AM PDT
"Have you been published on Acrobat Curt?"

No. But then - neither has Zebest.

Posted on Jul 6, 2011 5:05:20 AM PDT
Brian Curtis says:
Thanks, Mark, for illustrating that Zebest is NOT, in fact, an expert on PDFs and Acrobat.

In reply to an earlier post on Jul 6, 2011 7:01:54 AM PDT
"Here are Zebest's Publications."

And here are the only publications that matter:

PDF reference: http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/PDF32000_2008.pdf

JBIG2 reference: http://www.jpeg.org/public/fcd14492.pdf

If I have erred, feel free to point out where.

In reply to an earlier post on Jul 6, 2011 7:52:05 AM PDT
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In reply to an earlier post on Jul 6, 2011 7:53:09 AM PDT
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In reply to an earlier post on Jul 6, 2011 7:55:12 AM PDT
Dalekmaster says:
"Still an Adobe expert which is more than we can so for most who have been posting on Amazon."

Photoshop, Acrobat - they're all the same anyway, right?

In reply to an earlier post on Jul 6, 2011 8:03:30 AM PDT
C. Gonzales says:
Photoshop has nothing to do with PDF files. That's like asking a mechanic for their expertise in dealing with heart surgery.

In reply to an earlier post on Jul 6, 2011 8:04:29 AM PDT
C. Gonzales says:
"Adobe expert" Sorry no dice pdf has been an open format since 2008, Adobe no longer has exclusive rights to it.

In reply to an earlier post on Jul 6, 2011 8:18:13 AM PDT
Instead of babbling about "experts", why not simply read the specs and point out where my analysis is incorrect? It's really not that difficult.

In reply to an earlier post on Jul 6, 2011 9:43:31 AM PDT
Does Photoshop even read PDF files? I seem to remember you need to change them to bitmap or jpeg. Too lazy to look up on my own especially when their are people on hear who actually understand the standards it works under.

In reply to an earlier post on Jul 6, 2011 10:29:26 AM PDT
Arus says:
Yes photoshp can open and read PDF's. If its a several page PDF, then it asks you what page you want to open. Sometimes, you want to edit the images embededded within a PDF in case you don't have the original source image that was used to make hte document and need to make a quick update.

Photoshop can save out to PDF (its Known as the Photoshop PDF format) which is a whole different set of algorithms and settings treated by the PDF creation engine in Photoshop that Acrobat Professional then can read into it's own program.

In reply to an earlier post on Jul 6, 2011 6:20:58 PM PDT
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Posted on Jul 6, 2011 6:22:57 PM PDT
Karl Denninger's Response to Curt's post:

Image compression explains some things but not all. It would make sense except that:

1. If the document was an actual scan (and not a computer-generated composite) then the entire image would be considered by the program. That would leave chroma information in the compressed border areas. It's not present. It *is* present in the AP copy (which is, in fact, a scan and not a computer composite.)

2. Common compression algorithms have a relatively small "lookback window." That is, while they look for identical elements to compress and then tag (saving the duplication) they have no way to display intelligence.

3. The layering differences in places such as the numeric stamp I've already gone through. They're not inconsistent with what is being described below. The problem, once again, is **on balance** the elements that got "randomly" assigned into various layers appear to display *intelligence*, and computer programs lack that. I've created dozens of PDFs from "safety paper printed" source materials trying to reproduce this sort of artifact chain and have failed repeatedly in doing so. National Review also tried to refute my arguments in this manner (along with those of others) and not only failed to refute my argument *they made my argument* as the layering displayed in their document was consistent with computer-generated decisions - while that in the Obama PDF is not.

4. Compression artifacts (which are a real phenomena) have nothing to do with the typography issues such as the perspective problems (the varying bend radius of text that should be on a constant radius given where it is and the "book" scan) and text alignment.

5. How is it that AP has a document that has no security paper background (and published it) but the allegedly same document on the White House site does - not only is the pattern different but so is the color! I thought there was one document - not two? ;-)

The other problem is the apparent obscene level of compression that was used - it IS extreme. These are nowhere near default settings - in fact, even with a lot of work I couldn't reproduce what was done in Acrobat in attempting to manipulate a scanned image using "ordinary production processes", and I put quite a bit of effort into it. If there's no intent to deceive then there wouldn't have been ANY effort put into this - they would have simply scanned the document, applied optimization (maybe) and published it.

-- Karl

In reply to an earlier post on Jul 6, 2011 6:25:31 PM PDT
C. Gonzales says:
Her word isn't accepted because she already made a determination years ago that the long form was "fake" before she ever saw it. She then fitted her data around that belief. It's a negative premise and shows she lacks the qualifications. She's not a forensic document examiner nor a professional. She veers off on subjects that are unrelated to her supposed expertise like say negro/african.

In reply to an earlier post on Jul 6, 2011 6:26:23 PM PDT
C. Gonzales says:
What are denninger's qualifications again? He ran an internet company?

In reply to an earlier post on Jul 6, 2011 6:27:52 PM PDT
C. Gonzales says:
The AP document has no security background? Is denninger serious? There's a reason why it doesn't show up. The security paper isn't meant to be photocopied. What the press got were photocopies compared to the copy that Obama showed.

Posted on Jul 6, 2011 6:40:10 PM PDT
J. Comer says:
"Here are Zebest's Publications.

Bouton, G., Zebest, M. (Contributing Author). (2000). Inside Adobe Photoshop 6. Indianapolis. New Riders Publishing.
Bouton, G., Zebest, M. (2001). Inside Adobe Photoshop 6 Limited Edition. Indianapolis: New Riders Publishing.
Stanley, R. (2001). The Complete Idiot's Guide to Adobe Photoshop 6. Indianapolis: Que Publishing. (Contributor Graphics).
Bouton, G., Zebest, M. (2002). Inside Photoshop 7. (Zebest, M., Tech. Ed.) Indianapolis: New Rider Publishing.
Huss,D., Zebest, M. (2002). Photoshop Elements 2.0: 50 Ways to Create Cool Pictures. Indianapolis: New Riders Publishing.
Bouton, G., Zebest, M. (2004). Inside Photoshop CS. (Zebest, M., Tech. Ed.) Indianapolis: Sams Publishing.
Giordan, D. (2005). How to Use Adobe Photoshop CS2. (Zebest, M., Tech. Ed.) Indianapolis: Sams Publishing.
Giordan, D. (2005). The Art of Photoshop: CS2 Edition. (Zebest, M., Tech. Ed.) Indianapolis: Sams Publishing.
Bouton, G. (2008). Adobe Photoshop CS3 Extended Retouching Motion Pictures. (Zebest, M., Tech. Ed.) Boston: Cengage Technology,
Cengage Learning.
Jenkins, S. (2009). How to Do Everything Adobe Illustrator CS4. (Zebest, M., Tech. Ed.) McGraw-Hill.
Grey, T., Burian, P. (2007). Photoshop Elements 5 Workflow: The Digital Photographer's Guide. (Zebest, M., Tech. Ed.) Indianapolis: Wiley
(Sybex) Publishing.
Bouton, G. (2010). Xara Xtreme 5 The Official Guide. (Zebest, M., Tech. Ed.) McGraw-Hill.

Have you been published on Acrobat Curt?

You state that most of her points are irrelevant, which ones are relevant Curt? "

Good info Mark. One would wonder why the Village MMer's don't want folks to see that.

In reply to an earlier post on Jul 6, 2011 6:46:58 PM PDT
C. Gonzales says:
She has no experience in PDFs and no experience as a forensic document examiner. She made a predetermination before Obama even released the long form. She's been a birther since 2008. So yeah she's just another birther flavor of the week like Vogt and Irey and pollarik and techdude another unqualified person.
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Initial post:  Jul 5, 2011
Latest post:  Jul 23, 2012

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Where's the Birth Certificate?: The Case that Barack Obama is not Eligible to be President
Where's the Birth Certificate?: The Case that Barack Obama is not Eligible to be President by Jerome R. Corsi (Hardcover - 2011)
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