Abstract

Optical-correlation filters that are translationally and rotationally invariant are made target specific by incorporating all the angular harmonics of the target image. An iterative design method similar to the technique of convex projections allows the image angular harmonics to be rephased so that the filter exhibits a constant-amplitude rotational response. Rotating this filter in the Fourier plane forms the Fourier summation of all angular harmonics of the input image. Ari image to be detected must have angular-harmonic terms that have an amplitude and a phase that are keyed exactly to the target image. This lock-and-tumbler filter exhibits excellent discrimination capability while preserving rotational invariance.

© 1986 Optical Society of America

Rotationally invariant correlation filtering for multiple images

George F. Schils and Donald W. Sweeney
J. Opt. Soc. Am. A 3(7) 902-908 (1986)

Rotationally invariant correlation filtering

George F. Schils and Donald W. Sweeney
J. Opt. Soc. Am. A 2(9) 1411-1418 (1985)

Experimental use of iteratively designed rotation invariant correlation filters

Donald W. Sweeney, Ellen Ochoa, and George F. Schils
Appl. Opt. 26(16) 3458-3465 (1987)

Iterative technique for the synthesis of distortion-invariant optical correlation filters

George F. Schils and Donald W. Sweeney
Opt. Lett. 12(5) 307-309 (1987)

Optical processor for recognition of three-dimensional targets viewed from any direction

George F. Schils and Donald W. Sweeney
J. Opt. Soc. Am. A 5(8) 1309-1321 (1988)