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Digital Signal Processing Workshop Proceedings, 1996., IEEE

Date 1-4 Sept. 1996

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  • 1996 IEEE Digital Signal Processing Workshop Proceedings

    Publication Year: 1996
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    Freely Available from IEEE
  • Author index

    Publication Year: 1996 , Page(s): 519 - 521
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    Freely Available from IEEE
  • Optimum feedback quantizers for Laplacian pyramids

    Publication Year: 1996 , Page(s): 1 - 4
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    This paper addresses the problem of distortion allocation in a multi-layer image encoder based on an enhanced Laplacian pyramid with quantization noise feedback. An entropy-minimizing optimum quantization strategy is obtained by defining an equivalent memoryless pyramid entropy that, for the case of quantization feedback, is a function of rates and distortions at each pyramid level. By also modelling the propagation of quantization errors throughout the pyramid, a compact closed-form formulation is derived for the equivalent entropy. Such a model yields the optimum amounts of distortion at the various resolution layers, regardless of the first-order distributions of the data. Results are reported in terms of entropy for a Laplacian PDF varying with the quantization step sizes and the adjustable parameters of the pyramid-generating filters View full abstract»

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  • Quality of synthesis and analysis methods for fractional Brownian motion

    Publication Year: 1996 , Page(s): 307 - 310
    Cited by:  Papers (2)
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    The article compares the quality of synthesis and analysis methods for fractional Brownian motion (fBm). Three conditions are necessary and sufficient for a process to be fBm. This allows one to check the correspondence between a given synthesis method and the fBm model. Two synthesis methods among 6 tested give good results. Reference signals obtained by these 2 methods are used to evaluate 8 analysis methods. Three estimators have a low bias and a variance close to the Cramer-Rao lower bound View full abstract»

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  • Combined two nonlinear image processings for speckle-free imaging with the optical array imaging system

    Publication Year: 1996 , Page(s): 29 - 32
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    In previous articles an optical array imaging system has been presented, where after collecting the array data the eigenvector with the largest eigenvalue is derived and it is computationally beamsteared to get images of the object. Images obtainable with this system have serious speckle noise. Two nonlinear processing methods are applied to reduce the speckle noise. One method is to average the intensity images over the parameter of the array elements used for laser light transmission. The other is to apply a Gaussian low-pass filter to the averaged image after taking its logarithm. Their usefulness was examined by computer simulation and it was shown that almost speckle-free imaging is achievable with little effects on image resolution View full abstract»

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  • Teaching wavelets with Java on the information superhighway

    Publication Year: 1996 , Page(s): 101 - 104
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    One of the most exciting new developments on the information superhighway is the Java language of the Sun Microsystem. Java is portable, powerful, and network-aware. This paper presents some ideas and experiments on teaching wavelets and signal processing using Java View full abstract»

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  • Digital signal processing by employment of generalized algorithm

    Publication Year: 1996 , Page(s): 478 - 481
    Cited by:  Papers (3)
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    Questions of detector synthesis on basis of the generalized signal processing algorithm are considered. Sensitivity to changing of the internal noise variance relative to the calculated variance and probability of error for analog-to-digital conversion of a random input process are investigated for generalized and optimal detectors View full abstract»

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  • Application of cone detectors to detection of signals in structured interference

    Publication Year: 1996 , Page(s): 466 - 469
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    The paper addresses a specific case of the detection of signals in noisy environments. In the situation to be considered, noise is modeled as additive Gaussian noise. Signals, and interference of known structure, are modeled as belonging to linear subspaces. The paper reviews and extends previous work on this problem by applying cone classes to model additional information of the relative energy of signals to structured interferences. Detectors designed with this extended model are compared to classical subspace detectors. An example is given to illustrate possible improvements using this new detection scheme. Such an example is also applicable to the multisensor array problem in which windowing and sequencing signal areas of the array record can produce periodic sequences View full abstract»

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  • A noise cancellation algorithm based on hypergraph modeling

    Publication Year: 1996 , Page(s): 5 - 8
    Cited by:  Papers (1)
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    Although the binary relations used in proximity graphs are relevant for many basic situations, they cannot represent the structuration process of digital images. In this paper we show that hypergraph theory is a more appropriate frame to describe the neighborhood relations that can be formalized between pixels. We illustrate the effectiveness of such a model by deriving a noise cancellation algorithm based on a basic combinatoric property of hypergraphs View full abstract»

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  • A new approach to piecewise linear modeling of time series

    Publication Year: 1996 , Page(s): 502 - 505
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    Due to the inherent non-linearity and non-stationarity of a wide class of time series, nonlinear models have been the object of an increasing interest over the past years. Piecewise linear models, in which a linear sub-model is associated with each region of a state-space decomposition, have been proposed as an attractive alternative to threshold autoregressive models. However, it is still unclear how this type of models can be actually estimated. We show how a new combinatorial optimization approach, which we devised for the general problem of piecewise linear model estimation, can be successfully applied to piecewise linear modeling of time series. The idea is to focus on the inconsistent linear system that arises when considering a simple linear model and to partition it into a minimum number of consistent subsystems (MIN PCS). Although the resulting problem (MIN PCS) is NP-hard, satisfactory approximate solutions can be obtained using simple variants of the perceptron algorithm studied in the artificial neural network literature. Simulation results for two well-known chaotic time series are reported View full abstract»

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  • Image compression using pyramidal distance order statistic filtering

    Publication Year: 1996 , Page(s): 33 - 36
    Cited by:  Papers (1)
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    Pyramidal data structure has proven useful in efficient progressive image transmission coding algorithms. A novel image coding algorithm is presented. This algorithm uses distance order statistic filters to form the pyramidal structure. It is applied to real images and found to perform efficiently in terms of image quality at a low bit rate. In noisy conditions the algorithm is adapted to remove noise by using DOS filtering View full abstract»

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  • Frame analysis of wavelet type filter banks

    Publication Year: 1996 , Page(s): 435 - 438
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    The discrete wavelet transform, and multiresolution analysis, can be viewed as the application of a non-uniform filter bank. The polyphase matrix representation of the corresponding frame operator is given for general oversampled wavelet-type filter banks. The issue of lower and upper bounds of the frame and their relation to those of the underlying one level filter bank frame is treated, and bounds are given in a few special cases. A few examples are presented demonstrating the use of the results obtained View full abstract»

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  • New results on the evaluation of equalizers performance

    Publication Year: 1996 , Page(s): 462 - 465
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    An important feature in the analysis of a digital linear transmission system is the evaluation of its intersymbol interference phenomenon. A suitable measure of performance is represented by the probability of error. We present a new upper bound on the probability of error in PAM systems. The main feature of this bound is that it depends on the variance and fourth-order cumulant of the measurable equalizer output and on the a-priori known statistics of the channel input. It can therefore be useful for an a-posteriori evaluation of the equalization accuracy in a blind equalization context View full abstract»

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  • Efficient adaptive filtering in subbands using IIR filter banks

    Publication Year: 1996 , Page(s): 61 - 64
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    This paper deals with a structure for implementing adaptive filters using orthogonal, lossless filter banks. Previously, only FIR filter banks have been used for this structure. We demonstrate that also computationally efficient IIR filter banks can be used even if the adaptive filter to be implemented is an FIR filter. We show that the computational advantages obtained using IIR filters do not lead to performance degradations. It is also demonstrated that the convergence properties of the subband adaptive system-in contrast to the least mean square (LMS) algorithm and transform domain adaptive algorithms based on for example the discrete cosine transform (DCT), is robust with respect to the properties of the input signal to the adaptive filter View full abstract»

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  • Sub-band, dual-channel adaptive noise cancellation using normalised LMS

    Publication Year: 1996 , Page(s): 327 - 330
    Cited by:  Papers (2)
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    An adaptive noise cancellation scheme for speech processing is described. Adaptive filters are implemented in sub-bands, based on a model of the human cochlea. A modification to the LMS structure is introduced which guarantees stability and convergence. This modification, a non-recursive normalisation, is used both in a wideband and in a sub-band implementation of the scheme. The effect of this normalisation is to cause the speech to be distorted, indicating that there is little benefit in using normalised LMS in a sub-band scheme, whether the application uses classical or intermittent noise cancellation View full abstract»

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  • Generation of chaotic signals with n-dimensional uniform probability distribution by digital filter structures

    Publication Year: 1996 , Page(s): 486 - 489
    Cited by:  Papers (1)
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    This paper deals with the generation of chaotic signals which have a uniform probability distribution up to nth-order. First a generator structure containing a static nonlinearity and a dynamical subsystem is deduced and the system characteristics are specified. Then conditions for the generation of continuous-value signals with nth-order uniform distribution are derived. For the special case of digital filter structures with chaotic behaviour the condition is simply that one specified parameter has to be an integer. Finally problems of continuous-value and discrete-value analysis and realisation are discussed. Some simulation results are provided View full abstract»

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  • Recognition of facial expressions using associative memory

    Publication Year: 1996 , Page(s): 243 - 246
    Cited by:  Papers (2)
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    We extract the movements of 8×10 regions of the face by using optical flow and simplify the information by considering whether a particular region of the face moved or not. By applying this information in a Hopfield neural network based on a discrete model, we try to absorb the differences between individuals and the degree of feelings effectively. We carried out an experiment with 144 examples of image data. The results of before and after applying the data in the Hopfield neural network were 61.8% and 71.5% respectively View full abstract»

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  • Shape characterization by using the Gabor transform

    Publication Year: 1996 , Page(s): 215 - 218
    Cited by:  Papers (1)
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    This paper introduces a novel framework for 2D shape analysis from its outline by using the Gabor transform (GT). The shape's boundary is represented by a complex signal, which is analyzed by the GT. Three automatic methods for analyzing the GT representation are discussed. Experimental results have shown that the GT can be used in the identification of dominant points as well as contour regions presenting periodic patterns (both deterministic and statistic patterns). Some results for synthetic and real images are presented and discussed View full abstract»

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  • A simple method of broad band speech recovery from narrow band speech for quality enhancement

    Publication Year: 1996 , Page(s): 173 - 175
    Cited by:  Papers (1)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    This paper describes a system that can enhance the quality of speech signals that have been severely band limited during transmission. We have already proposed a spectrum widening method that utilizes aliasing in sampling rate conversion with digital filtering for spectrum shaping. This paper proposes a new method that offers improved performance in terms of spectrum distortion characteristics. Implementation procedures are clarified, and its performance is discussed. The proposed method can effectively enhance speech quality View full abstract»

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  • An MPEG-2 video decoder DSP architecture

    Publication Year: 1996 , Page(s): 199 - 202
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    The MPEG-2 video standard is a generic international standard for applications such as digital storage media, television broadcasting, and multimedia. A novel MPEG-2 video decoder architecture is presented. The use of dedicated processing elements in an asynchronous communication structure gives a high degree of modularity. A semi-static scheduling scheme is used to keep the resource utilization high View full abstract»

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  • Step-like weighting windows for DSP in spectral analysis and antenna arrays

    Publication Year: 1996 , Page(s): 362 - 365
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    Step-like weighting windows are proposed for various applications in digital signal processing. Their parameters are optimized to minimize either the maximal sidelobe level of the corresponding frequency response (equidistant array pattern) or the ratio of the energies concentrated in the sidelobes and in the mainlobe. These parameters together with the mainlobe width are compared to the corresponding values of the optimal Dolph-Chebyshev and Kaiser-Bessel responses. Several advantages provided by the step-like window implementation are considered View full abstract»

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  • On the use of a modified fast affine projection algorithm in subbands for acoustic echo cancelation

    Publication Year: 1996 , Page(s): 354 - 357
    Cited by:  Papers (7)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    The fast affine projection (FAP) has been proposed recently as a new adaptive filtering algorithm which possesses LMS like complexity but may achieve RLS like convergence. We investigate the use of FAP algorithms in subbands for acoustic echo cancellation (AEC). To this end, some modifications are first made on the FAP based on the consideration of the numerical stability. The modified FAP algorithm is then used in a complex adaptive subband filter structure for AEC. Advantages of the resulting subband FAP over the full-band NLMS scheme in terms of both complexity and performance are demonstrated by simulations View full abstract»

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  • Adaptive pre-equalization using neural-like algorithm

    Publication Year: 1996 , Page(s): 439 - 441
    Cited by:  Patents (1)
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    For severe intersymbol-interference (ISI) channels, a linear post-equalizer at the receiver causes noise enhancement which degrades the performance. To avoid such a problem we propose the use of adaptive pre-equalization at the transmitter. Based on the back-propagation algorithm used for multi-layer neural networks, we derive an adaptive algorithm to train the pre-equalizer. The simulation example presented shows that substantial power gain can be achieved with this adaptation technique. It is also shown how to extend the training algorithm in order to adapt the pre-equalizer and post-equalizer simultaneously View full abstract»

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  • Maximally fast, bit-serial lattice wave digital filters

    Publication Year: 1996 , Page(s): 207 - 210
    Cited by:  Papers (1)
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    An approach to schedule lattice wave digital filters so that the maximal sample frequency is obtained is presented. In the approach, bit-serial arithmetic and a scheduling method that decouples the sample period from the scheduling period are used. A lower bound on the scheduling period required to arrive at the minimum sample period is given. Different latency models for the arithmetic operations, and their effect on the minimum sample period are discussed. The operation schedule is mapped to a hardware structure using isomorphic mapping. The throughput of the resulting implementations is comparable to corresponding bit-parallel implementations View full abstract»

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  • Breakdown points and optimal soft morphological filtering

    Publication Year: 1996 , Page(s): 490 - 493
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    A novel filter optimality criterion based on the breakdown point constraint is proposed. The criterion provides a trade-off between noise attenuation and detail preservation. The formulas for the breakdown points of the basic soft morphological filters are derived. The practical applicability of the criterion is empirically studied in connection with the optimization of soft morphological filters by simulated annealing and genetic algorithms View full abstract»

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