Circular harmonic phase filters for efficient rotationinvariant pattern recognition.

A generalized approach for pattern recognition using spatial filters with reduced tolerance requirements was described in some recent publications. This approach leads to various possible implementations such as the composite matched filter, the circular harmonic matched filter, or the composite circular harmonic matched filter. The present work describes new examples leading to very high selectivity filters retaining rotation invariance and reduced requirements on device resolution. Computer simulations and laboratory experiments show the advantages of this approach.