Well, I'll admit I have never seen this, but here is what I can say.
Polarization basics:
Chemical polarizers are made of long molecules, like the bars of a jail cell, say along the y-axis. Polarized light on the other hand is made of an E-field (electric field) that oscillates in one direction (y or x) perpendicular to the direction of the light beam (z). (We can practically always ignore the corresponding magnetic field in (x) when speaking of polarization.) Regular light has an oscillating E-field in both (y) and (x).
If y-polarized light hits y-polarized molecule (jail door), it can be totally absorbed, or reflected. The conducting electrons will run along the long molecules and either absorb or reflect the light.
On the other hand, x-polarized light will go through y-polarized molecule, since the conduction electrons can't follow such E-fields.
Regular light will be half transmitted, half absorbed + reflected.
Your system:
I suspect the picture you saw contained such y-oriented long-chained conducting molecules, that formed a picture by themselves, so that y-polarized light was reflected off, and allowed you to see it. With regular light (y + x), the extra reflection by (x) added another picture (perhaps nothing by itself) to produce the illusion of a completely new picture.
Were there similarities between the pictures? (especially in color and black areas?) Were the picture and light sources handheld or fixed together in some table-top frame?
