ANAGLYPHS 169glyphs to their normal stereo form has often been raised, This is
very simple. The anaglyph is copied upon panchromatic film
using photographic filters which will separate the two ink colors.
When the same copy is used with both a tricolor A and a tri-
color C filter, the A filter will record the blue printed image and
the C filter will record the red printed one.
If the anaglyphs are of the polarization type, the camera filter is
a simple polarizing filter. One copy is made with the filter blank-
ing one image and the next exposure is made with the filter ro-
tated through go'. Panchromatic film is not necessary in making
polarization anaglyphic restorations.
Polarization Anag1yphs.-This is the process which is known as
the Vectograph and for some reason it has never been freely of-
fered to the amateur. The Vectograph process was developed by
the Polaroid Corporation and was widely used in World War 11
with the utmost success. It was later adapted to a unit for home use
for ophthalmic therapy by Bausch &: Lomb, and has had limited
use among amateurs. It is highly satisfactory in every respect and
solves many problems as old as stereo. The pictures are in full
tone, monochromatic (color is being developed) and have all of
the quality of a normal print. They exhibit the unmistakable
relief found in normal stereograms and, in fact, offer a solution
to the problem of an album full of stereograms which are to be
looked at in exactly the same manner as any collection of snap-
shots. They may also be projected in any standard single frame
projector, and if made as motion picture film they may be pro-
jected in full relief by any standard home movie projector.
Polarization anaglyphs are made from normal stereo negatives,
but instead of being printed in complementary dyes, they are
printed by the dye transfer process in a dye which crystallizes in
dichroic form. There are many substances which will react cor-
rectly, but the formula developed by the manufacturers is ex-
cellent.
The secret lies in the base used. This is an optically active
plastic (transparent) base. By printing the image on the two sides
of this active base in the correct crystalline image, the two images
are polarized at go degrees to each other. The examination of
such a dual print through the usual 3D goggles used for common
stereo projection produces the full stereo effect.