Someone else has already...but NRO has, I think, effectively put this issue to rest.
http://www.nationalreview.com/corner/265767/pdf-layers-obamas-birth-certificate-nathan-goulding
http://www.nationalreview.com/corner/265767/pdf-layers-obamas-birth-certificate-nathan-goulding
A comment from the NRO article:
joefriday "I'm not going to say that the information on the document is bogus, but I can definitely, without hesitation, say that the document was originally a two-layer piece.
The top layer is the 'black' part that came from a scanner as a grayscale scan. It was converted to black and white and the white part was made transparent.
That was dropped onto of a generic green watermark background, which is what makes it look official. But that was NOT on the original document as scanned. This is very evident by the white haloing around everything black.
It is also extremely evident that a layer was dropped onto the green background because the green marks are very crisp in the areas around the edges of the image, but are very blurred where the black image block covers it.
Now keep in mind that before the green background was added, the original scan could have easily been altered.. dates or names changed. I'm not saying it was. I'm just saying it's a 100% fact that it could have been.
So, this document as we see it is still not proof of anything. I could easily recreate this document with someone else's original Hawaii birth certificate and a generic watermark background."
So Trump, Now What?
The layering issue was the only plausible doubt I had about the document, but figured there was an explanation. Thanks for the link with that explanation.