Decoding a Magic Eye image

[T._Sc...@adobeforums.com]

Magic Eye images contain two images (one for each eye) that create an illusion of 3dimensionality. They are coverd with a pattern that helps you overlapping them by squinting. Is there a way to recover the original hidden image (a greyscale image where white comes towards you and black goes away from you)? I've tried Ps's Difference Mode, here are the results:
<http://www.pixentral.com/show.php?picture=1RwVXelUAyoMyTb2DFKSZtcJ9Jqi1>

The hidden image on the left is a flat shape (Normal view on top, Difference blending mode applied to a copy of the layer and then moved horizontally until the shape appears). The one on the right is a 3d shape and you can go from front to back through the shape by moving the top layer from left to right (or right to left). I would like to have patternless image instead, that features all "layers" (not Ps Layers) of the 3d body as brightness levels (height map) similar to this:
<http://linuxgazette.net/104/misc/kapil/base.png>