First, while we don't know how that PDF was produced, whether you use a scanner directly or use PSE or use Acrobat, or etc, the algorithm to produce a PDF is a documented standard - read it for yourself. In reading that standard there is NO discussion whatsoever or using a "dictionary of shapes" to save space. That just doesn't seem to be there. So, the contention that the identical boxes is due to a compression artifact is wrong from a theoretical perspective in the first place.

Third, attacking me personally because I am not a document expert is just a way of avoiding actually arguing the point. I have yet to see one of you either post another document with the anomaly or explain why my position is wrong.

Is this uncommon?

The big question is: why use a bitmask to add black to the image, instead of just rendering the image with black? The answer is: I hate PDF documents. There are an infinite number of ways to store an image in a PDF document, and the PDF encoding system used to create the PDF decided to use this method. This isn't even odd or abnormal. It is strictly dependent on the encoding system and encoding parameters. Even choices like "apply color profile", "optimize for printer", "use this paper size", and "export as PDF" vs "Save as PDF" can seriously tweak how the final PDF is generated; it usually isn't as simple as scaling or recoloring.

Another question that I expect to be asked: Why aren't all of the letters in the masks? The masks are only monochrome and act like a stencil. A single color is applied based on the masked regions. The fact that some letters are not in the masks shows that the images were scanned in and not everything dark is actually black. There is a significant amount of black, suggesting color correction or possibly OCR-based letter extraction during the scanning or conversion to PDF. I've seen this in other PDF documents, so this does not strike me as odd.

The PDF released by the White House shows no sign of digital manipulation or alterations. I see nothing that appears to be suspicious.

This is a really strange forum. All I did was ask if there was anyone here who could back up the claim that the identical check box anomaly was due to the presence of "compression artifacts" commonly found in the production of a PDF. Not a single one of you has posted anything which answers the question.

I'm sorry if you think I'm a "bozo" or "don't know jack", but at least I attempted to look into the matter. You are all clearly insufficiently cynical of what you read on the internet.

I think that this set of posts reinforces my observation - that the poster was operating with little or no knowledge of PDF's or digital image compression algorithms. I suggest that you try it for yourself and see if you can get a similar effect, I'd be interested in seeing it. Incidentally, 15 minutes more of looking at that PDF discloses identical large letters (bit for bit) as well.

Now you can all go back to patting each other on the back.

Rgrds

1. Yes.
2. "All I did was ask if..."???? Really? Actually, in your four posts so far, you have only asked a single question -- in your third post, where you wrote "I never said it was a fake, did I". In no other passage did you ever ask any other question, let alone the one you now invent. It is considered trollish behavior in this forum to misrepresent your own record. But maybe since you find this a 'strange' forum, it is normal and expected behavior in the forums you usually frequent.


See (1) above. On second thought, since you still haven't asked the question you say you previously asked (and did not ask) I withdraw my answer.


We are cynical about things that matter. And extremely cynical about trolls who lie in post 4 about what they wrote in posts 1-3.

Epectitus did an excellent logical report: http://www.thefogbow.com/special-report ... al-report/

If you still have questions after that, you are beyond help. And really, Photoshop Elements?

The "special report" just states that it's a compression artifact. It gives no technical reason why this is so and gives no example of it anyplace other than the PDF.

Thanks to Shoreditch for his post - could you tell me where the entire set of posts you mention can be found?
Rgrds

Thanks to Shoreditch for his post - could you tell me where the entire set of posts you mention can be found?
Rgrds

The "special report" just states that it's a compression artifact. It gives no technical reason why this is so and gives no example of it anyplace other than the PDF.

Nathan Goulding has a [link=http://www.nationalreview.com/corner/265767/pdf-layers-obamas-birth-certificate-nathan-goulding]great write-u[/link]p for making the Quartz PDFContext library generate a PDF with masks — just like those seen in this birth certificate. In his example, he is not doing anything fancy or special. He just selects one optimization setting.

Okayyyyy ...

This is a really strange forum. All I did was ask if there was anyone here who could back up the claim that the identical check box anomaly was due to the presence of "compression artifacts" commonly found in the production of a PDF. Not a single one of you has posted anything which answers the question.

I'm sorry if you think I'm a "bozo" or "don't know jack", but at least I attempted to look into the matter. You are all clearly insufficiently cynical of what you read on the internet. I think that this set of posts reinforces my observation - that the poster was operating with little or no knowledge of PDF's or digital image compression algorithms. I suggest that you try it for yourself and see if you can get a similar effect, I'd be interested in seeing it. Incidentally, 15 minutes more of looking at that PDF discloses identical large letters (bit for bit) as well.

Now you can all go back to patting each other on the back.

Rgrds

Who is Shoreditch? Wrong forum, Woody?

The technical reasons are quite simple: Text and Graphics compress differently. So the compression separates the background from the text and thus the background, which is highly repetitive because of the security paper, can be compressed using lossy jpeg, while the text is displayed as black and white only. There is a good example in the right '1' of the certificate number which failed to be recognized as text and is shown as a lossy jpeg, making it look different from the rest.
When seeing the high resolution copy, it is clear that this is a compression artifact.

Thorswitch. (Quoting from Neal Krawetz's post.)

Lack of reading comprehension is a bitch. (And an apparent reason for the new birther's "confusion"). Reminds me of an allegedly technical MichaelN.

I think I'm almost flattered. I've never had anyone try to mock me by mutilating my name before! What it's supposed to mean, I haven't got a clue (nor do I want one, quite frankly,)

TW - he can't read. I don't think it was intentional. I think it merely reflects a part of the problem he has.

Shoreditch is an area of London. In Hackney, I think, but I haven't lived in London for years so I might be wrong about that. Shakespeare used to live near there.

I was struck by the fact that the PDF released by Obama contained identical check boxes. It seems that one of your posters claims that this is a compression artifact. This made sense to me so I went back and looked a a number of old documents which I had previously scanned into my computer as uncompressed TIF's (color). I then tried to compress them into PDF format using Adobe Photoshop Elements. I could NOT generate any letter or box or number, etc which was identical to another in the document.

Actually I asked for 'comments and corrections' to my proposition in the first post if you bothered to read it.