The usefulness of combining stereogram techniques with cellular neural netw
ork (CNN) analogic procedures in stereo depth extraction has been demonstra
ted before. Due to the local processing philosophy in the CNN paradigm, the
detailed and well-established knowledge of local stereogram properties is
of high importance. The paper gives an algorithmic definition for synthetic
stereograms; a means for structural analysis of different types of random
stereograms. In order to confine the generally propagating effect of three-
dimensional (3-D) surface features into a restricted neighborhood in a ster
eogram, the concept of difference stereograms and the related difference su
rface is introduced for coding local surface variations into stereograms, T
he difference stereogram, with its local structure, is especially suitable
for CNN processing, and it is closely connected to the pattern projection t
echnique of depth extraction.