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1 May 1990 Nonlinear baseband filters for optical pattern recognition
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A nonlinear filter based image correlator is investigated. The linear filter is expressed as the real part of the conventional matched filter. This baseband function contains the amplitude and phase of the Fourier transform of the reference signal. The real baséband filter function is then applied to a nonlinear device to produce the nonlinear filter function. Analytical expressions for the nonlinear filter are provided. The effects of the nonlinear transfer characteristics on the correlation signals at the output plane are investigated. The correlation signals are determined in terms of the nonlinear characteristics used to transform the filter. We show that the nonlinear filter results is a sum of infinite harmonic terms. Each harmonic term is envelope modulated due to the nonlinear characteristics of the device, and phase modulated by m times the phase modulation of the linear filter function.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bahram Javidi, Carol Ruiz, and Jack Ruiz "Nonlinear baseband filters for optical pattern recognition", Proc. SPIE 1211, Computer and Optically Formed Holographic Optics, (1 May 1990);

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