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An efficient wavelet-based deblocking algorithm for highly compressed images

IEEE TRANSACTIONS ON CIRCUITS AND systems FOR VIDEO TECHNOLOGY 2001年第11期11卷 1193-1198页

作者： Wu, SH Yan, H Tan, Z City Univ Hong Kong Dept Elect Engn Kowloon Hong Kong Peoples R China Xi An Jiao Tong Univ Sch Elect & Informat Engn Xian 710049 Peoples R China Univ Sydney Sch Elect & Informat Engn Sydney NSW 2006 Australia

In this paper, a new post-processing method is proposed in the wavelet domain for the suppression of blocking artifacts in compressed images. The novelty of our method is that we can obtain soft-threshold values based on the difference between the wavelet transform coefficients of image blocks and the coefficients of the entire image to threshold high-frequency wavelet coefficients in different subbands using different values and strategies. The threshold value is made adaptive to different images and characteristics of blocking artifacts. In particular, the new method is robust, fast, and works remarkably well for different discrete-cosine-transform-based compressed images at low bit rates. The method is nonlinear, computationally efficient, and spatially adaptive. Another advantage of the new method is that it retains sharp features in the images since it only removes artifacts. Experimental results show that the proposed method can achieve a significantly improved visual quality and also increase the PSNR in the output image. Our method also performs better than algorithms based on overcomplete wavelet presentation for images containing a large portion of texture.

关键词： blocking artifacts discrete cosine transform (DCT) image compression soft thresholding wavelet transforms

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Three-dimensional pattern recognition: algorithms and systems

Three-dimensional pattern recognition: algorithms and system...

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11th Conference on Automatic Target Recognition

作者： Javidi, B Tajahuerce, E Univ Connecticut Dept Elect & Syst Engn Storrs CT 06269 USA

ISBN: (纸本)0819440744

We present a technique to perform nonlinear three-dimensional (3D) pattern recognition, and we analyse the performance of the Fourier plane nonlinear filters in terms of signal-to-noise ratio (SNR). Using in-line digital holography, the complex amplitude distribution generated by a 3D object at an arbitrary plane located in the Fresnel diffraction region is recorded by phase-shifting interferometry. Information about the 3D object shape, location and orientation is contained in the digital hologram. This allows us to perform 3D pattern-recognition techniques using non-linear correlation filters. Then we obtain a range nonlinearities for which the SNR is robust to the variations in input noise bandwidth, which keeps the output SNR of the filter stable relative to changes in the noise bandwidth, using Karhunen-Loeve series expansion of the noise process. This is shown both by analytical estimates of the SNR for nonlinear filters as well as by experimental simulations.

关键词： three-dimensional image processing three-dimensional patter recognition three-dimensional imaging nonlinear processing digital holography

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Particle motion tracking utilizing a high-resolution digital CCD camera

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GEOTECHNICAL TESTING JOURNAL 2000年第1期23卷 123-134页

作者： Paikowsky, SG xi, F Univ Massachusetts Dept Civil & Environm Engn Geotech Engn Res Lab Lowell MA 01854 USA

Digital imaging acquisition and processing is applied for the tracking of a two-dimensional assembly of disks. The disks are used to assemble models for studying granular material behavior for which the kinematics of the individual particles, and hence the disks' trajectory during motion, are of cardinal importance. Large particle size is dictated by photoelastic interparticle interaction analysis. Therefore, a sufficiently large representative number of particles results in a large physical model. The system requirements of a sizable physical model comprised of a large number of particles, and simultaneous precise tracking of all particles, are achieved through the use of high-resolution digital CCD camera and semi-automatic image processing and analysis algorithms. The physical system setup, image acquisition procedure, calibration, accuracy, and algorithms of analysis are described. The system's performance is demonstrated through test results describing the displacement field along with the motion and interaction of individual particles. The system's advantages in providing detailed tracking of a large number of particles with minimal labor are unmatched by any other technique. The data obtained by such systems allow a better understanding of particulate media behavior with the ability to examine and calibrate numerical models on an individual grain basis.

关键词： image processing granular material particle interface shear tracking CCD

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A tracking gate algorithm based on optimal performance of data association

A tracking gate algorithm based on optimal performance of da...

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International Conference on Signal processing Proceedings (ICSP)

作者： Minghui Wang Zhisheng You Rongchun Zhao Jiansun Nie The Department of the Computer Science and Engineering Northwest Polytechnical University Xi'an China The Inst. of the Image & Graphics Sichuan University Chengdu China

Gating is a very important technique of data association. Creating an excellent gate algorithm, which could efficiently decrease the number of extraneous returns falling within the gate, can improve the data association accuracy and decrease the computation complexity. Hence, a novel tracking gate algorithm is presented. The main feature of our method is to estimate the size of gate by calculating the optimal solution of an appraising function of the performance of the data association algorithm. A comparison of our method to classical methods demonstrates that our algorithm is superior to these methods, especially in a heavy clutter and false alarm environment.

关键词： Appraisal State estimation Target tracking Computer science Computer graphics Partitioning algorithms Surveillance Sensor systems Nearest neighbor searches Personal digital assistants

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Frequency-domain properties of the innovations sequence and their applications 1

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IFAC Proceedings Volumes 1999年第2期32卷 4165-4170页

作者： Jiang Gao Baosheng Hu Guanzhong Dai Image Processing Division Dept. of Electronic Engineering Tsinghua University Beijing 100084 PRC Institute of Systems Engineering Xi'an Jiaotong Univ. Xi'an 710049 PRC Dept. of Automatic Control Northwestern Polytechnic Univ. Xi'an 710072 PRC

Some frequency-domain properties of innovations sequence are studied. As their applications, a frequency-domain method for the identification of statistical parameters in adaptive Kalman filtering is proposed. This method has clear physical meaning, and by using the weighted least-squares estimation algorithm, the statistical parameters can be identified accurately and robustly. A sufficient condition for the identifiability of model mismatches with arbitrary phase characters in adaptive Kalman filtering is also given, by using the structure of innovations sequence and the theory of higher-order statistics.

关键词： Kalman filters innovation spectrum estimation higher-order statistics adaptive algorithms

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Performances of remote digital processing in automated non-destructive evaluation

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SENSORS AND ACTUATORS A-PHYSICAL 1998年第1-3期68卷 447-453页

作者： Ullate, LG Ibanez, A Anaya, JJ Sanchez, MT CSIC Inst Automat Ind E-28500 Madrid Spain

Recent advances in transducers, electronic techniques, computer architectures and digital signal processing provide substantial improvements in automated non-destructive evaluation (ANDE) techniques. ANDE must fulfil very strict specifications, especially related to reliability (i.e., the quality of images, repetitiveness of acquisitions, etc.) and to the inspection speed. Multi-channel operation and digital signal processing provide a good solution to overcome strict NDE demands. In this paper, an approach based on a multi-channel remote system (R-SENDAS(1)) is presented, in which both signal conditioning and digital processing are done *** remote system performs complex algorithms for noise suppression, resolution improvement and smart data reduction at a sustained global processing rate of 10M samples per second. The central computer operates in parallel to attend to other jobs such as movement control, image display, etc. Several features of this solution related to noise immunity, system flexibility, system parallelism and other advantages are analysed in the paper. (C) 1998 Elsevier Science S.A. All rights reserved.

关键词： multiple-sensor systems non-destructive evaluation digital signal processing and parallel architectures

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VLSI Array Architectures for Pyramid Vector Quantization

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Journal of VLSI Signal processing systems for Signal, image, and Video Technology 1998年第2期18卷 141-154页

作者： Jung, Bongjin Burleson, Wayne P. Digital Semiconductor Co. Hudson MA 01749 77 Reed Road HLO2-3/D11 United States Dept. of Elec. and Comp. Engineering University of Massachusetts Amherst MA 01003 United States Rensselaer Polytechnic Institute United States University of Massachusetts Amherst MA United States Digital Semiconductor Co. Hudson MA United States Dept. of Elec. and Comp. Engineering University of Massachusetts Amherst MA United States MIT United States University of Colorado United States VLSI Technol. Inc. Fairchild S. United States IEEE ACM Sigma Xi United States

We present parallel algorithms and array architectures for pyramid vector quantization (PVQ) [1] for use in image coding in low-power wireless systems. PVQ presents an alternative to other quantization methods which is especially suitable for symmetric peer-to-peer communications like video-conferencing. But, both the encoding and decoding algorithms have data-dependent iteration bounds and data-dependent dependencies which prevent efficient parallelization of the algorithms for either hardware or software implementations. We perform an algorithmic transformation [2] to convert the data-dependent regular algorithms to equivalent data-independent algorithms. The resulting regular algorithms exhibit modular and regular structures with minimal control overhead;hence, they are well suited for VLSI array implementation in ASIC or FPGA technologies. Based on our parallel algorithms and systematic design methodologies [3], we develop linear array architectures. Both encoder and decoder architectures consist of L identical processors with local interconnections and provide O (L) speed-up over a sequential implementation, where L is the dimension of a vector. The architectures achieve 100 % processor utilization and permit power savings through early completion. A combined encoder-decoder architecture is also presented.

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Implementation of an edge detection algorithm in a reconfigurable computing system

Implementation of an edge detection algorithm in a reconfigu...

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Brazilian Symposium on Integrated Circuits and systems Design

作者： R.C.D.M. Tavares C.J.N. Coelho A.D.A. Araujo A.O. Fernandes Dept. of Comput. Sci. Univ. Fed. de Minas Gerais Belo Horizonte Brazil Computer Engineering Laboratory-Computer Science Department Universidade Federal de Minas Gerais Brazil Universidade Federal de Minas Gerais Belo Horizonte MG BR

This paper presents the implementation of a coprocessor that speeds up Roberts gradient edge detection on monochromatic images with 256 gray levels. The coprocessor is implemented in a reconfigurable computing system ... 详细信息

关键词： image edge detection Hardware Costs Coprocessors Software performance Field programmable gate arrays Microprocessors Computer architecture Silicon Signal processing algorithms

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Macro and micro freeway Automatic Incident Detection (AID) methods based on image processing

Macro and micro freeway Automatic Incident Detection (AID) m...

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Proceedings of the 1997 IEEE Conference on Intelligent Transportation systems, ITSC

作者： Zifeng, Jiang Xi'an Highway Univ Shaanxi Province China

This paper first gives brief introduction to freeway Automatic Incident Detection (AID) algorithms on loop detector and it's existing problems, then proposes potential micro and macro freeway AID methods based on image processing and tries to find how difficult the problems are, and finally, from image processing viewpoint presents some possible solutions.

关键词： Intelligent vehicle highway systems

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Efficient Implementation Methodology of Fast FIR Filtering algorithms on DSP

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Journal of VLSI Signal processing systems for Signal, image, and Video Technology 1997年第1期16卷 81-103页

作者： Zergaïnoh, Anissa Duhamel, Pierre Vidal, Jean Pierre Institut Galilée 93430 Villetaneuse Avenue Jean Baptiste Clément France ENST/SIG 75013 Paris 46 rue Barrault France INT/SIM 91011 Evry 9 rue Charles Fourier France University of Orsay Paris XI France INT France Natl. Institute for Applied Sciences Rennes France Orsay University Orsay France Thomson-CSF Paris France Natl. Res. Ctr. in Telecom. Issy les Moulineaux France Télécom Paris (ENST) France Signal Processing Department IEEE Transactions on Sign. Proc. IEEE Signal Processing Letters INT Evry Teach. Digit. Sign. Proc. France CNAM Paris France

A class of Finite Impulse Response (FIR) filtering algorithms based either on short Fast Fourier Transforms (FFT) or on short length FIR filtering algorithms was recently proposed. Besides the significant reduction of the arithmetic complexity, these algorithms present some characteristics which make them useful in many applications, namely a small delay processing (independent on the FIR filter length) as well as a multiply-add based computational structure. These algorithms are presented in a unified framework, thus allowing an easy combination of any of them. However, a remaining difficulty concerns the implementation of the fast algorithms on Digital Signal Processors (DSP), given the DSP finite resources (number of pointers, registers and memory), while keeping as much as possible the improvement brought by the reduction of the arithmetic complexity. This paper provides an efficient implementation methodology, by organizing the algorithm in such a way that the memory data access is optimized on a DSP. As a result, our implementation requires a constant number of pointers whatever the algorithm combination. This knowledge is used in a DSP code generator which is able to select the appropriate algorithm meeting the application constraints, as well as to generate automatically an optimized assembly code, using macro-instructions available in a DSP-dependent library. An improvement of more than 50% in terms of throughput (number of machine cycles per point) compared to the implementation of the direct convolution is generally achieved.

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