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New accelerated graph-based method of image segmentation applying minimum spanning tree

IET image processing 2014年第4期8卷 239-251页

作者： Fabijanska, Anna Goclawski, Jaroslaw Lodz Univ Technol Inst Appl Comp Sci Lodz Poland

In this paper problem of graph based image segmentation is considered. In particular, attention is paid to minimal spanning tree based algorithm proposed by Felzenszwalb and Huttenlocher (FH). Although the method yields high quality results for various classes of images, its application is limited mainly to off-line processing. Its due to the very long execution time of the FH method, which in the case of high resolution images, requires processing of millions of vertices and edges contained within the resulting graph. Therefore, some improvements to the FH method are proposed in this paper. The modifications aim at the reduction of algorithm execution time and the usage of computer host memory. These goals are achieved both by reducing the size of input image graph and by applying the methods of GPU parallel computing at initial stages of the algorithm. As the reduction of graph size is obtained by processing meta-pixels representing homogenous regions, the new method is most suitable for the segmentation of images including rare, structurally complex objects distributed over nonuniform background. Results obtained by the introduced approach are compared with the results of the original FH method and other popular graph-based approaches to image segmentation. The comparison includes both the accuracy of image segmentation and the execution time. Analysis of the results clearly shows, that the proposed approach in many cases can significantly accelerate segmentation process without a noticeable loss of image segmentation quality.

关键词： graph theory image segmentation trees (mathematics) image segmentation minimum tree accelerated graph-based method FH algorithm Felzenszwalb and Huttenlocher algorithm

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Oscillatory Neural Networks: In Problems of parallel Information processing

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2014年

作者： Margarita G. Kuzmina Eduard A. Manykin Evgeny S. Grichuk

ISBN: (数字)9783110269208

ISBN: (纸本)9783110268355

Understanding of the human brain functioning currently represents a challenging problem. In contrast to usual serial computers and complicated hierarchically organized artificial man-made systems, decentralized, parallel and distributed information processing principles are inherent to the brain. Besides adaptation and learning, which play a crucial role in brain functioning, oscillatory neural activity, synchronization and resonance accompany the brain work. Neural-like oscillatory network models, designed by the authors for image processing, allow to elucidate the capabilities of dynamical, synchronization-based types of image processing, presumably exploited by the brain. The oscillatory network models, studied by means of computer modeling and qualitative analysis, are presented and discussed in the book. Some other problems of parallel distributed information processing are also considered, such as a recall process from network memory for large-scale recurrent associative memory neural networks, performance of oscillatory networks of associative memory, dynamical oscillatory network methods of image processing with synchronization-based performance, optical parallel information processing based on the nonlinear optical phenomenon of photon echo, and modeling random electric fields of quasi-monochromatic polarized light beams using systems of superposed stochastic oscillators. This makes the book highly interesting to researchers dealing with various aspects of parallel information processing.

关键词： Human information processing. Neural networks (Neurobiology)

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Using local utility maximization to detect social networks communities

Using local utility maximization to detect social networks c...

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CSI International Symposium on Computer Science and Software Engineering (CSSE)

作者： Ardavan Afshar Bahareh Ashenagar Negar Foroutan Eghlidi Mansour Zolghadri Jahromi Ali Hamzeh Department of Computer Science and Engineering & IT Shiraz University Shiraz Iran Shiraz University Shiraz Fars IR

ISBN: (纸本)9781467391825

Community detection has recently turned to be one of the most popular research topics in social networks analysis. Majority of community detection methods already considered in the literature try to optimize a global metric through a centralized decision maker. These approaches are too time-consuming in huge networks. Several of methods need initial parameters such as number and size of communities in order to find out the problems; however, they are not always reachable. In this paper, we propose a local utility maximization approach for community identification as a distributed framework in which each community acts as a selfish agent to maximize its utility function based on some predefined actions. Our framework has some crucial characteristic features. The first feature is the local approach that is easily implemented through parallel computing concepts, while the second is an economical interpretation of utility measurement. Experimental results on output benchmark datasets show that our proposed method can perform as well as the existing centralized approaches that already exist in the literature to detect non-overlapping communities.

关键词： Social network services Measurement image edge detection Symmetric matrices Eigenvalues and eigenfunctions Computer science parallel processing

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SU-C-207A-06: On-Line Beam Range Verification with Multiple Scanning Particle Beams: Initial Feasibility Study with Simulations

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Medical Physics 2016年第6PART3期43卷 3325-3325页

作者： Y Zhong X Sun W Lu X Jia J Wang Y Shao The University of Texas Southwestern Medical Ctr. Dallas TX

Purpose: To investigate the feasibility and requirement for intra-fraction on-line multiple scanning particle beam range verifications (BRVs) with in-situ PET imaging, which is beyond the current single-beam BRV with extra factors that will affect the BR measurement accuracy, such as beam diameter, separation between beams, and different image counts at different BRV positions. methods: We simulated a 110-MeV proton beam with 5-mm diameter irradiating a uniform PMMA phantom by GATE simulation, which generated nuclear interaction-induced positrons. In this preliminary study, we simply duplicated these positrons and placed them next to the initial protons to approximately mimic the two spatially separated positron distributions produced by two beams parallel to each other but with different beam ranges. These positrons were then imaged by a PET (∼2-mm resolution, 10% sensitivity, 320×320×128 mm^3 FOV) with different acquisition times. We calculated the positron activity ranges (ARs) from reconstructed PET images and compared them with the corresponding ARs of original positron distributions. Results: Without further image data processing and correction, the preliminary study show the errors between the measured and original ARs varied from 0.2 mm to 2.3 mm as center-to-center separations and range differences were in the range of 8–12 mm and 2–8 mm respectively, indicating the accuracy of AR measurement strongly depends on the beam separations and range differences. In addition, it is feasible to achieve ≤ 1.0-mm accuracy for both beams with 1-min PET acquisition and 12 mm beam separation. Conclusion: This study shows that the overlap between the positron distributions from multiple scanning beams can significantly impact the accuracy of BRVs of distributed particle beams and need to be further addressed beyond the established method of single-beam BRV, but it also indicates the feasibility to achieve accurate on-line multi-beam BRV with further improved method.

关键词： Positron beams Positrons Positron emission tomography image reconstruction Protons Electric measurements Spatial dimensions Nuclear interactions Data processing

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The framework of P systems applied to solve optimal watermarking problem

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SIGNAL processing 2014年 101卷 256-265页

作者： Peng, Hong Wang, Jun Perez-Jimenez, Mario J. Riscos-Nunez, Agustin Xihua Univ Ctr Radio Adm & Technol Dev Chengdu 610039 Peoples R China Xihua Univ Sch Elect & Informat Engn Chengdu 610039 Peoples R China Univ Seville Dept Comp Sci & Artificial Intelligence Res Grp Nat Comp E-41012 Seville Spain

Membrane computing (known as P systems) is a novel class of distributed parallel computing models inspired by the structure and functioning of living cells and organs, and its application to the real-world problems has become a hot topic in recent years. This paper discusses an interesting open problem in digital watermarking domain, optimal watermarking problem, and proposes a new optimal image watermarking method under the framework of P systems. A special membrane structure is designed and its cells as parallel computing units are used to find the optimal watermarking parameters for image blocks. Some cells use the position-velocity model to evolve watermarking parameters of image blocks, while another cell evaluates the objects in the system. In addition to the evolution rules, communication rules are used to exchange and share information between the cells. Simulation experiments on large image set compare the proposed framework with other existing watermarking methods and demonstrate its superiority. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Membrane computing P systems image watermarking Optimal watermarking problem

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Evaluation of a Sector-Hash Based Rapid File Detection Method for Monitoring Infrastructure-as-a-Service Cloud Platforms

Evaluation of a Sector-Hash Based Rapid File Detection Metho...

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International Conference on Availability, Reliability and Security, ARES

作者： Manabu Hirano Hayate Takase Koki Yoshida Department of Information and Computer Engineering National Institute of Technology Japan

Current computer forensics tools have some limitations on anti-forensics attacks, cloud computing, and a large increase in the size of forensics targets. To solve these problems, this paper proposes a system that preserves storage data on virtual machines by acquiring all data sectors with time stamps. The proposed system can restore a previous state of a block device at any date and time that is specified by an investigator. The proposed system aims to monitor users' behavior in Infrastructure-as-a-Service (IaaS) cloud platforms. This paper also presents a rapid file detection system that finds a target file from a large collection of the acquired data sectors by using sector-hashes and parallel distributed processing. This system enables investigators to track and to find a target file that is related to incidents or crimes in the cloud. First, this paper reports the preliminary experiments of a sector-hash based file detection method on three major operating systems for evaluating its effectiveness. We present a design and an implementation of the proposed monitoring and target file detection system by using Xen hypervisor and MapReduce. We report results of its performance evaluation. Finally, we discuss possible methods to improve the performance and the limitations of the current proposed mechanism.

关键词： Forensics Computers Monitoring image restoration distributed databases File systems Cloud computing

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A Comparative Study on Interpolation methods in Rebinning Circular Fan-beam data into parallel-beam data

A Comparative Study on Interpolation Methods in Rebinning Ci...

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27th IEEE International Symposium on Computer-Based Medical Systems (CBMS)

作者： Ryu, Sunsik Back, Jongduk Yonsei Univ Yonsei Inst Convergence Technol Inchon South Korea

ISBN: (纸本)9781479944354

Computed Tomography (CT) scanners evolved from simple parallel-beam geometry into more complex fan-beam geometry. The rebinning mechanism to convert fan-beam projections to parallel-beam projections is one of the methods simplifying the reconstruction of the CT image. Various interpolation methods result in different numerical presentations and noisy textures in the reconstructed CT images. This paper evaluates three interpolation methods, linear, frequency domain and higher order in rebinning fan-beam data into parallel-beam data in the framework of the FBP algorithm in parallel-beam CTs. The high-contrast spatial resolution, modulation transfer function (MTF), and noise are used to quantify the image quality. The noise is expressed as the noise power spectrum (NPS) and noise variance of the reconstructed image containing only Poisson distributed noise. Our results show that the higher order interpolation, cubic-spline, is the most helpful to improve the image quality in rebinning. We further demonstrate that the rebinning data gives more satisfactory results for assessment of noise variance in comparison with the fan-beam data.

关键词： image processing x-ray CT rebinning MTF interpolation

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Towards a performance-portable description of geometric multigrid algorithms using a domain-specific language

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JOURNAL OF parallel AND distributed COMPUTING 2014年第12期74卷 3191-3201页

作者： Membarth, Richard Reiche, Oliver Schmitt, Christian Hannig, Frank Teich, Juergen Stuermer, Markus Koestler, Harald German Res Ctr Artificial Intelligence Saarbrucken Germany Univ Saarland Comp Graph Lab D-66123 Saarbrucken Germany Univ Saarland Intel Visual Comp Inst D-66123 Saarbrucken Germany Univ Erlangen Nurnberg Dept Comp Sci Nurnberg Germany

High Performance Computing (HPC) systems are nowadays more and more heterogeneous. Different processor types can be found on a single node including accelerators such as Graphics processing Units (GPUs). To cope with the challenge of programming such complex systems, this work presents a domain-specific approach to automatically generate code tailored to different processor types. Low-level CUDA and OpenCL code is generated from a high-level description of an algorithm specified in a Domain-Specific Language (DSL) instead of writing hand-tuned code for GPU accelerators. The DSL is part of the Heterogeneous image processing Acceleration (HIPA(cc)) framework and was extended in this work to handle grid hierarchies in order to model different cycle types. Language constructs are introduced to process and represent data at different resolutions. This allows to describe image processing algorithms that work on image pyramids as well as multigrid methods in the stencil domain. By decoupling the algorithm from its schedule, the proposed approach allows to generate efficient stencil code implementations. Our results show that similar performance compared to hand-tuned codes can be achieved. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Multigrid Multiresolution image pyramid Domain-specific language Stencil codes Code generation GPU CUDA OpenCL

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基于FPGA的数字化眼科超声成像中信号处理算法的研究与实现

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中国医疗器械杂志 2015年第1期39卷 1-4页

作者：方思敏周盛王晓春叶青盛田玲计建军王延群北京协和医学院中国医学科学院生物医学工程研究所天津市300192 天津市眼科医学设备技术工程中心天津市300384

目的基于FPGA对眼科超声诊断仪中的信号处理算法进行设计和改进。方法在Quartus II中用Verilog HDL硬件语言实现全并行分布式动态滤波、数字正交检波、二叉树法对数压缩三大信号处理模块。结果相对原有系统,硬件开销减少,整体成像更为清... 详细信息

目的基于FPGA对眼科超声诊断仪中的信号处理算法进行设计和改进。方法在Quartus II中用Verilog HDL硬件语言实现全并行分布式动态滤波、数字正交检波、二叉树法对数压缩三大信号处理模块。结果相对原有系统,硬件开销减少,整体成像更为清晰,眼球深部的信息更为完整,探测深度由原来的5 cm提高到6 cm。结论所设计的算法达到了设计要求,能够有效提高现有设备的成像质量,实现了系统优化。

关键词：眼科超声数字信号处理动态滤波正交检波对数压缩

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EFFICIENT RENDERING OF COMPLEX SCENES ON HETEROGENEOUS parallel ARCHITECTURES

EFFICIENT RENDERING OF COMPLEX SCENES ON HETEROGENEOUS PARAL...

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作者： GOKCE YILDIRIM KALKAN Middle East Technical University

学位级别：博士

In computer graphics, generating high-quality images at high frame rates for render- ing complex scenes is a challenging task. A well-known approach to tackling this important task is to utilize parallel processing through distributing rendering and sim- ulation tasks to different processing units. In this thesis, several methods of distributed rendering architectures are investigated, and the bottlenecks in distributed rendering are analyzed. Based on this analysis, guidelines for distributed rendering in a network of computers are proposed. Moreover, in the thesis, an efficient load balancing strategy is proposed for distribut- ing the rendering of individual frames to different processing units in a network. In this distributed rendering heterogeneous system, there are computers equipped with multiple Graphical processing Units (GPUs) with different rendering performances all in the same network with a server, which collects rendering performances of the GPUs in the different image Generators (IGs) based on an effective load balancing. By means of the novel load balancing strategy, the thesis shows that such a system can increase the rendering performance of slow computers with the help of the fast ones. Lastly, this model is extended to develop an adaptive hybrid model where (i) parts of a frame or a scene can be distributed and (ii) GPU-GPU and GPU-CPU distributions can be considered. This model can adjust itself to the changing loads of the GPUs and determine an efficient load balancing strategy for distributed rendering.

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