Abstract

The simulated annealing (SA) algorithm based on entropy optimization is a technique of synthesizing distortion-invariant matched filters capable of discriminating very similar images. The synthesis of rotation-invariant filters using modified SA-based filter equations and their tolerance to distortions are studied. The filters are trained with true class images rotated in-plane at 3° intervals between 0° and 360°. A total of seven filters are required over the whole range for both CCD or thermal images. Optical correlation in a hybrid digital-optical correlator results in an unwanted zero-order dc along with two first-order $\left(\pm 1\right)$ correlation peaks. A chirp function multiplied with the filter separates out the three peaks to three different planes, and only one peak in focus is captured in a camera. The performance of the modified SA-based filter has been studied in comparison to the conventional SA filter as well as with other filters.

© 2007 Optical Society of America

Log-polar transform-based wavelet-modified maximum average correlation height filter for distortion invariance in a hybrid digital-optical correlator

Amit Aran, Naveen K. Nishchal, Vinod K. Beri, and Arun K. Gupta
Appl. Opt. 46(33) 7970-7977 (2007)

Wavelet-modified maximum average correlation height filter for rotation invariance that uses chirp encoding in a hybrid digital-optical correlator

Shilpi Goyal, Naveen K. Nishchal, Vinod K. Beri, and Arun K. Gupta
Appl. Opt. 45(20) 4850-4857 (2006)

Spatial-temporal correlation filter for in-plane distortion invariance

Abhijit Mahalanobis, B. V. K. Vijaya Kumar, and David Casasent
Appl. Opt. 25(23) 4466-4472 (1986)

Filter-feature-based rotation-invariant joint Fourier transform correlator

Farid Ahmed and Mohammad A. Karim
Appl. Opt. 34(32) 7556-7560 (1995)

Distortion tolerant correlation filter design

Kaveh Heidary
Appl. Opt. 52(12) 2570-2576 (2013)