THEORY AND OPTICAL IMPLEMENTATION OF THE GEOMETRICAL APPROACH OF MULTIPLE CIRCULAR HARMONIC FILTERS

The circular harmonic filter contains only one component of the image. Its discrimination capability has been questionable. The geometrical approach of multiple circular harmonic filters uses relative locations of the correlation peaks as the rotation-, shift-, and intensity-inva riant features for pattern recognition. Each feature depends on the en tire image. This approach has a good discrimination capability. Optica l real-time implementation of the on-axis continuous phase-only circul ar harmonic filters by the use of a commercial liquid-crystal televisi on is shown. A harmonic analysis shows that the phase-mostly filter ca n tolerate coupled amplitude modulation at the acceptable expense of t he output signal-to-noise ratio. An optical experiment of the geometri cal approach of multiple circular harmonic filters for a multiple-imag e input is described. The cross-correlation peaks between the individu al filters and the clutter are eliminated, because they are not in goo d locations.