Rotationally invariant pattern recognition in a photorefractive joint transform correlator using circular harmonic filters and the wavelet transform

Hui Zhang, Colin M. Cartwright, Mei-Song Ding, Zhao-Qi Wang, Bao-Lai Liang, W. Allan Gillespie

Research output: Contribution to journalArticle

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Abstract

A photorefractive joint transform correlator using circular harmonic filters and the wavelet transform for high discriminant and rotationally invariant pattern recognition is reported. In the experimental implementation, a photorefractive crystal, BSO, is used as the dynamic holographic medium and a bank of wavelet functions, derived from a mother Mexican-hat wavelet have been selected to achieve a band-pass operation in the Fourier domain. The zero-order and second-order circular harmonic components are used in the investigation. It is shown that, with the proper dilation factors, there is a trade-off between peak correlation intensity and signal-to-noise ratio (SNR) with the wavelet transform filters. With the second-order circular harmonic, an improvement of 63% in the SNR is achieved with only a 4% loss in the peak correlation intensity.
Original languageEnglish
Pages (from-to)383-391
Number of pages9
JournalOptics Communications
Volume195
Issue number5-6
DOIs
StatePublished - 15 Aug 2001

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Fistula
harmonics
Wavelet transforms
wavelet analysis
filters
Correlators
Middle Ear
Pattern recognition
Signal to noise ratio
correlators
pattern recognition
signal to noise ratios
Methacholine Compounds
Diflucortolone
Spontaneous Fractures
Inner Ear
Photorefractive crystals
crystals

Cite this

Zhang, Hui; Cartwright, Colin M.; Ding, Mei-Song; Wang, Zhao-Qi; Liang, Bao-Lai; Gillespie, W. Allan / Rotationally invariant pattern recognition in a photorefractive joint transform correlator using circular harmonic filters and the wavelet transform.

In: Optics Communications, Vol. 195, No. 5-6, 15.08.2001, p. 383-391.

Research output: Contribution to journalArticle

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Rotationally invariant pattern recognition in a photorefractive joint transform correlator using circular harmonic filters and the wavelet transform. / Zhang, Hui; Cartwright, Colin M.; Ding, Mei-Song; Wang, Zhao-Qi; Liang, Bao-Lai; Gillespie, W. Allan.

In: Optics Communications, Vol. 195, No. 5-6, 15.08.2001, p. 383-391.

Research output: Contribution to journalArticle

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AU - Zhang,Hui

AU - Cartwright,Colin M.

AU - Ding,Mei-Song

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AU - Liang,Bao-Lai

AU - Gillespie,W. Allan

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AB - A photorefractive joint transform correlator using circular harmonic filters and the wavelet transform for high discriminant and rotationally invariant pattern recognition is reported. In the experimental implementation, a photorefractive crystal, BSO, is used as the dynamic holographic medium and a bank of wavelet functions, derived from a mother Mexican-hat wavelet have been selected to achieve a band-pass operation in the Fourier domain. The zero-order and second-order circular harmonic components are used in the investigation. It is shown that, with the proper dilation factors, there is a trade-off between peak correlation intensity and signal-to-noise ratio (SNR) with the wavelet transform filters. With the second-order circular harmonic, an improvement of 63% in the SNR is achieved with only a 4% loss in the peak correlation intensity.

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