Modified Two-Focal-Length Optical Correlator

Fielding, Kenneth H.; Horner, Joseph L.; Makekau, Charles K.

doi:10.21236/ada231005

Cited by 2 publications

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“…It is based on a 2f correlator setup discussed in a recent paper by Fielding et al 16 This allows for a relatively shorter length of the correlator and variable scaling of the input image in the Fourier plane. The input image which in this case was a 128 x 128 pixelated gray level photographic slide is set just after lens 1.…”

Section: Methodsmentioning

confidence: 99%

Binary phase-only filter associative memory

Kane¹,

Hemmer²,

Woods³

et al. 1991

SPIE Proceedings

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An associative memory is implemented using a Binary Phase OnlyFilter as the memory element. In the current architecture, if the input contains any part of the set of stored memories, then the entire set is retrieved at the output. In addition, the sharp autocorrelation peak and the high signal to noise ratio allows operation without necessitating a thresholding device. INTRODUCTIONThere are two main approaches to implementing all optical associative mnemnories.17 The first approach relies on optical vector matrix multiplication based on spatial light modulators and Light Emitting Diodes.1 The second approach which operates directly on two-dimensional input images utilizes holograms as the storage media and some kind of saturable gain element or aperture as the threshold iuechanism.27Holograms are used as memory elements because of their high storage capability. Recently Oppenheimn and Limn have shown that the phase information is the important part for reconstructing the information.8Following this, Homer et al showed that the phase or binarized phase could be used for image correlation.911 According to the definition provided by Homer, the signal to noise ratio of the BPOF correlator was 4.5 times higher, while the height of the correlation peak was 40 times higher and the efficiency was 2.5 times higher than found in classical matched filter correlators.1213 This suggests, therefore, that the binarized phase information alone can be used to construct Ithe memory element.Most holographic associative memories share a similar architecture which consists of a correlator with a thresholding device such as a retroreflecting phase conjugate mirror utilizing a photorefractive crystal such as BaTiO3, a pinhole array in the correlation plane with an ordinary mirror, or a optical fiber used as a spatial filter.17 In this paper, we replace the holographic element with a binary phase only filter. O-8194-0692-9/91/$4.OO SPIE Vol. 1564 OpticalInformation Processing Systems andArchitectures 111(1991) / 511 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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Section: Methodsmentioning

confidence: 99%

Binary phase-only filter associative memory

Kane¹,

Hemmer²,

Woods³

et al. 1991

SPIE Proceedings

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“…Li et al used joint wavelet transform to extract edge features from the input image to eliminate the influence of noise [5] . Fielding et al improved the system capability of identifying cross-correlation peaks by adopting binary transform to the joint power spectrum (JPS) image [6] . Chen et al introduces discrete cosine transform (DCT) [7] and highpass filter [8] respectively to preprocess the JPS image to further improve the system performance.…”

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confidence: 99%

基于光/数混合联合变换相关器进行像移测量的改进型数字处理方法

Yi¹,

Zhao²,

Li³

et al. 2010

中国光学快报

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Hybrid opto-digital joint transform correlator (HODJTC) is effective for image motion measurement, but it is different from the traditional joint transform correlator because it only has one optical transform and the joint power spectrum is directly input into a digital processing unit to compute the image shift. The local cross-correlation image can be directly obtained by adopting a local Fourier transform operator. After the pixel-level location of cross-correlation peak is initially obtained, the up-sampling technique is introduced to relocate the peak in even higher accuracy. With signal-to-noise ratio ≥ 20 dB, up-sampling factor k ≥ 10 and the maximum image shift ≤ 60 pixels, the root-mean-square error of motion measurement accuracy can be controlled below 0.05 pixels.

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Modified Two-Focal-Length Optical Correlator

Cited by 2 publications

References 0 publications

Binary phase-only filter associative memory

Binary phase-only filter associative memory

基于光/数混合联合变换相关器进行像移测量的改进型数字处理方法

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