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-invariant features for pattern recognition. Each feature depends on the entire image. This approach has a good discrimination capability. Optical real-time implementation of the on-axis continuous phase-only circular harmonic filters by the use of a commercial liquid-crystal television is shown. A harmonic analysis shows that the phase-mostly filter can tolerate coupled amplitude modulation at the acceptable expense of the output signal-to-noise ratio. An optical experiment of the geometrical approach of multiple circular harmonic filters for a multiple-image input is described. The cross-correlation peaks between the individual filters and the clutter are eliminated, because they are not in good locations.

[1]  Danny Roberge,et al.  Optical implementation of the phase-only composite filter using liquid crystal television , 1994, Defense, Security, and Sensing.

[2]  H H Arsenault,et al.  Rotation invariant phase-only and binary phase-only correlation. , 1989, Applied optics.

[3]  Y Sheng,et al.  Programmable optical phase-mostly holograms with coupled-mode modulation liquid-crystal television. , 1995, Applied optics.

[4]  D Casasent,et al.  Advanced distortion-invariant minimum average correlation energy (MACE) filters. , 1992, Applied optics.

[5]  H Stark,et al.  Rotation-invariant pattern recognition using a vector reference , 1984 .

[6]  R. Juday Optimal realizable filters and the minimum Euclidean distance principle. , 1993, Applied optics.

[7]  Y Sheng,et al.  Fast design of circular-harmonic filters using simulated annealing. , 1993, Applied optics.

[8]  H H Arsenault Rotation-invariant digital pattern recognition using circular harmonic expansion: author's reply to comments. , 1989, Applied optics.

[9]  Donald W. Sweeney,et al.  Iterative technique for the synthesis of optical-correlation filters , 1986 .

[10]  P E Danielsson Rotation-invariant digital pattern recognition using circular harmonic expansion: a comment. , 1989, Applied optics.

[11]  J L Horner,et al.  Metrics for assessing pattern-recognition performance. , 1992, Applied optics.

[12]  Takeshi Takahashi,et al.  Phase-only matched filtering with dual liquid-crystal spatial light modulators , 1995, Optics & Photonics.

[13]  H H Arsenault,et al.  Object detection from a real scene using the correlation peak coordinates of multiple circular harmonic filters. , 1989, Applied optics.

[14]  Richard D. Juday,et al.  Experimental correlator results with coupled modulators and advanced metrics , 1994, Optics & Photonics.

[15]  H H Arsenault,et al.  Properties of the circular harmonic expansion for rotation-invariant pattern recognition. , 1986, Applied optics.

[16]  H H Arsenault,et al.  Rotation-invariant digital pattern recognition using circular harmonic expansion. , 1982, Applied optics.

[17]  J Shamir,et al.  Circular harmonic phase filters for efficient rotationinvariant pattern recognition. , 1988, Applied optics.

[18]  J W Goodman,et al.  Optimal maximum correlation filter for arbitrarily constrained devices. , 1989, Applied optics.

[19]  H H Arsenault,et al.  Contrast-invariant pattern recognition using circular harmonic components. , 1985, Applied optics.

[20]  Y Sheng,et al.  Optical on-axis imperfect phase-only correlator using liquid-crystal television. , 1993, Applied optics.

[21]  Yunlong Sheng,et al.  Method for determining expansion centers and predicting sidelobe levels for circular-harmonic filters , 1987 .