[photo-3d] Chromatic aberration / chromostereopsis

[boris@xxxxxxxxxxxx]

In a holmes viewer, because of the _prismatic_ element in the optics,
chromatic aberration is in opposite directions for the left and right
views.

So the left eye sees blue shifted to the right, and vice versa.

A large magnifier will do the same to a flat color picture, resulting in a
form of stereo that shifts colors to different planes.  That's because
light rays going to one eye will travel through a different part of the
lens (near the edge, where it works much like a prism) than the rays going
to the other eye.  (But for the large magnifier, red appears shifted up,
blue depressed).

Boris