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Nonlinear filtering in object and Fourier space in a joint transform optical correlator: comparison and experimental
Applied Optics
|November 6, 2010
Summary
This study compares nonlinear filtering techniques for joint transform correlators. Results show binarization and spatial envelope removal in Fourier space enhance performance.
Area of Science:
- Optics and Photonics
- Information Processing
Background:
- Joint transform correlators (JTCs) are widely used for pattern recognition.
- Nonlinear filtering is crucial for improving JTC performance by reducing noise and enhancing correlation peaks.
- Existing methods often involve complex filtering in either object or Fourier domains.
Purpose of the Study:
- To investigate and compare various nonlinear filtering techniques for joint transform correlators.
- To evaluate the effectiveness of filters applied in both object space and Fourier domain.
- To introduce and assess a novel method for spatial envelope removal in the Fourier domain.
Main Methods:
- Simulation and experimental implementation of a compact joint transform correlator.
- Computation of phase and inverse filters in the object space.
- Application of inverse Fourier transforms to generate object-space references.
- Binarization of the joint power spectrum in the Fourier domain.
- Comparison with a new procedure for spatial envelope removal.
Main Results:
- Phase and inverse filters were successfully computed and utilized as references in object space.
- Binarization of the power spectrum demonstrated its effectiveness.
- The novel spatial envelope removal procedure showed promising results in the Fourier domain.
- Experimental validation confirmed simulation outcomes across different filtering scenarios.
Conclusions:
- Nonlinear filtering significantly impacts joint transform correlator performance.
- Both object-space and Fourier-domain filtering offer viable strategies for performance enhancement.
- The proposed spatial envelope removal technique presents a valuable addition to JTC nonlinear filtering methods.
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