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Enhancement of stents using interference of low-frequency ultrasonic echo signals

Journal of Medical Ultrasonics 2004年第2期31卷 67-73页

作者： Ohashi, Gosuke Ohya, Akihisa Tobise, Kazimobu Akiyama, Iwaki Faculty of Engineering Shizuoka University Hamamatsu Japan Institute of Information Sciences and Electronics University of Tsukuba Tsukuba Japan Shoryo Electronic Corporation Kamakura Japan Faculty of Engineering Shonan Institute of Technology Fujisawa Japan Image Processing and Vision Research Laboratory Department of Electrical and Computer Engineering University of California at Santa Barbara Santa Barbara CA 93106-9560 United States

Purpose. We set out to enhance the imaging of stents used for coronary coarctation surgery without imaging the reticulation of the stent. Because the stent is a reticulated structure, there is a relation between ultrasound wavelength and the interstice reticulation that produces the echo. Methods. First we performed computer simulation by ultrasound frequency of transmitted signals to analyze this relation. Then, instead of controlling the transmitted wave, we processed the returned signals through a band-pass filter because of the difficulty of controlling the transmitted waves of diagnostic ultrasound equipment. Following this, we conducted experiments on an agar gel phantom containing a stent to verify the effectiveness of this method. Results. The simulation confirmed that the stent was apparent when the ultrasonic wavelength equaled the product of an integer and twice the interval of the reticulation of the stent. Application of a band-pass filter of 0.8 to 1.5MHz to the waveform returned from the agar gel phantom containing the stent. Conclusions. The effectiveness of this method in depicting the stent was confirmed. © The Japan Society of Ultrasonics in Medicine 2004.

关键词： Interference Received waveform Signal processing Stent Ultrasonic echography

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Dynamic training of hand gesture recognition system

Dynamic training of hand gesture recognition system

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International Conference on Pattern Recognition

作者： A. Licsar T. Sziranyi Department of Image Processing and Neurocomputing University of Veszprém Veszprem Hungary Analogical & Neural Computing Laboratory Computer & Automation Research Institute Hungarian Academy of Sciences (ATOMKI) Budapest Hungary

We developed an augmented reality tool for vision-based hand gesture recognition in a camera-projector system. Our recognition method uses modified Fourier descriptors for the classification of static hand gestures. Hand segmentation is based on a background subtraction method, which is improved to handle background changes. Most of the recognition methods are trained and tested by the same service-person, and training phase occurs only preceding the interaction. However, there are numerous situations when several untrained users would like to use gestures for the interaction. In our new practical approach the correction of faulty detected gestures is done during the recognition itself. Our main result is the quick on-line adaptation to the gestures of a new user to achieve user-independent gesture recognition.

关键词： computer displays Cameras Fault detection Mice Hardware Phase detection System testing Feedback Auditory displays image processing

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Length-limited variable-to-variable length codes for high-performance entropy coding

Length-limited variable-to-variable length codes for high-pe...

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Data Compression Conference (DCC)

作者： J. Senecal M. Duchaineau K.I. Joy Institute for Scientific Computing Research Lawrence Livemore National Laboratory USA Center for Image Processing and Integrated Computing Computer Science Department University of California Davis USA Center for Applied Scientific Computing Lawrence Livemore National Laboratory USA

Arithmetic coding achieves a superior coding rate when encoding a binary source, but its lack of speed makes it an inferior choice when true high-performance encoding is needed. This paper presents the practical implementation of fast entropy coders for binary messages utilizing only bit shifts and table lookups. To limit code table size the proposed code lengths is limited with a type of variable-to-variable (VV) length code created from source string merging. This is referred to as "merged codes". With merged codes it is possible to achieve a desired level of speed by adjusting the number of bits read from the source at each step. The most efficient merged codes yield a coder with a worst-case inefficiency of 0.4%, relative to the Shannon entropy. Using a hybrid Golomb-VV bin coder the compression ratio that is competitive with other state-of-the-art coders, at a superior throughput is achieved.

关键词： Entropy coding image coding Table lookup Throughput Computational modeling Scientific computing Laboratories Degradation Arithmetic image processing

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Evaluation of joint source and channel coding over wireless networks

Evaluation of joint source and channel coding over wireless ...

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International Conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： Yuxin Liu C. Podilchuk E. Delp Video and Image Processing Laboratory (VIPER) School of Electrical and Computer Engineering Pwdue University West Lafayette IN USA Multimedia Research Laboratory Bell Laboratories Lucent Technologies Inc. Murray Hill NJ USA

Transmission of digital video signals over wireless networks demands efficient compression algorithms as well as reliable coding strategies. In this project, we provide a thorough evaluation of the joint source-channel video coding methodology from two points of view: source coding design for error resilience and channel coding for error detection and recovery. We investigate the current ITU video compression standard, H.263+, for 3G wireless transmission. In particular, we concentrate on error resilient features provided within the standard and forward error correction (FEC) to find the optimal combination of various system parameters under different lossy channel conditions.

关键词： Wireless networks Forward error correction Error correction Video compression Resilience Channel coding image coding Laboratories Source coding Error correction codes

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Parallel cell projection rendering of adaptive mesh refinement data

Parallel cell projection rendering of adaptive mesh refineme...

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IEEE Symposium on Parallel and Large-Data Visualization and graphics (PVG)

作者： G.H. Weber M. Ohler O. Kreylos J.M. Shalf E.W. Bethel B. Hamann G. Scheuermann Visualization Group National Energy Research Scientific Computing Center (NERSC) Lawrence Berkeley National Laboratory Berkeley CA USA AG Graphische Datenverabeitung und Computergeometrie FB Informatik University of Kaiserslautern Kaiserslautern Germany Center for Image Processing and Integrated Computing Center for Image Processing and Integrated Computing (CIPIC) Department of Computer Science University of California Davis CA USA Center for Image Processing and Integrated Computing Department of Computer Science University of California Davis CA USA

Adaptive mesh refinement (AMR) is a technique used in numerical simulations to automatically refine (or de-refine) certain regions of the physical domain in a finite difference calculation. AMR data consists of nested hierarchies of data grids. As AMR visualization is still a relatively unexplored topic, our work is motivated by the need to perform efficient visualization of large AMR data sets. We present a software algorithm for parallel direct volume rendering of AMR data using a cell-projection technique on several different parallel platforms. Our algorithm can use one of several different distribution methods, and we present performance results for each of these alternative approaches. By partitioning an AMR data set into blocks of constant resolution and estimating rendering costs of individual blocks using an application specific benchmark, it is possible to achieve even load balancing.

关键词： Adaptive mesh refinement Data visualization Rendering (computer graphics) Spatial resolution Partitioning algorithms Load management Parallel programming graphics Physics computing Computational efficiency

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Supervised training based hand gesture recognition system

Supervised training based hand gesture recognition system

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作者： Licsár, Attila Szirányi, Tamás University of Veszprém Department of Image Processing and Neurocomputing Egyetem u. 10 H-8200 Veszprém Hungary Analogical and Neural Computing Laboratory Computer and Automation Research Institute Hungarian Academy of Sciences Kende u. 13-17 H-1111 Budapest Hungary

We have developed a hand gesture recognition system, based on the shape analysis of static gestures, for Human computer Interaction purposes. Our appearance-based recognition uses modified Fourier descriptors for the classification, of hand shapes. As always found in literature, such recognition systems consist of two phases: training and recognition. In our new practical approach, following the chosen appearance-based model, training and recognition is done in an interactive supervised way: the adaptation for untrained gestures is also solved by hand signals. Our experimental results with three different users are reported. In this paper, besides describing the recognition itself, we demonstrate our interactive training method in a practical application. © 2002 IEEE.

关键词： Gesture recognition

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Supervised training based hand gesture recognition system

Supervised training based hand gesture recognition system

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International Conference on Pattern Recognition

We have developed a hand gesture recognition system, based on the shape analysis of static gestures, for human computer interaction purposes. Our appearance-based recognition uses modified Fourier descriptors for the classification of hand shapes. As always found in literature, such recognition systems consist of two phases: training and recognition. In our new practical approach, following the chosen appearance-based model, training and recognition is done in an interactive supervised way: the adaptation for untrained gestures is also solved by hand signals. Our experimental results with three different users are reported. Besides describing the recognition itself we demonstrate our interactive training method in a practical application.

关键词： Shape Character recognition image processing Laboratories Automation Human computer interaction Application software Control systems Virtual environment Cameras

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A Study of Transfer Function Generation for Time-Varying Volume Data 2

A Study of Transfer Function Generation for Time-Varying Vol...

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2nd IEEE TCVG / Eurographics International Workshop on Volume graphics, VG 2001

作者： Jankun-Kelly, T.J. Ma, Kwan-Liu Visualization And Graphics Research Group Center For Image Processing And Integrated Computing University Of California Department Of Computer Science DavisCA95616 United States

ISBN: (纸本)321183737X

The proper usage and creation of transfer functions for time-varying data sets is an often ignored problem in volume visualization. Although methods and guidelines exist for time-invariant data, little formal study for the timevarying case has been performed. This paper examines this problem, and reports the study that we have conducted to determine how the dynamic behavior of time-varying data may be captured by a single or small set of transfer functions. The criteria which dictate when more than one transfer function is needed were also investigated. Four data sets with different temporal characteristics were used for our study. Results obtained using two different classes of methods are discussed, along with lessons learned. These methods, including a new multiresolution opacity map approach, can be used for semi-automatic generation of transfer functions to explore large-scale time-varying data sets. © VG 2001. All rights reserved.

关键词： Transfer functions

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Linear programming concept visualization

Linear programming concept visualization

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International Conference on Information Visualisation (IV)

作者： J.P. Charalambos E. Izquierdo Image Processing and Computer Graphics Research Laboratory Department of Computer Sciences National University Colombia Department of Electronic Engineering Queen Mary University of London London UK

A visualization scheme as a tool to find the solution of any 3D-linear programming problem is introduced. The presented approach is highly suitable to draw and visualize interactively the feasible region of a given 3D-linear programming problem. It can be used for a better understanding of the solution process when different methods devoted to solve the underlying problem are applied, e.g., the simplex method. The proposed technique comprises sensitive analysis during the solution process and interactive visualization of the feasible region. The analysis leading to the introduced schema also shows that the design of an appropriate and simple vertex representation is crucial to manage any order of degeneracy. To deal with this paradigm and to some extent to formalize it, the concept of adjacency invariance is introduced. Several experiments have been conducted to test and assess the performance of the introduced concepts and techniques.

关键词： Linear programming Visualization Testing computer graphics image processing Appropriate technology Stress Algorithm design and analysis

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Adaptive hierarchical stereo matching using object segmentation and window warping

Adaptive hierarchical stereo matching using object segmentat...

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IEEE International Conference on Systems, Man and Cybernetics

作者： Jae-Chul Kim Byoung-Ho Kang Maeng-Sub Cho Color Imaging Research Team Image Processing Department Computer and Software Technology Laboratory Electronics and Telecommunications Research Institute Taejon South Korea

In this paper, we propose an adaptive stereo matching algorithm to encompass stereo matching problems in projective distortion region. Since the projective distortion region can not be estimated in terms of fixed-size block matching algorithm, we tried to use adaptive window warping method in hierarchical matching process to compensate the perspective distortions. In addition, probability theory was adopted to encompass uncertainty of disparity of points over the window in this study. The proposed stereo matching algorithm has been tested on both disparity map and 3D model view. The experimental results show that remarkable improvement is obtained in the projective distortion region.

关键词： Object segmentation Optical distortion Uncertainty Cameras Solid modeling Color image processing Laboratories Software algorithms Testing

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