Optical Superresolution and Visual Hyperacuity

Gerald Westheimer
Division of Neurobiology, MCB
UC Berkeley

Once it is realized that some spatial visual thresholds, such as those for
vernier alignment, can be a small fraction of the classical Rayleigh
resolution limit, the optical and information-theoretical consequences of
these hyperacuity responses have to be faced.  Transferring discussion
into the spatial-frequency domain, in which the diffraction limit is
embodied in the cut-off frequency, makes it clear that no physical
principles are violated. More relevant are the modern practices of optical
or diffractive superresolution, in which stratagems are employed to shift
high-frequency target components into the passband of an imaging device
where they require sophisticated procedures for object reconstitution.  In
particular, the human visual system utilizing mechanism, now termed
geometrical superresolution, to overcome barriers to image-information
retrieval imposed by the structure of the detecting apparatus.