Non-linear filters have been used in many signal processing applications, for example, to obtain optimum signal extraction or detection in the presence of random noise. The weighted median filter (WMF), of which the s...
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ISBN:
(纸本)081864222X
Non-linear filters have been used in many signal processing applications, for example, to obtain optimum signal extraction or detection in the presence of random noise. The weighted median filter (WMF), of which the standard median is a special case, is a novel non-linear technique designed for 2D imageprocessing. A major advantage of the WMF is its flexibility in design to deal with a wide variety of properties. This paper describes a commonly used class W(4,4,1) of the WMF. As with most non-linear methods, the computational demands of this technique are high and require a non-trivial number of `expensive' operations. A data parallel approach for efficient implementation of the WMF is described and implemented on two architecturally dissimilar supercomputers, the Convex C3840 and the Connection Machine CM-200. An analysis of the performance obtained from these two high performance parallel platforms is presented.
The proceedings contain 29 papers. The topic discussed include: algorithm for classification of multispectral data and its implementation on a massively parallel computer;convergence measure and some parallel aspects ...
The proceedings contain 29 papers. The topic discussed include: algorithm for classification of multispectral data and its implementation on a massively parallel computer;convergence measure and some parallel aspects of Markov-chain Monte Carlo algorithms;evidential reasoning based on Dempster-Shafer theory and its application to medical image analysis;cluster approximations for statistical imageprocessing;image recovery and segmentation using competitive learning in a layered network;feature competition and domain of attraction in artificial-perceptron pattern recognizer;and probabilistic spectral feature extraction technique for neural networks.
A new inversion scheme for reconstruction of images from projections based upon the slope-intercept form of the discrete Radon transform is presented. A seminal algorithm for the forward and the inverse transforms was...
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A new inversion scheme for reconstruction of images from projections based upon the slope-intercept form of the discrete Radon transform is presented. A seminal algorithm for the forward and the inverse transforms was proposed by Beylkin in 1987. However, as proposed, the original algorithm demonstrated poor dispersion characteristics for steep slopes and could not invert transforms based upon nonlinear slope variations. By formulating the computation as a discrete computation of the continuous Radon transform formula, we explicitly derive fast new generalized inversion methods that overcome the original shortcomings. The generalized forward (FRT) and inverse algorithm (IFRT) proposed are fast, eliminate interpolation calculations, and convert directly between a raster scan grid and a rectangular/polar grid in one step. Part ii of this paper describes the implementation of the algorithm on a massively parallel computer, and a new time-domain formulation.
The processing of Boolean imagery compressed by runlength encoding (RLE) frequently exhibits greater computational efficiency than the processing of uncompressed imagery, due to the data reduction inherent in RLE. In ...
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A new method for classification of multi-spectral data is proposed. This method is based on fitting mixtures of multivariate Gaussian components to training and unlabeled samples by using the EM algorithm. Through a b...
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As a time-sequential and Bayesian front-end for image sequence processing, we consider the square root information (SRI) realization of Kalman filter. The computational complexity of the filter due to the dimension of...
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ISBN:
(纸本)0819411361
As a time-sequential and Bayesian front-end for image sequence processing, we consider the square root information (SRI) realization of Kalman filter. The computational complexity of the filter due to the dimension of the problem -- the size of the state vector is on the order of the number of pixels in the image frame -- is decreased drastically using a reduced-order approximation exploiting the natural spatial locality in the random field specifications. The actual computation for the reduced-order SRI filter is performed by an iterative and distributed algorithm for the unitary transformation steps, providing a potentially faster alternative to the common QR factorization-based methods. For the space-time estimation problems, near- optimal solutions can be obtained in a small number of iterations (e.g., less than 10), and each iteration can be performed in a finely parallel manner over the image frame, an attractive feature for a dedicated hardware implementation.
We examine methods to assess the convergence of Markov chain Monte Carlo (MCMC) algorithms and to accelerate their execution via parallel computing. We propose a convergence measure based on the deviations between sim...
ISBN:
(纸本)0819412813
We examine methods to assess the convergence of Markov chain Monte Carlo (MCMC) algorithms and to accelerate their execution via parallel computing. We propose a convergence measure based on the deviations between simultaneously running MCMC algorithms. We also examine the acceleration of MCMC algorithms when independent parallel sampler are used and report on some experiments with coupled samplers. As applications we use small Ising model simulations and a larger medical imageprocessing algorithm.
A computer-aided quantitative method for a complex analysis of gel electrophoretograms is presented. The analysis consists of several steps: (i) determination of the background image by methods of mathematical morphol...
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A computer-aided quantitative method for a complex analysis of gel electrophoretograms is presented. The analysis consists of several steps: (i) determination of the background image by methods of mathematical morphology and its subtraction from the gel image, (ii) selection of an appropriate part of the gel lane including curved lanes and lanes with a nonuniform width, (iii) computation of the lane densitogram by averaging several lane-parallel scans, (iv) decomposition of the lane densitogram into component bands using a data selecting algorithm and Marquardt's minimizer. Several different functions for component bands are utilized. It is shown that the densitogram can be decomposed into component bands with reasonable accuracy only if an appropriate model function is chosen. The algorithms are tested on several different gel electrophoretograms which show typical features as a nonuniform background, curved lanes, an asymmetrical band shape and a superposition of small bands on the shoulders of big ones. It is shown that overlapped bands are best approximated by an asymmetrical Gaussian curve and an asymmetrical Gauss-Cauchy function. Linear response to the serial dilution of the protein sample is tested.
Describes an approach to edge detection particularly suited for implementation on distributed-memory massively parallel MIMD machines. One of the main tasks of this work is the identification of an optimal edge thresh...
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Describes an approach to edge detection particularly suited for implementation on distributed-memory massively parallel MIMD machines. One of the main tasks of this work is the identification of an optimal edge threshold, i.e. the value of the luminance gradient allowing one to identify actual edge pixels. Such identification has been done by adopting a local approach, where the image is a-priori partitioned into small square windows, and the optimal threshold is selected by ranking the outputs produced by several thresholds inside each window. The innovative contributions of this work lie in the fact that, by partitioning the image in suitably small windows, the probability of having only one edge chain in each window is maximized (thus enhancing the effectiveness of the optimal threshold selection criterion), and the scalability of the application is ensured (due to the high number of simple processing tasks into which the algorithm is subdivided).< >
Nonlinear filters have been used in many signal processing applications, for example, to obtain optimum signal extraction or detection in the presence of random noise. The weighted median filter (WMF), of which the st...
详细信息
Nonlinear filters have been used in many signal processing applications, for example, to obtain optimum signal extraction or detection in the presence of random noise. The weighted median filter (WMF), of which the standard median is a special case, is a novel nonlinear technique designed for 2D imageprocessing. A major advantage of the WMF is its flexibility in design to deal with a wide variety of properties. This paper describes a commonly used class W(4,4,1) of the WMF. AS with most nonlinear methods, the computational demands of this technique are high and require a non-trivial number of "expensive" operations. A data parallel approach for efficient implementation of the WMF is described and implemented on two architecturally dissimilar supercomputers, the Convex C3840 and the Connection Machine CM-200. An analysis of the performance obtained from these two high performance parallel platforms is presented.< >
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