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International Symposium on Performance Evaluation of Computer & Telecommunication Systems SPECTS

作者： Abdelhak Attou Jie Ding D.I. Laurenson K. Moessner Centre for Communication Systems Research (CCSR) Department of Electrical and Electronics Engineering Faculty of Engineering and Physical Sciences University of Surrey Guildford UK Institute for Digital Communications Joint Research Institute for Signal & Image Processing School of Engineering and Electronics University of Edinburgh Edinburgh UK

ISBN: (纸本)9781424434497

Communication systems are becoming more complex due to the advancements and heterogeneity in device and network technologies. The diversity of content and services offered to users is increasing and services have become an important source of revenue for network operators. However, the success of service providers depends on the adaptability of their services to user environments and preferences. Hence content and service adaptation is of paramount importance. In an adaptation manager is proposed. This paper presents the performance model of the adaptation management system developed in the high level formalism PEPA, and its evaluation. The model is derived from the adaptation manager design and system interactions. The results from the evaluation are presented and analysed to determine the factors that affect system performance and how the latter can be improved.

关键词： Context-aware services Algebra Content management Performance analysis Stochastic processes Computer science Informatics Digital communication signal processing image processing

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A shared-relay cooperative diversity scheme based on joint channel and network coding

A shared-relay cooperative diversity scheme based on joint c...

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International Symposium on Information Theory and Its Applications, ISITA

作者： Xiaoyan Xu Mark F. Flanagan Christian Koller Norbert Goertz Institute for Digital Communications Joint Research Institute for Signal & Image Processing University of Edinburgh UK Department of Electronics Computer Science and Systems (DEIS) University of Bologna Italy Department of Electrical Engineering University of Notre Dame Notre Dame IN USA

ISBN: (纸本)9781424420681

In cooperative communications, the technique of algebraic code superposition (or network coding) may efficiently utilize limited communications resources to produce spatial diversity. In this paper, we propose a simple cooperative diversity scheme for the scenario of two sources sharing a single relay. No cooperative coding is required at the sources, and only very simple interleave-and-superpose operations are performed at the relay. We propose a novel computationally efficient message passing algorithm at the destination's decoder which utilizes spatial diversity gathered over multiple transmission frames. We show that despite the simplicity of the proposed scheme, diversity gains are efficiently leveraged by the simple combination of channel coding at the sources and network coding at the relay.

关键词： Network coding Decoding Relays Parity check codes Electronic mail Fading Message passing Diversity methods Information theory Digital communication

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Reduced-complexity delayed-decision algorithm for context-based image processing systems

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IEEE TRANSACTIONS ON image processing 2007年第8期16卷 1937-1945页

作者： Singh, Raghavendra Ortega, Antonio IBM India Research Laboratory New Delhi India Department of Electrical Engineering and the Signal and Image Processing Institute (SIPI) University of Southern California Los Angeles CA USA

It is well known that the performance of context-based image processing systems can be improved by allowing the processor (e.g., an encoder or denoiser) a delay several samples before making a processing decision. Often, however, for such systems, traditional delayed-decision algorithms can become computationally prohibitivev due to the growth ini the size of the space op possible solutions. In this paper, we propose a reduced-complexity, one-pass, delayed-decision algorithm that systematically reduces the size of the search space, while also preserving its structure. In particular, we apply the proposed algorithm to two examples of adaptive context-based image processing systems, an image coding system that employs a context-based entropy coder, and a spatially adaptive image-denoising system. For these two types of widely used systems, we show that the proposed delayed-decision search algorithm outperforms instanteneous-decision algorithms with only a small increase in complexity. We also show that the performance of the proposed algorithm is better than that of other, higher complexity, delayed-decision algorithms.

关键词： delayed-decision processing image coding image denoising image processing

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Performance of a self-paced brain computer interface on data contaminated with eye-movement artifacts and on data recorded in a subsequent session

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Computational Intelligence and Neuroscience 2008年第1期2008卷 749204页

作者： Fatourechi, Mehrdad Ward, Rabab K. Birch, Gary E. Image and Signal Processing Laboratory Department of Electrical and Computer Engineering University of British Columbia Vancouver BC V6T 1Z4 Canada Institute for Computing Information and Cognitive Systems University of British Columbia Vancouver BC V6T 1Z4 Canada Neil Squire Society Burnaby BC V5M 3Z3 Canada

The performance of a specific self-paced BCI (SBCI) is investigated using two different datasets to determine its suitability for using online: (1) data contaminated with large-amplitude eye movements, and (2) data recorded in a session subsequent to the original sessions used to design the system. No part of the data was rejected in the subsequent session. Therefore, this dataset can be regarded as a pseudo-online test set. The SBCI under investigation uses features extracted from three specific neurological phenomena. Each of these neurological phenomena belongs to a different frequency band. Since many prominent artifacts are either of mostly low-frequency (e.g., eye movements) or mostly high-frequency nature (e.g., muscle movements), it is expected that the system shows a fairly robust performance over artifact-contaminated data. Analysis of the data of four participants using epochs contaminated with large-amplitude eye-movement artifacts shows that the system's performance deteriorates only slightly. Furthermore, the system's performance during the session subsequent to the original sessions remained largely the same as in the original sessions for three out of the four participants. This moderate drop in performance can be considered tolerable, since allowing artifact-contaminated data to be used as inputs makes the system available for users at ALL times.

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Chesapeake bay water quality monitoring using satellite imagery

Chesapeake bay water quality monitoring using satellite imag...

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作者： Ramakrishna, Bharath Chang, Chein-I. Trou, Bruce Henqemihle, Jerry Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore County Baltimore MD 21250 Microtel LLC 111 Centerway Greenbelt MD 20770

The Chesapeake Bay is a valued ecological, economic, recreational, cultural and scenic resource. The Bay watershed States and the District of Columbia, in conjunction with the EPA Chesapeake Bay Program, have worked and teamed together over the past 20 years to protect and restore the Bay ecosystem. A key component of this effort is water quality and habitat monitoring to assess the impact of management actions and natural, processes, and evaluate habitat parameters on living resources such as submerged aquatic vegetation (SAV), oysters, and fisheries. Using aerial and satellite remote sensing imagery has become a practical and effective means of monitoring water quality in a timely manner. Of particular interest in evaluation of water clarity are several initiative measures. Specifically, Secchi-Disk Transparency (SDT) and Chlorophyll α (Chl-α) have been widely accepted as critical indicators of water quality and their reliable estimation using satellite imagery provides a cost effective and speedy means for water quality monitoring. Work done at Water Resources Center, University of Minnesota has demonstrated the feasibility of performing regional assessment of lake water quality using LANDSAT image data. This paper investigates an approach similar to their work but uses a different type of satellite imagery, EO-1 ALI imagery where the SDT and Chl-a are also used as indicators to estimate water quality for the Chesapeake Bay and DC area (Potomac River). In doing so, three major issues are investigated, which are (1) the study site that is an open Bay area, not a self-contained lake;(2) investigation of applicability of equations that are used to specify the SDT and Chl-α to our Bay area study;(3) the use of a different type of satellite imagery for water quality monitoring. This paper develops techniques to address these three issues and presents preliminary experiments which show encouraging results. © World Scientific Publishing Company.

关键词： Water quality

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Relative Iris Codes

Relative Iris Codes

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IEEE International Symposium on signal processing and Information Technology (ISSPIT)

作者： Peeranat Thoonsangngam Somying Thainimit Vutipong Areekul Kasetsart Signal and Image Processing Laboratory (KSIP Lab) Department of Electrical Engineering Faculty of Engineering Kasetsart University Bangkok Thailand

This paper proposes a new scheme to generate iris codes based on relative measure of local iris texture. The local characteristic of iris texture is analyzed using 2D Gabor wavelets. Twelve Gabor kernels, four frequencies and three orientations, are constructed and convoluted with an iris image. To inherit relationship of local iris texture among pixels, Gabor magnitude and phase of a reference pixel is compared with Gabor magnitudes and phases of the other four pixels. These pixels are located away from the reference pixel by 8×𝒹 pixels, where 𝒹=1, 2, ..., 4. Each comparison, a 2-bit primitive iris code is generated. Least significant bit of the primitive code describes how Gabor magnitudes of the two pixels are related. This bit is set to ‘1’ if Gabor magnitude of a reference pixel is less than magnitude of the other pixel, otherwise it is set to ‘0’. Another bit of the 2-bit primitive code describes relative measure of the obtained phase values. This bit is set to ‘1’if difference of the obtained phases is within ±π/2 , otherwise it is set to ‘0’. In our scheme, each pixel is described using an 8-bit iris code. Matching between two iris codes is implemented using a look-up table technique. The table contains a number of matches of the primitive code of the two iris codes. By utilizing the look-up table technique, computational time of our 1:1 matching scheme is 2.2 milliseconds. Equal-Error-Rate (EER) of the proposed system using CASIA1.0 iris database is 0.0003%EER

关键词： Iris recognition Humans signal processing image texture analysis Wavelet analysis Filters Feature extraction Table lookup Waveguide discontinuities Pattern recognition

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A Multi-Resolution Mean Field Annealing Algorithm for Motion Estimation in Medical CT image Sequences

A Multi-Resolution Mean Field Annealing Algorithm for Motion...

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International Symposium on signals, Circuits and Systems (ISSCS)

作者： Cristian Grava Vasile Buzuloiu Bertrand Augereau Christine Fernandez-Maloigne Department of Electronics Faculty of Electrical Engineering and Information Technology Oradea Romania Image Processing and Analysis Laboratory Politehnica University of Bucharest Romania Signal Image Communication Laboratory University of Poitiers France

The paper describes a multi-resolution mean field annealing (MFA) algorithm to solve the motion estimation problem in medical image sequences. The proposed algorithm ensures a satisfying trade-off between precision and computational time, in other words, it ensures a good efficiency when compared to other deterministic algorithms and also stochastic ones. The results are compared in terms of precision and computational time with those of other basic algorithms, such as the basic block-matching and Horn & Schunck algorithm. The results are illustrated on CT medical image sequences.

关键词： Annealing Motion estimation Biomedical imaging Computed tomography image sequences Stochastic processes Pixel Equations image motion analysis Laboratories

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Does an endmember set really yield maximum simplex volume?

Does an endmember set really yield maximum simplex volume?

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Chao-Cheng Wu Chein-I Chang Remote Sensing Signal and Image Processing Laboratory the Department of Computer Science and Electrical Engineering Department University of Maryland Baltimore MD USA

One of commonly used criteria for finding an endmember set is to assume that for a given number of endmembers, p, a p-vertex simplex with its vertices specified by p endmembers always yields the maximum volume. Since there are also other criteria which have been widely used for endmember extraction, the issue of interest is "does an endmember set really produce a simplex with maximum volume?" In other words, using the criterion of a simplex with maximum volume is a better and more effective measure than other criteria currently being used by endmember extraction such as orthogonal projection-based pixel purity index (PPI), fully constrained least squares-based spectral unmixing, etc. This paper explores this issue by investigating a number of popular endmember extraction algorithms which are designed by different criteria. An extensive experiment-based study is also conducted for comparative analysis.

关键词： Algorithm design and analysis Least squares methods Hyperspectral imaging Indexes Volume measurement Chaos Data mining Subspace constraints Computational efficiency Current measurement

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IHS and support value integrated approach to improve pansharpening quality of QuickBird image

IHS and support value integrated approach to improve panshar...

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MIPPR 2007: Multispectral image processing

作者： Zheng, Sheng Yang, Changeai Liu, Jian Tian, Jinwen Electronics and Information Engineering Department Huazhong University of Science and Technology Wuhan 430074 China Institute of Intelligent Vision and Image Information Best College of Electrical Engineering and Information Technology China Three Gorges University Yichang 443002 China State Education Commission Key Laboratory for Image Processing and Intelligent Control Huazhong University of Science and Technology Wuhan 430074 China

ISBN: (纸本)9780819469519

image fusion is an important tool in remote sensing, since many Earth observation satellites provide both high-resolution panchromatic (Pan) and low-resolution multispectral (MS) images. To date, many image fusion techniques have been developed. However, the available algorithms can hardly produce a satisfactory fusion result for IKONOS and QuickBird images. Among the existing fusion algorithms, the IHS technique is the most widely used one, and the wavelet fusion is the most frequently discussed one in recent publications because of its advantages over other fusion techniques. But the color distortion of these two techniques is often obvious. The support value fusion technique demonstrates some advantages over the conventional methods. This study presents a new fusion approach that integrates the advantages of both the IHS and the support value techniques to reduce the color distortion of QuickBird fusion results. Different QuickBird images have been fused with this new approach. Visual and statistical analyses prove that the concept of the proposed extended fast IHS (eFIHS) and support value integration is promising, and it does significantly improve the fusion quality compared to conventional IHS (eFIHS) and wavelet fusion techniques.

关键词： image fusion

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Opportunistic Access with Random Subchannel Backoff (OARSB) for OFDMA Uplink

Opportunistic Access with Random Subchannel Backoff (OARSB) ...

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IEEE GLOBECOM 2007 - IEEE Global Telecommunications Conference

作者： Yu-Jung Chang Feng-Tsun Chien C.-C. Jay Kuo Ming Hsieh Department of Electrical Engineering and Signal and Image Processing Institute University of Southern California Los Angeles CA USA Department of Electronics Engineering National Chiao Tung University Taiwan

A distributed medium access control (MAC) algorithm for uplink OFDMA networks under the IEEE 802.16 framework is proposed and analyzed in this work. We present a simple yet efficient algorithm to enhance the system throughput by integrating opportunistic medium access and collision resolution through random subchannel backoff. Consequently, the resulting algorithm is called the opportunistic access with random subchannel backoff (OARSB) scheme. OARSB not only achieves distributed coordination among users but also reduces the amount of information exchange between the base station and users. The throughput and delay performance analysis of OARSB is conducted using a Markov chain model. The superior performance of OARSB over an existing scheme is demonstrated by analysis as well as computer simulation.

关键词： Throughput Base stations Downlink Bandwidth Performance analysis Channel allocation Switches signal processing image processing USA Councils

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