Layers are produced by a digital reprographc process known as Mixed Raster Content (MRC) so the PDF of a document can have layers.
Actual photographs of the hard copy of Obama’s birth certificate which were taken at the press conference for the Washingtn Press Corps on April 27, 2011 have no layers.
J. Scott Applewhite, a photographer for the Associated Press took this photo of the hard copy of the Obama Certificate of Live Birth.
http://www.syracuse.com/news/index.ssf/2011/04/white_house_releases_obama_bir.html
B$. The document posted on the internet by the Obama administration is a fraud, period.