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IEEE International Conference on image processing

作者： P. Salama N. Shroff E.J. Delp Visual Communications Laboratory Department of Electrical and Computer Engin Indiana University-Purdue University Indianapolis Indianapolis IN USA Video and Image Proc. Laboratory VIPER School of Electrical and Computer Engin Purdue University West Lafayette IN USA

In ATM networks cell loss or channel errors can cause data to be dropped in the channel. When digital images/video are transmitted over these networks one must be able to reconstruct the missing data so that the impact of the errors is minimized. We overview the problem of using EZW encoders in channels where data-loss is possible. We also describe an error resilience scheme based on unequal error protection and data interleaving that addresses the problem of using rate scalable encoders over ATM networks.

关键词： Resilience Codecs Asynchronous transfer mode Wavelet coefficients Decoding Intelligent networks Digital images image reconstruction Computer errors Video compression

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Adaptive vector LUM smoother

Adaptive vector LUM smoother

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IEEE International Conference on image processing

作者： R. Lukac S. Marchevsky Department of Electronics and Multimedial Communications Technical University of Košice Kosice Slovakia

A new vector approach, the adaptive vector LUM smoother for color images is presented. The novelty of the proposed method lies in the two-stages adaptive choice of the estimate, where in the first filter stage (N+1)/2 outputs with all smoothing levels done by the vector LUM smoother with window size N are generated. In the next filter stage, one of (N+1)/2 possible samples is adaptively selected to determine the filter output depending on the local information, by the filter window. Thus, the proposed method provides an optimal estimate in the sense of objective criteria. In addition, the filter output is constrained to be a sample from an input set that cannot result in color artifacts.

关键词： Adaptive filters Colored noise Smoothing methods Information filtering Information filters Statistics Color Satellites Humans visual system

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Temporal analysis of cache prefetching strategies for multimedia applications

Temporal analysis of cache prefetching strategies for multim...

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IEEE International Conference on Performance, Computing and communications (IPCCC)

作者： R. Cucchiara M. Piccardi A. Prati DSI University of Modena and Reggio Emilia and INFM Modena Italy DI University of Ferrara Ferrara Italy

ISBN: (纸本)0780370015

Prefetching is a widely adopted technique for improving performance of cache memories. Performances are typically affected by the design parameters, such as cache size and associativity, but also by the type of locality embodied in the programs. In particular multimedia tools and programs handling images and video are characterized by a bi-dimensional spatial locality that could be greatly exploited by the inclusion of prefetching in the cache architecture. In this paper we compare some prefetching techniques for multimedia programs (such as MPEG compression, image processing, visual object segmentation) by performing a detailed evaluation of the memory access time. The goal is to prove that a significant speedup can be achieved by using either standard prefetching techniques (such as OBL or adaptive prefetching) or some innovative and image-oriented prefetching methods like the neighbor prefetching described in the paper. Performance are measured with the PRIMA trace-driven simulator.

关键词： Prefetching Streaming media image coding image processing Cache memory Transform coding Filtering algorithms Pixel History Performance analysis

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Nonlinear smoothing filter using adaptive radial clustering

Nonlinear smoothing filter using adaptive radial clustering

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

作者： I.Y.-H. Gu Vasile Gui Department of Signals and Systems Chalmers University of Technology Sweden Department of Electronics and Communications Polytechnic University of Timisoara Romania

A novel adaptive nonlinear filter is proposed aimed at smoothing homogenous regions while maintaining image structures. The filter can be utilized as a pre-processing tool in image segmentation and edge estimation for improving the results. Several special features are introduced to the filter, including using local adaptive radial clustering and pixel filtering to exclude the influence of outliers and to maintain image structures; using the steepest-ascent method to iteratively update pixels to the nearest clusters obtained by mean-shift; and introducing highly parallel processing by using random seed samples and their associated data blocks which enables fast processing and the global optimum solution of the nonlinear filter. Experiments were done on images of various complexities, and good results were obtained. Evaluations of the filter were also done in terms of edge preservation and image segmentation.

关键词： Smoothing methods Adaptive filters Nonlinear filters Filtering image segmentation Pixel Parallel processing visual perception Computer vision Maximum likelihood detection

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Moving target tracking algorithm based on the confidence measure of motion vectors

Moving target tracking algorithm based on the confidence mea...

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IEEE International Conference on image processing

作者： Jin-Sung Lee Kwang-Yeon Rhee Seong-Dae Kim Visual Communications Laboratory Department of EECS Korea Advanced Institute of Science and Technology Taejon South Korea

Change detection using a difference picture has been used to detect the location of moving targets and to track them. This method needs the assumption of a static camera, and global motion compensation is required in the case of a moving camera. We suggest a method for finding minimum bounding rectangles (MBRs) of moving targets in the image sequences using moving region detection, especially with a moving camera. If the global motion parameter is inaccurately estimated, the estimated locations of targets will not be accurate either. To alleviate this problem, we introduce the concept of the confidence measure and achieve more accurate estimation of global motion. With a moving camera, the new global motion estimation algorithm performs more precisely and it reduces the background compensation errors for change detection. Experimental results show that the proposed method successfully removes the background region and extracts MBRs of the targets.

关键词： Target tracking Motion measurement Motion estimation Cameras Change detection algorithms Motion detection Object detection Motion compensation image sequences Real time systems

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Frame reconstruction of the Laplacian pyramid

Frame reconstruction of the Laplacian pyramid

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

作者： M.N. Do M. Vetterli Laboratory for Audio-visual Communications Swiss Federal Institute of Technology Lausanne Switzerland Department of EECS University of California Berkeley Berkeley CA USA

We study the Laplacian pyramid (LP) as a frame operator, and this reveals that the usual reconstruction is suboptimal. With orthogonal filters, the LP is shown to be a tight frame, thus the optimal linear reconstruction using the dual frame operator has a simple structure as symmetrical with the forward transform. For more general cases, we propose an efficient filter bank for reconstruction in the LP that is shown to perform better than the usual method. Numerical results indicate that gains of more than 1 dB are actually achieved.

关键词： Laplace equations image reconstruction Filter bank image coding Reconstruction algorithms Frequency Nonlinear filters Filtering Wavelet transforms Multidimensional systems

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On the compression of two-dimensional piecewise smooth functions

On the compression of two-dimensional piecewise smooth funct...

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IEEE International Conference on image processing

作者： M.N. Do P.L. Dragotti R. Shukla M. Vetterli Audio-Visual Communications Laboratory Swiss Federal Institute of Technology Lausanne Switzerland Department of EECS University of California Berkeley Berkeley CA USA

It is well known that wavelets provide good non-linear approximation of one-dimensional (1-D) piecewise smooth functions. However, it has been shown that the use of a basis with good approximation properties does not necessarily lead to a good compression algorithm. The situation in 2-D is much more complicated since wavelets are not good for modeling piecewise smooth signals (where discontinuities are along smooth curves). The purpose of this work is to analyze the performance of compression algorithms for 2-D piecewise smooth functions directly in a rate distortion context. We consider some simple image models and compute rate distortion bounds achievable using oracle based methods. We then present a practical compression algorithm based on optimal quadtree decomposition that, in some cases, achieve the oracle performance.

关键词： Polynomials image coding Signal processing algorithms Rate-distortion Laboratories Performance analysis Compression algorithms Approximation methods Fourier series Nonlinear distortion

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Trajectories adaptive prediction based on image processing cerebellar model for ocular-motor systems in robotic heads

Trajectories adaptive prediction based on image processing c...

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IEEE International Conference on Systems, Man and Cybernetics

作者： J.L. Pedreno-Molina A. Guerrero-Gonzalez F. Garcia-Cordova J. Lopez-Coronado Dept. of Information Technologies and Communications Politechnical University of Cartagena Cartagena SPAIN

In this work, a neural controller for delay compensation in image samples detected by an active vision system of robotic heads, in ocular tracking tasks is presented. This control architecture based on CMAC (cerebellar model articulation controller) model has the capacity of learning favored trajectories with less prediction error. This property is very important in robotic tasks of controlling the grasping or assembling of objects by a robotic arm. The main advantage of this cerebellar model is that the output is evaluated by means of a small number of memory cells that implies a high answer speed. Indeed, this visual robotic control avoids (as does the human system) the need to know the kinematics of the process. This prediction module has been integrated in an architecture of visual-motor coordination based on VAM (vector associative maps) models.

关键词： Trajectory image processing Robot kinematics Predictive models Robotic assembly Control systems Robot control Delay Machine vision Robot vision systems

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Adaptive processing with quadratic programming and LPF for reducing blocking artifacts in DCT image coding

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Electronics and communications in Japan, Part I: communications (English translation of Denshi Tsushin Gakkai Ronbunshi) 2001年第4期84卷 50-59页

作者： Fukuda, Koichi Kawanaka, Akira Faculty of Science and Technology Sophia University Tokyo 102-8554 Japan

In many image coding methods, the discrete cosine transform (DCT) is used. When the compression ratio is increased, blocking artifacts are generated in the reconstructed image due to quantization error. To resolve this problem, a method is proposed to adaptively change the suppression process of distortion depending on the block. In this method, each block is classified into (1) the flat part where the pel values change monotonically by the value of the received DCT coefficient and (2) the dynamic part. In the block in the flat part, the DCT coefficients are estimated within the quantization width by the quadratic programming method, and the block is regenerated by replacing the received coefficients. The continuity at the block boundary and the boundary pel values after smoothing are used as the objective function. Higher-order DCT coefficients can be estimated successively. In the region where the variation of the pel values is substantial, human visual sensitivity is not sufficient for the distortion. Therefore, the block boundary is smoothed with a low-pass filter (LPF) in the block in the variable part. This method is used for processing of several images. It is demonstrated that the SNR is better than those in the JPEG reconstruction method, ac coefficient prediction method, and the LPF method. Overall, a high-quality reconstructed image is obtained with the blocking artifacts are suppressed.

关键词： image coding

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Application of stereovision in a navigation aid for blind people

Application of stereovision in a navigation aid for blind pe...

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International Conference on Information, communications and Signal processing

作者： F. Wong R. Nagarajan S. Yaacob Artificial Intelligence Research Group Universiti Malaysia Sabah Kota Kinabalu Sabah Malaysia

A "Navigation Aid for visually Impaired" (NAVI) system has been developed in UMS in 2001 and improved in 2002. The NAVI system comprises of 3-part functioning units namely a digital video camera, a single board computer and a headphone. The single camera limitation in providing the depth information, which is critical for navigation purposes, has prompted the extension into a stereovision system by using two cameras. This stereovision system also uses the fuzzy-based segmentation procedure as an image preprocessing package that was developed for the single camera NAVI but with an additional adaptive loop. The segmented images undergo a rule-based stereo matching procedure. From the matching features, the disparity is computed. The disparity in combination with information of focal length as well as the space between two cameras provides the information on the distance between cameras and object. This distance information is incorporated into the final processed image as four gray levels such as white, light gray, dark gray and black. The size and location of object in the visual plane is then conveyed to the blind individual by means of a structured coded sound. The distance information is represented by means of verbal sound. Preliminary experimental analysis reveals a promising new approach for developing a navigational aid for blinds through the transformation of stereo image to stereo sound.

关键词： Navigation image segmentation Headphones Shape Digital cameras Portable computers Artificial intelligence Information technology Packaging image analysis

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