Parallel partitioning for distributed systems using sequential assignment

This paper introduces a method to combine the advantages of both task parallelism and fine-grained co-design specialisation to achieve faster execution times than either method alone on distributed heterogeneous architectures. The method uses a novel mixed integer linear programming formalisation to assign code sections from parallel tasks to share computational components with the optimal trade-off between acceleration from component specialism and serialisation delay. The paper provides results for software benchmarks partitioned using the method and formal implementations of previous alternatives to demonstrate both the practical tractability of the linear programming approach and the increase in program acceleration potential deliverable.     

Commercial digital image libraries,digital images and digital discontent

Publications such as consumer magazines rely heavily on image libraries as sources for the images they use in their issues. Traditionally, magazine editorial staff have discussed their image requirements over the telephone with library staff and the library has conducted the search. Many libraries have now developed Web sites and their customers search them for images themselves. A minority have e-commerce capabilities, and enable customers to purchase and download digital images from their sites. This survey found that magazine staff do not often choose to search digital libraries, preferring instead to continue to contact the library by telephone. Most also choose not to buy the use of digital images, but prefer to continue to work with conventional transparencies and slides. The reasons for these preferences, and the reasons they are unlikely to change in the short term, are explored.     

序列模式挖掘的并行算法研究

序列模式在许多领域都有着重要的应用,大量的数据和模式需要高效的、可扩展的并行算法.针对目前序列模式挖掘算法存在的普遍问题,提出了一个适合无共享并行环境下的算法PMSP,有效地解决了存储受限以及时效性问题,并将它与当前相对较优的并行算法HPSPM做了比较,实验表明PMSP是有效的.     

A nonparametric-test-based structural similarity measure for digital images

In image processing, image similarity indices evaluate how much structural information is maintained by a processed image in relation to a reference image. Commonly used measures, such as the mean squared error (MSE) and peak signal to noise ratio (PSNR), ignore the spatial information (e.g. redundancy) contained in natural images, which can lead to an inconsistent similarity evaluation from the human visual perception. Recently, a structural similarity measure (SSIM), that quantifies image fidelity through estimation of local correlations scaled by local brightness and contrast comparisons, was introduced by Wang et al. (2004). This correlation-based SSIM outperforms MSE in the similarity assessment of natural images. However, as correlation only measures linear dependence, distortions from multiple sources or nonlinear image processing such as nonlinear filtering can cause SSIM to under- or overestimate the true structural similarity. In this article, we propose a new similarity measure that replaces the correlation and contrast comparisons of SSIM by a term obtained from a nonparametric test that has superior power to capture general dependence, including linear and nonlinear dependence in the conditional mean regression function as a special case. The new similarity measure applied to images from noise contamination, filtering, and watermarking, provides a more consistent image structural fidelity measure than commonly used measures.     

Computing distance transformations in convex and non-convex domains

It is shown that the well known two-pass sequential local transformation algorithm for computing a distance transformation in rectangular domains may fail in some convex integer domains, but that a four-pass algorithm is sufficient in all two-dimensional convex domains. For non-convex domains the number of passes necessary is shown to be generally greater. Two propagation algorithms for computing the distance transformation are described and shown theoretically and experimentally to be computationally more efficient than the sequential local transformation algorithm in non-convex domains of complex shape. The relationship of the distance transformation in non-convex domains to some more general transformations is explored.     

序列关联并行挖掘算法研究

Ming sequential associations is becoming increasing essential in many scientific and commercial domains Developing parallel algorithm becomes quite challenging depending on enormous size of available dataset and possibly large number of mined associations ,the nature of input data and the timing constraints imposed on the desired associa-tions. In this paper , we discuss several different parallel algorithms that cater to various situations to speed up thecurrent mining process.     

Connectivity-preserving transformations of binary images

A binary image I is B_a, W_b-connected, where a, b ∈ {4, 8}, if its foreground is a-connected and its background is b-connected. We consider a local modification of a B_a, w_b-connected image I in which a black pixel can be interchanged with an adjacent white pixel provided that this preserves the connectivity of both the foreground and the background of I. We have shown that for any (a, b) ∈ {(4, 8), (8, 4), (8, 8)}, any two B_a, w_b-connected images I and J each with n black pixels differ by a sequence of Θ(n²) interchanges. We have also shown that any two B₄, W₄-connected images I and J each with n black pixels differ by a sequence of O(n⁴) interchanges.     

A forgery detection algorithm for exemplar-based inpainting images using multi-region relation

The identification of image authenticity has received much attention because of the increasing power of image editing methods. This paper proposes a novel forgery detection algorithm to recognize tampered inpainting images, which is one of the effective approaches for image manipulation. The proposed algorithm contains two major processes: suspicious region detection and forged region identification. Suspicious region detection searches the similarity blocks in an image to find the suspicious regions and uses a similarity vector field to remove the false positives caused by uniform area. Forged region identification applies a new method, multi-region relation (MRR), to identify the forged regions from the suspicious regions. The proposed approach can effectively recognize if an image is a forged one and identify the forged regions, even for the images containing the uniform background. Moreover, we propose a two-stage searching algorithm based on weight transformation to speed up the computation speed. The experimental results show that the proposed approach has good performance with fast speed under different kinds of inpainting images.     

Scalable edge enhancement with automatic optimization for digital radiographic images

The ability to resolve fine picture detail is of paramount importance in medical imaging systems for viewing small tissue, bone structure and anatomy in X-ray images. In this paper, we present a new digital radiographic image processing system with the property of scalability and adaptability. (i) A new automatic optimization algorithm is proposed for display. (ii) An adaptive detection of a region-of-interest is developed. (iii) A “scalable edge enhancement algorithm” is proposed to improve the image quality for showing subtle structures in digital radiographic images. The advantage of the proposed method is demonstrated through experiments on 200 digital X-ray images and 50 CT images, in which different parts of human body structures are captured.     

Strategies for designing geometric transformations on quantum images

Three design strategies for constructing new geometric transformations on quantum images from other transformations are proposed. The strategies focus on the affected areas in the images, the separability, and smoothness of the transformations by exploiting a representation of images on quantum computers extensively. The complexity in terms of the number of basic gates and the depth of the corresponding circuits are analyzed to understand the advantages and disadvantages of each strategy. Examples to demonstrate the applicability of the proposed strategies are presented. The strategies provide high level tools to explore and analyze transformations which are necessary to build practical image processing applications on quantum computers.     

Understanding digital transformation: A review and a research agenda

Extant literature has increased our understanding of specific aspects of digital transformation, however we lack a comprehensive portrait of its nature and implications. Through a review of 282 works, we inductively build a framework of digital transformation articulated across eight building blocks. Our framework foregrounds digital transformation as a process where digital technologies create disruptions triggering strategic responses from organizations that seek to alter their value creation paths while managing the structural changes and organizational barriers that affect the positive and negative outcomes of this process. Building on this framework, we elaborate a research agenda that proposes [1] examining the role of dynamic capabilities, and [2] accounting for ethical issues as important avenues for future strategic IS research on digital transformation.     

Parallel,overlapped, and intersected digital straight lines

A digital straight line is represented by a chain code of directions which satisfy Freeman's three criteria. Given two chain codes of digital straight lines and their starting pixels where their equations are not known, the paper will describe how to determine if they are parallel, overlapped, or intersected. An algorithm with only integer arithmetic is also implemented to find the intersection.     

Personal authentication using digital retinal images

Traditional authentication (identity verification) systems, used to gain access to a private area in a building or to data stored in a computer, are based on something the user has (an authentication card, a magnetic key) or something the user knows (a password, an identification code). However, emerging technologies allow for more reliable and comfortable user authentication methods, most of them based on biometric parameters. Much work could be found in the literature about biometric-based authentication, using parameters like iris, voice, fingerprints, face characteristics, and others. In this work a novel authentication method is presented and preliminary results are shown. The biometric parameter employed for the authentication is the retinal vessel tree, acquired through retinal digital images, i.e., photographs of the fundus of the eye. It has already been asserted by expert clinicians that the configuration of the retinal vessels is unique for each individual and that it does not vary during his life, so it is a very well-suited identification characteristic. Before the verification process can be executed, a registration step is required to align both the reference image and the picture to be verified. A fast and reliable registration method is used to perform this step, so that the whole authentication process takes about 0.3 s.     

Computing convexity properties of images on a pyramid computer

We present efficient parallel algorithms for using a pyramid computer to determine convexity properties of digitized black/white pictures and labeled figures. Algorithms are presented for deciding convexity, identifying extreme points of convex hulls, and using extreme points in a variety of fashions. For a pyramid computer with a base ofn simple processing elements arranged in ann ^1/2 ×n ^1/2 square, the running times of the algorithms range from (logn) to find the extreme points of a convex figure in a digitized picture, to (n ^1/6) to find the diameter of a labeled figure, (n ^1/4 logn) to find the extreme points of every figure in a digitized picture, to (n ^1/2) to find the extreme points of every labeled set of processing elements. Our results show that the pyramid computer can be used to obtain efficient solutions to nontrivial problems in image analysis. We also show the sensitivity of efficient pyramid-computer algorithms to the rate at which essential data can be compressed. Finally, we show that a wide variety of techniques are needed to make full and efficient use of the pyramid architecture.This research was partially supported by National Science Foundation Grants MCS-83-01019, DCR-8507851, DCR-8608640, IRI-8800514 and an Incentives for Excellence Award from the Digital Equipment Corporation.     

Parallel distance transforms on a linear array architecture

Distance transformation (DT) has been widely used for image matching and shape analysis. In this paper, a parallel algorithm for computing distance transformation is presented. First, it is shown that the algorithm has an execution time of 6N−4 cycles, for an N×N image using a parallel architecture that requires ⌈N/2⌉ parallel processors. By doing so, the real time requirement is fulfilled and its execution time is independent of the image contents. In addition, a partition method is developed to process an image when the parallel architecture has a fixed number of processing elements (PEs); say two or more. The total execution time for an N×N image by employing a fixed number of PEs is 2[N²/M+2(M−1)], when M is the fixed number of PEs.     

基于伪MMX技术的并行识别算法及其应用

本文提出了一种通用的并行算法模型。这种模型可以适用于许多多数据块处理系统。该算法可以成倍提高系统的处理速度。算法的核心采用了伪MMX技术,对机器硬件没有特殊要求,保证了程序的可移植性。本文对此做了详细论述。同时本文还讨论了该算法模型在余弦整形变换系统上的实现,其处理速度较原算法有了成倍提高。     

A rigorous sequential update strategy for parallel kinetic Monte Carlo simulation

The kinetic Monte Carlo (kMC) method is used in many scientific fields in applications involving rare-event transitions. Due to its discrete stochastic nature, efforts to parallelize kMC approaches often produce unbalanced time evolutions requiring complex implementations to ensure correct statistics. In the context of parallel kMC, the sequential update technique has shown promise by generating high quality distributions with high relative efficiencies for short-range systems. In this work, we provide an extension of the sequential update method in a parallel context that rigorously obeys detailed balance, which guarantees exact equilibrium statistics for all parallelization settings. Our approach also preserves nonequilibrium dynamics with minimal error for many parallelization settings, and can be used to achieve highly precise sampling.     

A fusion-based approach to digital movie restoration

Many algorithms have been proposed in literature for digital movie restoration; unfortunately, none of them ensures a perfect result whichever is the image sequence to be restored. Here we propose a new digital scratch restoration algorithm which achieves accuracy results higher than that of already existing algorithms and naturally adapts for implementation into high-performance computing environments.The basic idea of the proposed algorithm is to adopt several relatively well-settled algorithms for the problem at hand and combine obtained results through suitable image fusion techniques, with the aim of taking advantage of the adopted algorithms’ capabilities and, at the same time, limiting their deficiencies.Extensive experiments on real image sequences deeply investigate both accuracy results of the presented scratch restoration approach, which is shown to outperform other existing approaches, and performance of its parallel implementation, which allows for real-time restoration.     

Comparing digital implementation via the bilinear and step-invariant transformations

From an analog system K, digital systems K_d and K_bt are often obtained via the step-invariant and bilinear transformations, respectively. For the case when K is stable, it is shown that under certain conditions, K_bt converges to K_d in ?_p-induced norms as the sampling period tends to zero for 1?p?∞. Furthermore, K_bt converges to K_d in the graph metric as the sampling period tends to zero no matter whether K is stable or not.     

大规模并行计算机系统并行性能模拟技术研究

性能模拟技术是计算机系统性能评价的重要手段.介绍了面向大规模并行计算机系统以及消息传递应用程序的并行性能模拟技术,总结了相关的关键技术和国内外研究现状.对几个代表性的并行模拟器系统进行了详细介绍.结合并行计算机系统和应用的发展趋势,讨论了未来并行模拟器设计、实现面临的问题和可能的解决方案.