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Medical Imaging iv: PACS System Design and Evaluation

作者： Wong, A. Lou, S.L. Stewart, B.K. Chan, K.K. Valentino, D.J. Huang, H.K. UCLA Sch of Medicine Los Angeles United States

ISBN: (纸本)0819402788

We have evaluated the performance of Ethermet, Fiber distributed Data Interface (FDDI) and Canstar Super 100 networks in a multimodal Picture Archiving and Communication System (PACS) environment. image data transfer rates were measured for SUN workstations and PC/ATs running TCP/IP communication protocols. The communication between two computers was on a server-client basis and all transfer rates were measured between computer memories in order to eliminate the bottlneck imposed by storage devices. Four test models were used to evaluate the performance of the three individual networks: bidirectional, centralized, parallel, and relay models. This paper describes the methods of network throughput evaluation using these four models and presents the resulting performance data for the three networks tested.

关键词： Imaging Techniques

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A parallel distributed algorithm for feature extraction and disparity analysis of computer images

A parallel distributed algorithm for feature extraction and ...

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International Symposium on parallel and distributed processing (IPDPS)

作者： M.S. Mousavi R.J. Schalkoff AT and T Bell Laboratories Inc. Middletown NJ USA Department of Electrical & Computer Engineering Clemson University Clemson SC USA

A parallel distributed processing method for extracting features in stereo images is presented. The algorithm is edge-based and employs the epipolar constraint. First edges are detected in a multilayered network using two methods of locating the magnitude of directional first derivatives and the zero-crossing of second derivatives of smoothed images. The combined edge detection process helps to eliminate 'phantom' edges. Then features that are likely to be detectable in both images are selected. These features are edge intervals and edge orientation, that is, the intersection of image edges with the epipolar line and the corresponding slope of the edges at those points. The feature extraction process is implemented in a two-layered parallel distributed processing model. The first layer provides edge interval representations. The second layer computes a similarity of measure for each pair of primitive matches which are then forwarded to the second stage of the algorithm. The purpose of the second stage is to turn the difficult pixel correspondence problem into a constraint satisfaction problem by imposing relational constraints. This constraint satisfaction is then solved using a neural network. The results of computer simulations are presented to demonstrate the effectiveness of the approach.< >

关键词： distributed algorithms Feature extraction image analysis Algorithm design and analysis Concurrent computing distributed computing image edge detection Stereo vision Neural networks distributed processing

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parallel algorithms for determining k-width- connectivity in binary images

Parallel algorithms for determining k-width- connectivity in...

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International Symposium on parallel and distributed processing (IPDPS)

作者： F. Dehne S.E. Hambrusch School of Computer Science Carleton University Ottawa Canada Department of Computer Sciences Purdue University West Lafayette IN USA

The authors consider a new form of connectivity in binary images, called k-width-connectivity. Two pixels a and b of value '1' are in the same k-width-component if and only if there exists a path of width k such that a is one of the k start pixels and b is one of the k end pixels of this path. The authors present characterisations of the k-width-components and show how to determine the k-width-components of an n*n image in O(n) and O(log/sup 2/ n) time on a mesh of processors and hypercube, respectively, when the image is stored with one pixel per processor. The methods use a reduction of the k-width-connectivity problem to the 1-width-connectivity problem. A distributed, space-efficient encoding of the k-width-components of small size allows the solution to be represented using O(l) registers per processor. The hypercube algorithm also implies an algorithm for the shuffle-exchange network.< >

关键词： parallel algorithms Pixel Hypercubes Computer science Concurrent computing Encoding Registers Fault tolerance Councils Contracts

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HIERARCHICAL parallel MEMORY-SYSTEMS AND MULTIPERIODIC SKEWING SCHEMES

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JOURNAL OF parallel AND distributed COMPUTING 1989年第2期7卷 355-367页

作者： TEL, G WIJSHOFF, HAG STATE UNIV UTRECHT DEPT COMP SCI3508 TB UTRECHTNETHERLANDS

The theory of skewing schemes deals with the problem of distributing data in parallel memories, in such a way that parallel computations can proceed efficiently. Until now skewing schemes have been studied from the viewpoint of the BSP and ILLIAC iv architectures and image processing. In the present paper we are concerned with hierarchically organized parallel memory systems, for which a new class of skewing schemes is introduced, namely the multiperiodic skewing schemes. We show that multiperiodic skewing schemes are an extension of both the periodic skewing schemes and the diamond schemes for traditional parallel memories. It is also shown that the schemes work out very well for many applications and, in particular, a bound on the minimum number of memory banks needed for certain applications is derived. Furthermore, multiperiodic skewing schemes can be represented at the cost of only a small amount of space, which makes them of practical interest.

关键词： Computer Systems, Digital

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SYSTEM FOR LOSSLESS DIGITAL image-CODING DECODING

SYSTEM FOR LOSSLESS DIGITAL IMAGE-CODING DECODING

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CONF ON VISUAL COMMUNICATIONS AND image processing 4

作者： TORBEY, HH MEADOWS, HE Columbia University (United States)

ISBN: (纸本)0819402389

This study revisits simple methods, subsampling and modulo differentiation, to combine them in a system suitable for operation in ISDN as well as non-ISDN environments with good overall performance. The modulo difference of selected pairs of pixels in a digital image enables the design of a hierarchal code which represents the original digital image without any information loss. The pixels are selected by pairing together consecutive non-overlapping pixels in the original image and then in successive subsampled versions of it. The subsampling is 2:1 and, as the pairing, is alternated horizontally and vertically. This algorithm uniquely combines hierarchal and parallel processing. Further processing of the hierarchal code through an entropy coder achieves good compression. If a Huffman code is used, default tables can be designed with minimum penalty. parallel processing allows the coder to operate at various speeds, up to real time, and the hierarchal data structure enables operations in a progressive transmission mode. The algorithm's inherent simplicity and the use of the modulo difference operation make this coding scheme computationally simple and robust to noise and errors in coding or transmission. The system can be implemented economically in software as well as in hardware. Coder and decoder are symmetrical. Compression results can be slightly improved by using 2-D prediction but at the cost of an increase in system complexity and sensitivity to noise.

关键词： image compression image processing Visual communications parallel processing image transmission Digital imaging Telecommunications image resolution Computer programming Surgery

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HISTOGRAM EQUALIZATION UTILIZING SPATIAL CORRELATION FOR image-ENHANCEMENT

HISTOGRAM EQUALIZATION UTILIZING SPATIAL CORRELATION FOR IMA...

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CONF ON VISUAL COMMUNICATIONS AND image processing 4

作者： KAMEL, M GUAN, L Univ of Waterloo Waterloo Canada

ISBN: (纸本)0819402389

Histogram equalization (HE) techniques are widely used for image enhancement due to their simplicity and effectiveness. Most of the existing HE techniques assume image pixels to be randomly distributed over the image space. In general, adjacent image pixels are highly correlated, it is more reasonable to design HE methods that utilize this correlation. In this paper, we present a method of HE that takes spatial correlation among pixels into account. The concurrence of the gray values of adjacent pixels is calculated to form conditional probabilities of each gray level with respect to other gray levels in the image. The HE is then obtained using these probabilities. We call this method Conditional Histogram Equalization (CHE). Experimental results show that the proposed method generates images that are visually more pleasant than the ones generated by conventional HE techniques. The results also show that this method avoids the problem of over stretching the contrast in images with highly peaked histograms.

关键词： image processing

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CONCURRENT NULLSPACE methods FOR MULTIBODY SYSTEMS.

CONCURRENT NULLSPACE METHODS FOR MULTIBODY SYSTEMS.

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parallel and distributed processing in Structural Engineering, Proceedings. Presented in Conjunction with the ASCE National Convention.

作者： Kurdila, Andrew Kamat, Manohar Georgia Inst of Technology Atlanta GA USA Georgia Inst of Technology Atlanta GA USA

ISBN: (纸本)0872626407

This paper presents a new concurrent multiprocessing algorithm for simulating the dynamics of constrained multibody systems. The systems considered are quite general in nature;they may be comprised of any number of rigid and linearly elastic bodies subject to linear, nonholonomic constraints. The method is based upon the recently introduced class of algorithms that generate the nullspace of the constraints. These algorithms are comprised essentially of four computational steps: (i) the calculation of an orthonormal basis for the nullspace of the constraints and its orthogonal complement, (ii) the assembly and factorization of a system coefficient matrix, (iii) the calculation of the product of a right-inverse and a vector, and (iv) the formation and assembly of system vectors. Concurrent multiprocessing implementations of the QR decomposition, singular value decomposition and modified Gram-Schmidt technique are discussed to enable a parallel calculation of the orthonormal bases in step (i) above.

关键词： STRUCTURAL ANALYSIS

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image ALGEBRA TECHNIQUES FOR parallel image-processing

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JOURNAL OF parallel AND distributed COMPUTING 1987年第1期4卷 7-44页

作者： RITTER, GX GADER, PD UNIV FLORIDA DEPT MATHGAINESVILLEFL 32611

An image algebra has been defined which is capable of expressing a wide variety of gray-level image-to-image transformations. The purpose of this paper is fourfold: (1) to introduce the reader to the basic concepts of the image algebra; (2) to show how it suggests a general-purpose cellular pyramid array processor for real time image processing tasks; (3) to demonstrate how the image algebra can be used to formulate the problem of mapping algorithms to specific hardware; and (4) to show how algebraic techniques can be used to develop systematic methods for deriving parallel algorithms.

关键词： image processing

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MAPPING image-processing OPERATIONS ONTO A LINEAR SYSTOLIC MACHINE

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distributed COMPUTING 1986年第4期1卷 246-257页

作者： KUNG, HT WEBB, JA 1. Department of Computer Science Carnegie Mellon University 15213 Pittsburgh PA USA

A high-performance systolic machine, called Warp, is operational at Carnegie Mellon. The machine has a programmable systolic array of linearly connected cells, each capable of performing 10 million floating-point operations per second. Many image processing operations have been programmed on the machine. This programming experience has yielded new insights in the mapping of image processing operations onto a parallel computer. This paper identifies three major mapping methods that are particularly suited to a Warp-like parallel machine using a linear array of processing elements. These mapping methods correspond to partitioning of input dataset, partitioning of output dataset, and partitioning of computation along the time domain (pipelining). parallel implementations of several important image processing operations are presented to illustrate the mapping methods. These operations include the Fast Fourier transform (FFT), connected component labelling, Hough transform image warping and relaxation.

关键词： image processing Systolic arrays parallel processing Connected component labelling Hough transform image warping Relaxation

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image-ANALYSIS USING MULTIGRID RELAXATION methods

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IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 1986年第2期8卷 129-139页

作者： TERZOPOULOS, D M.I.T Artificial Intelligence Laboratory 54 Technology Square Cambridge MA 02139

image analysis problems, posed mathematically as variational principles or as partial differential equations, are amenable to numerical solution by relaxation algorithms that are local, iterative, and often parallel. Although they are well suited structurally for implementation on massively parallel, locally interconnected computational architectures, such distributed algorithms are seriously handi capped by an inherent inefficiency at propagating constraints between widely separated processing elements. Hence, they converge extremely slowly when confronted by the large representations of early vision. Application of multigrid methods can overcome this drawback, as we showed in previous work on 3-D surface reconstruction. In this paper, we develop multiresolution iterative algorithms for computing lightness, shape-from-shading, and optical flow, and we examine the efficiency of these algorithms using synthetic image inputs. The multigrid methodology that we describe is broadly applicable in early vision. Notably, it is an appealing strategy to use in conjunction with regularization analysis for the efficient solution of a wide range of ill-posed image analysis problems.

关键词： image analysis Relaxation methods Iterative algorithms Partial differential equations Concurrent computing distributed computing Computer architecture distributed algorithms Optical propagation Ultraviolet sources Author Keywords variational principles image analysis inverse problems lightness multigrid relaxation multiresolution algorithms optical flow parallel algorithms partial differential equations shape from shading

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