  Pseudoscopic (inverted depth) images that keep a continuous parallax were
shown to be possible by use of a double diffraction process intermediated by a
slit. One diffraction grating directing light to the slit acts as a wavelength
encoder of views, while a second diffraction grating decodes the projected
image. The process results in the enlargement of the image under common white
light illumination up to infinite magnification at a critical point. We show
that this point corresponds to another simple-symmetry object-observer system.
Our treatment allows us to explain the experience by just dealing with main ray
directions.
