21 August 1987 Compound Circular Harmonic Filters
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Proceedings Volume 0754, Optical and Digital Pattern Recognition; (1987); doi: 10.1117/12.939999
Event: OE LASE'87 and EO Imaging Symposium, 1987, Los Angeles, CA, United States
In this paper a compound rotation-invariant filtering technique is developed which leads to sharp cross-correlation peaks for desired targets, while suppressing random noise and unwanted target correlations. The basic compound filter structure consists of a weighted sum of the cross-correlations between several circular harmonic filters (CHF's) and the input image. In the design procedure, the weights are constrained so that the compound filter output has a peak value of 1, for the desired target. Measures of random noise, and deterministic noise due to correlations with unwanted targets, are minimized with respect to the weights. The signal-to-noise ratio (SNR) of the compound filter is therefore maximized. Some limits to the performance of the technique are discussed. The output magnitude squared cross-correlation functions form a non-orthogonal set of functions. Therefore, the SNR could be made arbitrarily large if the functions were linearly independent and a very large number of CHF's were available. Examples illustrating the filter performance are given. Extensions of this work are discussed.
© (1987) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. T. Manry, "Compound Circular Harmonic Filters", Proc. SPIE 0754, Optical and Digital Pattern Recognition, (21 August 1987); doi: 10.1117/12.939999; https://doi.org/10.1117/12.939999

Signal to noise ratio

Image filtering

Optical pattern recognition

Optical filters

Interference (communication)

Digital filtering

Electronic filtering

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