The mapping of complex-valued functions onto phase-only spatial light
modulators is examined. Random phase encoding effectively adds amplitu
de control to the phase-only filter and can be used to trade off syste
matic errors of the phase-only filter for random errors. This is illus
trated for the problem of recognizing a three-dimensional object from
arbitrary views. The complex-valued composite filters that constitute
a filter bank design are encoded by phase-only and pseudorandom method
s. The best recognition probabilities are achieved by blending the two
methods so that only the smallest amplitudes are randomly encoded. (C
) 1996 Optical Society of America