Resolution limits of holographic mapping filters for geometric coordinate transformations.

A recently proposed position, rotation, and scale-invariant optical pattern recognition system using a holographic logpolar mapping filter is analyzed with respect to resolution and accuracy. The limits are set by the resolution of the mapping filter, which must have a bandwidth proportional to the square of the input bandwidth. With 1800 x 1800 pixels in the computer-generated mapping filter, we get a maximum input field of 24 x 24 pixels and an angular resolution of 4.80 degrees . Determination of the position of the input object is possible with at best 50% relative accuracy, and, in practice, multiobject capability is highly questionable. Numerical simulations and experimental evidence support the resolution limits found.