Optical implementation of a photorefractive joint transform correlator with wavelet filters

Zhang, H; Cartwright, Colin M.; Ding, Mei-Song; Gillespie, W. A.

doi:10.1016/s0030-4018(00)00760-4

Cited by 12 publications

(4 citation statements)

References 20 publications

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“…Symmetrical wavelets such as CW and Morlet have found many applications, including astronomy, [36][37][38] physics, 39,40 neural networks, 41,42 image processing, 4 pattern recognition, 43 digital watermarking, 44 chemistry, 45 optics, 46 and structural analysis. 47 However, they have often been overlooked with work toward this area has recently been very limited.…”

Section: Discussion and Further Workmentioning

confidence: 99%

Hyperbolic wavelet family

Lê

Dabke

Egan

2004

Review of Scientific Instruments

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Time-frequency analysis with the continuous wavelet transform Am.This article reports early results on digital implementation of first-and nth-order hyperbolic wavelets whose important parameters are explicitly expressed and numerically estimated. The first-order hyperbolic, Morlet and Choi-Williams wavelets are compared in detail by numerically calculating their band-peak frequencies, minimum numbers of sampling points, scale resolutions, and maximum numbers of scales. One of the main aims is to show that there exists a strong link among time-frequency kernels and wavelets. This relationship helps to expand and link timefrequency and wavelet approaches to signal analysis. One example of using the hyperbolic wavelet for speech recognition is also given.

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Section: Discussion and Further Workmentioning

confidence: 99%

Hyperbolic wavelet family

Lê

Dabke

Egan

2004

Review of Scientific Instruments

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“…For instance, one can make a hybrid wavelet-joint transform correlator in which additional wavelet-transform filters are employed, making the JTC less sensitive to scale and rotational non-invariances. Moreover, wavelet filtration enables to the increase of signal-to-noise ratio and correlation peak sharpness due to its edge enhancement nature which is useful for target recognition [ 56 , 57 , 58 ]. Thus, CdF 2 crystals with bistable impurity centers can be considered as appropriate holographic media for fast hybrid wavelet-joint transform correlators.…”

Section: Holographic Optical Elements Based On Cdf 2 mentioning

confidence: 99%

Semiconductor CdF2:Ga and CdF2:In Crystals as Media for Real-Time Holography

2012

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Monocrystalline cadmium fluoride is a dielectric solid that can be converted into a semiconductor by doping with donor impurities and subsequent heating in the reduction atmosphere. For two donor elements, Ga and In, the donor (“shallow”) state is a metastable one separated from the ground (“deep”) state by a barrier. Photoinduced deep-to-shallow state transition underlies the photochromism of CdF2:Ga and CdF2:In. Real-time phase holograms are recorded in these crystals capable of following up optical processes in a wide frequency range. The features of photochromic transformations in CdF2:Ga and CdF2:In crystals as well as holographic characteristics of these media are discussed. Exemplary applications of CdF2-based holographic elements are given.

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“…The Mexican hat wavelet comes from the second derivative of a Gaussian function and is defined, in its 2D form, as [12],…”

Section: Wavelet Functionsmentioning

confidence: 99%

“…In that sense, the traditional architectures of correlators, the Vander Lugt correlator or conventional matched filtering (CMF), and the joint transform correlator (JTC), have been a subject of constant research. In particular, for example, wavelet transform-based photorefractive filtering systems and correlators have been demonstrated [9][10][11][12][13][14][15]. Correlation allows obtaining the degree of correspondence between a reference image and a target one.…”

Section: Introductionmentioning

confidence: 99%