TY - CONF T1 - Component-based restoration of speckled images T2 - 2011 18th IEEE International Conference on Image Processing (ICIP) Y1 - 2011 A1 - Patel, Vishal M. A1 - Easley,G. R A1 - Chellapa, Rama KW - coherent imaging modalities KW - component optimization formulation KW - component-based restoration KW - Dictionaries KW - image restoration KW - iterative algorithm KW - iterative methods KW - multiplicative noise KW - NOISE KW - optimisation KW - radar imaging KW - SAR images KW - Speckle KW - speckle reduction algorithm KW - speckled images KW - structure components KW - surrogate functionals KW - synthetic aperture radar KW - texture components KW - transforms KW - TV AB - Many coherent imaging modalities are often characterized by a multiplicative noise, known as speckle which often makes the interpretation of data difficult. In this paper, we present a speckle reduction algorithm based on separating the structure and texture components of SAR images. An iterative algorithm based on surrogate functionals is presented that solves the component optimization formulation. Experiments indicate this proposed method performs favorably compared to state-of-the-art speckle reduction methods. JA - 2011 18th IEEE International Conference on Image Processing (ICIP) PB - IEEE SN - 978-1-4577-1304-0 M3 - 10.1109/ICIP.2011.6116252 ER - TY - CONF T1 - The Life Game: Cognitive Strategies for Repeated Stochastic Games Y1 - 2011 A1 - Cheng,Kan-Leung A1 - Zuckerman,I. A1 - Nau, Dana S. A1 - Golbeck,J. KW - adaptive model KW - behavioral strategy KW - bioevolutionary game theory KW - cognitive agent model KW - fine-grained opponent model KW - game theory KW - iteration KW - iterative methods KW - life game KW - prisoner's dilemma KW - repeated stochastic games KW - social value orientation theory KW - stag hunt KW - stage game KW - Stochastic processes KW - trust behavior AB - Standard models in bio-evolutionary game theory involve repetitions of a single stage game (e.g., the Prisoner's Dilemma or the Stag Hunt); but it is clear that repeatedly playing the same stage game is not an accurate model of most individuals' lives. Rather, individuals' interactions with others correspond to many different kinds of stage games. In this work, we concentrate on discovering behavioral strategies that are successful for the life game, in which the stage game is chosen stochastically at each iteration. We present a cognitive agent model based on Social Value Orientation (SVO) theory. We provide extensive evaluations of our model's performance, both against standard agents from the game theory literature and against a large set of life-game agents written by students in two different countries. Our empirical results suggest that for life-game strategies to be successful in environments with such agents, it is important (i) to be unforgiving with respect to trust behavior and (ii) to use adaptive, fine-grained opponent models of the other agents. M3 - 10.1109/PASSAT/SocialCom.2011.62 ER - TY - JOUR T1 - A broadband fast multipole accelerated boundary element method for the three dimensional Helmholtz equation JF - The Journal of the Acoustical Society of America Y1 - 2009 A1 - Gumerov, Nail A. A1 - Duraiswami, Ramani KW - acoustic wave scattering KW - boundary-elements methods KW - boundary-value problems KW - Helmholtz equations KW - iterative methods AB - The development of a fast multipole method (FMM) accelerated iterative solution of the boundary element method (BEM) for the Helmholtz equations in three dimensions is described. The FMM for the Helmholtz equation is significantly different for problems with low and high kD (where k is the wavenumber and D the domain size), and for large problems the method must be switched between levels of the hierarchy. The BEM requires several approximate computations (numerical quadrature, approximations of the boundary shapes using elements), and these errors must be balanced against approximations introduced by the FMM and the convergence criterion for iterative solution. These different errors must all be chosen in a way that, on the one hand, excess work is not done and, on the other, that the error achieved by the overall computation is acceptable. Details of translation operators for low and high kD, choice of representations, and BEM quadrature schemes, all consistent with these approximations, are described. A novel preconditioner using a low accuracy FMM accelerated solver as a right preconditioner is also described. Results of the developed solvers for large boundary value problems with 0.0001≲kD≲500 are presented and shown to perform close to theoretical expectations. VL - 125 UR - http://link.aip.org/link/?JAS/125/191/1 CP - 1 M3 - 10.1121/1.3021297 ER - TY - JOUR T1 - Robust Wavelet-Based Super-Resolution Reconstruction: Theory and Algorithm JF - IEEE Transactions on Pattern Analysis and Machine Intelligence Y1 - 2009 A1 - Hui Ji A1 - Fermüller, Cornelia KW - batch algorithm KW - better-conditioned iterative back projection scheme KW - Enhancement KW - homography estimation KW - image denoising KW - image denoising scheme KW - image frame alignment KW - Image processing software KW - Image reconstruction KW - image resolution KW - image sequence KW - Image sequences KW - iterative methods KW - regularization criteria KW - robust wavelet-based iterative super-resolution reconstruction KW - surface normal vector KW - video formation analysis KW - video sequence KW - video signal processing KW - Wavelet transforms AB - We present an analysis and algorithm for the problem of super-resolution imaging, that is the reconstruction of HR (high-resolution) images from a sequence of LR (low-resolution) images. Super-resolution reconstruction entails solutions to two problems. One is the alignment of image frames. The other is the reconstruction of a HR image from multiple aligned LR images. Both are important for the performance of super-resolution imaging. Image alignment is addressed with a new batch algorithm, which simultaneously estimates the homographies between multiple image frames by enforcing the surface normal vectors to be the same. This approach can handle longer video sequences quite well. Reconstruction is addressed with a wavelet-based iterative reconstruction algorithm with an efficient de-noising scheme. The technique is based on a new analysis of video formation. At a high level our method could be described as a better-conditioned iterative back projection scheme with an efficient regularization criteria in each iteration step. Experiments with both simulated and real data demonstrate that our approach has better performance than existing super-resolution methods. It can remove even large amounts of mixed noise without creating artifacts. VL - 31 SN - 0162-8828 CP - 4 M3 - 10.1109/TPAMI.2008.103 ER - TY - CONF T1 - Efficient Kriging via Fast Matrix-Vector Products T2 - Aerospace Conference, 2008 IEEE Y1 - 2008 A1 - Memarsadeghi,N. A1 - Raykar,V.C. A1 - Duraiswami, Ramani A1 - Mount, Dave KW - cokriging technique KW - fast matrix-vector products KW - fast multipole methods KW - geophysical techniques KW - image fusion KW - Interpolation KW - iterative methods KW - nearest neighbor searching KW - optimal scattered data estimator KW - Remote sensing KW - remotely sensed data KW - scattered data points KW - sensor fusion KW - time efficiency AB - Interpolating scattered data points is a problem of wide ranging interest. Ordinary kriging is an optimal scattered data estimator, widely used in geosciences and remote sensing. A generalized version of this technique, called cokriging, can be used for image fusion of remotely sensed data. However, it is computationally very expensive for large data sets. We demonstrate the time efficiency and accuracy of approximating ordinary kriging through the use of fast matrix-vector products combined with iterative methods. We used methods based on the fast Multipole methods and nearest neighbor searching techniques for implementations of the fast matrix-vector products. JA - Aerospace Conference, 2008 IEEE M3 - 10.1109/AERO.2008.4526433 ER - TY - CONF T1 - Fast Multipole Accelerated Boundary Elements for Numerical Computation of the Head Related Transfer Function T2 - IEEE International Conference on Acoustics, Speech and Signal Processing, 2007. ICASSP 2007 Y1 - 2007 A1 - Gumerov, Nail A. A1 - Duraiswami, Ramani A1 - Zotkin,Dmitry N KW - Acceleration KW - Acoustic measurements KW - Acoustic scattering KW - audio signal processing KW - boundary element formulation KW - Boundary element method KW - Boundary element methods KW - boundary-elements methods KW - Costs KW - Ear KW - Fast Multipole Method KW - Frequency KW - Head related transfer function KW - HUMANS KW - Irrigation KW - iterative methods KW - multipole accelerated boundary elements KW - multipole based iterative preconditioned Krylov solution KW - numerical computation KW - Reciprocity KW - Transfer functions AB - The numerical computation of head related transfer functions has been attempted by a number of researchers. However, the cost of the computations has meant that usually only low frequencies can be computed and further the computations take inordinately long times. Because of this, comparisons of the computations with measurements are also difficult. We present a fast multipole based iterative preconditioned Krylov solution of a boundary element formulation of the problem and use a new formulation that enables the reciprocity technique to be accurately employed. This allows the calculation to proceed for higher frequencies and larger discretizations. Preliminary results of the computations and of comparisons with measured HRTFs are presented. JA - IEEE International Conference on Acoustics, Speech and Signal Processing, 2007. ICASSP 2007 PB - IEEE VL - 1 SN - 1-4244-0727-3 M3 - 10.1109/ICASSP.2007.366642 ER - TY - JOUR T1 - Contention-conscious transaction ordering in multiprocessor DSP systems JF - IEEE Transactions on Signal Processing Y1 - 2006 A1 - Khandelia,M. A1 - Bambha,N. K A1 - Bhattacharyya, Shuvra S. KW - contention-conscious transaction ordering KW - Costs KW - data flow graphs KW - Dataflow KW - Delay KW - Digital signal processing KW - digital signal processing chips KW - Embedded system KW - graph-theoretic analysis KW - Instruments KW - Internet telephony KW - interprocessor communication KW - iterative dataflow graphs KW - iterative methods KW - Message passing KW - multiprocessor KW - multiprocessor DSP systems KW - NP-complete problem KW - Processor scheduling KW - scheduling KW - Signal processing KW - synchronization KW - Throughput AB - This paper explores the problem of efficiently ordering interprocessor communication (IPC) operations in statically scheduled multiprocessors for iterative dataflow graphs. In most digital signal processing (DSP) applications, the throughput of the system is significantly affected by communication costs. By explicitly modeling these costs within an effective graph-theoretic analysis framework, we show that ordered transaction schedules can significantly outperform self-timed schedules even when synchronization costs are low. However, we also show that when communication latencies are nonnegligible, finding an optimal transaction order given a static schedule is an NP-complete problem, and that this intractability holds both under iterative and noniterative execution. We develop new heuristics for finding efficient transaction orders, and perform an extensive experimental comparison to gauge the performance of these heuristics. VL - 54 SN - 1053-587X CP - 2 M3 - 10.1109/TSP.2005.861074 ER - TY - JOUR T1 - Robust ego-motion estimation and 3-D model refinement using surface parallax JF - Image Processing, IEEE Transactions on Y1 - 2006 A1 - Agrawal,A. A1 - Chellapa, Rama KW - 3D model refinement KW - algorithms KW - Artificial intelligence KW - Automated;Subtraction Technique; KW - Computer-Assisted;Imaging KW - constant parallax model KW - depth based parallax model KW - digital elevation map KW - epipolar field KW - Image Enhancement KW - Image Interpretation KW - iterative algorithm KW - iterative methods KW - Motion estimation KW - robust ego-motion estimation KW - smooth parallax field KW - surface parallax KW - Three-Dimensional;Information Storage and Retrieval;Pattern Recognition AB - We present an iterative algorithm for robustly estimating the ego-motion and refining and updating a coarse depth map using parametric surface parallax models and brightness derivatives extracted from an image pair. Given a coarse depth map acquired by a range-finder or extracted from a digital elevation map (DEM), ego-motion is estimated by combining a global ego-motion constraint and a local brightness constancy constraint. Using the estimated camera motion and the available depth estimate, motion of the three-dimensional (3-D) points is compensated. We utilize the fact that the resulting surface parallax field is an epipolar field, and knowing its direction from the previous motion estimates, estimate its magnitude and use it to refine the depth map estimate. The parallax magnitude is estimated using a constant parallax model (CPM) which assumes a smooth parallax field and a depth based parallax model (DBPM), which models the parallax magnitude using the given depth map. We obtain confidence measures for determining the accuracy of the estimated depth values which are used to remove regions with potentially incorrect depth estimates for robustly estimating ego-motion in subsequent iterations. Experimental results using both synthetic and real data (both indoor and outdoor sequences) illustrate the effectiveness of the proposed algorithm. VL - 15 SN - 1057-7149 CP - 5 M3 - 10.1109/TIP.2005.864167 ER - TY - JOUR T1 - Computation of scattering from clusters of spheres using the fast multipole method JF - The Journal of the Acoustical Society of America Y1 - 2005 A1 - Gumerov, Nail A. A1 - Duraiswami, Ramani KW - acoustic wave scattering KW - convergence of numerical methods KW - iterative methods KW - matrix multiplication AB - A T-matrix based method of solution of the multiple scattering problem was presented by the authors [J. Acoust Soc. Am. 112, 2688–2701 (2002)]. This method can be applied to the computation of relatively small problems, since the number of operations required grows with the number of spheres N as O(N3), and with the sixth power of the wave number. The use of iterative techniques accelerated using the fast multipole method (FMM) can accelerate this solution, as presented by Koc and Chew [J. Acoust. Soc. Am. 103, 721–734 (1998)] originally. In this study we present a method that combines preconditioned Krylov subspace iterative techniques, FMM accelerated matrix vector products, a novel FMM-based preconditioner, and fast translation techniques that enable us to achieve an overall algorithm in which the cost of the matrix-vector multiplication grows with N as O(N log N) and with the third power of the wave number. We discuss the convergence of the iterative techniques, selection of the truncation number, errors in the solution, and other issues. The results of the solution of test problems obtained with the method for N ∼ 102–104 for different wave numbers are presented. © 2005 Acoustical Society of America. VL - 117 UR - http://link.aip.org/link/?JAS/117/1744/1 CP - 4 M3 - 10.1121/1.1853017 ER - TY - CONF T1 - Modeling image processing systems with homogeneous parameterized dataflow graphs T2 - Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05). IEEE International Conference on Y1 - 2005 A1 - Sen,Mainak A1 - Bhattacharyya, Shuvra S. A1 - Lv,Tiehan A1 - Wolf,W. KW - data consumption KW - data flow graphs KW - data production KW - dynamic dataflow graph KW - graph edges KW - homogeneous parameterized dataflow graphs KW - IMAGE PROCESSING KW - image processing system modeling KW - iteration KW - iterative methods AB - We describe a new dataflow model called homogeneous parameterized dataflow (HPDF). This form of dynamic dataflow graph takes advantage of the fact that in a large number of image processing applications, data production and consumption rates, though dynamic, are equal across graph edges for any particular iteration, which leads to a homogeneous rate of actor execution, even though data production and consumption values are dynamic and vary across graph edges. We discuss existing dataflow models and formulate in detail the HPDF model. We develop examples of applications that are described naturally in terms of HPDF semantics and present experimental results that demonstrate the efficacy of the HPDF approach. JA - Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05). IEEE International Conference on VL - 5 M3 - 10.1109/ICASSP.2005.1416258 ER - TY - JOUR T1 - Complete stagnation of JF - Linear Algebra and its Applications Y1 - 2003 A1 - Zavorin, Ilya A1 - O'Leary, Dianne P. A1 - Elman, Howard KW - Convergence KW - GMRES KW - iterative methods KW - Stagnation AB - We study problems for which the iterative method for solving linear systems of equations makes no progress in its initial iterations. Our tool for analysis is a nonlinear system of equations, the stagnation system, that characterizes this behavior. We focus on complete stagnation, for which there is no progress until the last iteration. We give necessary and sufficient conditions for complete stagnation of systems involving unitary matrices, and show that if a normal matrix completely stagnates then so does an entire family of nonnormal matrices with the same eigenvalues. Finally, we show that there are real matrices for which complete stagnation occurs for certain complex right-hand sides but not for real ones. VL - 367 SN - 0024-3795 UR - http://www.sciencedirect.com/science/article/pii/S0024379502006122 M3 - 16/S0024-3795(02)00612-2 ER - TY - JOUR T1 - Complete stagnation of GMRES JF - Linear Algebra and its Applications Y1 - 2003 A1 - Zavorin, Ilya A1 - O’Leary,Dianne P. A1 - Elman, Howard KW - Convergence KW - GMRES KW - iterative methods KW - Stagnation AB - We study problems for which the iterative method gmres for solving linear systems of equations makes no progress in its initial iterations. Our tool for analysis is a nonlinear system of equations, the stagnation system, that characterizes this behavior. We focus on complete stagnation, for which there is no progress until the last iteration. We give necessary and sufficient conditions for complete stagnation of systems involving unitary matrices, and show that if a normal matrix completely stagnates then so does an entire family of nonnormal matrices with the same eigenvalues. Finally, we show that there are real matrices for which complete stagnation occurs for certain complex right-hand sides but not for real ones. VL - 367 SN - 0024-3795 UR - http://www.sciencedirect.com/science/article/pii/S0024379502006122 M3 - 10.1016/S0024-3795(02)00612-2 ER - TY - JOUR T1 - Low-effort, high-payoff user interface reengineering JF - IEEE Software Y1 - 1997 A1 - Plaisant, Catherine A1 - Rose,A. A1 - Shneiderman, Ben A1 - Vanniamparampil,A. J KW - Business process re-engineering KW - complete system reengineering KW - Design methodology KW - Error analysis KW - Hardware KW - inadequate functionalities KW - interface stability KW - iterative methods KW - low-effort high-payoff user interface reengineering KW - short-term improvements KW - short-term user interface reengineering KW - software engineering KW - Software testing KW - System analysis and design KW - System testing KW - systems re-engineering KW - User centered design KW - user centred design KW - User interfaces AB - Although increasingly sophisticated design methodologies for developing new user interfaces exist, low-effort, high-payoff user interface reengineering represents a new direction-and opportunity. Yet reengineering a working system is complex and risky because of the potential disruption to users and managers, their justifiable fear of change, and the lack of guarantees that such changes will be for the better. Our largely positive experiences with the projects described here lead us to believe that user interface reengineering is a viable and important process. Low effort, high-payoff improvement recommendations can probably be made for most existing systems. Nevertheless, a narrowly focused user interface reengineering plan may be inappropriate when the major problems lie outside the scope of the user interface, such as inadequate functionalities, frequent crashes, and network problems. Attempts at improving less severe problems while ignoring deeper ones may be perceived as insensitive by the users. In such cases it is important to consider either making similar short-term improvements for other parts of the systems or postponing short-term user interface reengineering in favour of a more complete system reengineering. Similarly, the need for interface stability might outweigh the benefits of the short-term improvements if a complete reengineering is planned for the near future. But most likely these proposed diagnostic strategies and opportunities for improvement are only a prelude to the much larger task of business reengineering, which implies extensive user interface reengineering VL - 14 SN - 0740-7459 CP - 4 M3 - 10.1109/52.595958 ER -