Earlier I addressed the allegations that Obama's birth certificate was a fake. Recently I revisited the site which had originally brought this question to my attention and I found another post on the same topic. And, while the newer post is also well reasoned, I think there is another issue I should mention.

In my first reply, I postulated that the halo, the lack of green between characters and the washing out of the watermark could all be accounted for by sharpening of an image, and that is still possible. However, I forgot one other possibility, which I raised in replying to this new post.

The image is stored in JPEG format. For those who do not know much about the minute details of computer graphics, they tend to think in terms of bitmaps, where each number represents a single pixel of the image*. JPEG does not work that way, it is what is called lossy. That means that, instead of encoding each pixel, a code is developed for a block of four or nine or sixteen or more pixels, and that code used to represent that block. The size of the encrypted block can be controlled by the encoding software. Taking it down to block size of one gives an encryption algorithm that is effectively the same as a bitmap, anything higher results in some loss of picture quality.

The size of the resulting file can also be controlled by limiting the total number of possible blocks. By using a large number of different blocks, something approaching bit map quality can be achieved. Using a smaller number of possible blocks results in more homogeneous images, as the image must be represented in many places with only an approximation of the actual image. So, in order to get a true bitmap, not only does the JPEG need to use 1 block per pixel, but must allow enough possible blocks to represent every color in the original image.

On the web images are often encoded in relatively low quality JPEG format (that is, a format using very large numbers of pixels per block, along with a small pool of possible blocks), so that a large picture can be stored in under 100 KB. This allows the quick loading of images over network connections, but it does result in slightly distorted pictures.

And that is why a pixel-by-pixel analysis of Obama's birth certificate may be pointless. If it was scanned and then stored as a relatively low quality JPEG, the distortion can be quite high, and things which look like outright forgeries can be simply the result of the encryption used.

All of which brings me back to my original point. I simply cannot believe that Obama is ineligible to hold office. Even if he does have a forged birth certificate, would it be possible for someone ineligible to hold office to hide that long enough to be sworn in? It would mean that everyone who had access to the Hawaiian records, as well as everyone at the real place of his birth, would have to be in on the conspiracy. That simply boggles the mind.

----------------------------------------------------

* I am hardly an expert in this area, as the slightly jumbled description I gave attests. I have worked on some graphics-related software, but mostly for fax firmware and related software. I wrote code to convert CIELAB to RGB, for example, but did not do much programming related to JPEG format, as most of my work was in various forms of TIFF format. So, while I understand how JPEG works, I am hardly an expert.

----------------------------------------------------

UPDATE

I have not read every post on Polarik's site, and I may have missed a discussion of this very topic. If so, I apologize and I would be happy to acknowledge any explanations I failed to consider. However, I think that, while the image was initially suspicious, upon more reflection it simply does not make sense that Obama would be running were he ineligible.

I confess that early on I thought that some claims did suggest a forgery, and I postulated that, while eligible to run, Obama did not have a certificate in his possession, and either the DailyKos or his campaign mocked up a certificate, which inadvertently ended up posted on one site and copied by the other, resulting in a forgery where none was necessary. However, having thought more, as I explain above, I think that almost everything that is seen in the image can be explained by the way data is encrypted, possibly increased through efforts to sharpen the image.

But, as I said, I have not read all of Polarik's posts on this topic, so I shall be reviewing those as time allows, and may be modifying my position should other posts cause me to rethink my objections.

NOTE: I do not single out Polarik's site out of any animosity. I actually picked his site bacause it seemed the best representative of the argument I could find. I am rather impressed with all the work he has put into it. Just wanted to make that clear.