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

作者： I. Sodagar K. Nayebi T.P. Barnwell M.J.T. Smith Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

Perfect reconstruction (PR) time-varying analysis-synthesis filter banks are those in which the filters are allowed to change from one set of PR filter banks to another as the input signal is being processed. Such systems have the property that, in the absence of coding, they faithfully reconstruct every sample of the input. This paper introduces a new structure for exact reconstructing time-varying analysis-synthesis filter banks. This structure consists of the conventional filter bank followed by a time-varying post filter. The new method requires neither the redesign of the analysis sections, nor the use of any intermediate analysis filters during transition periods. It provides a simple procedure for designing time-varying filter banks without the disadvantages of the previous methods.< >

关键词： Finite impulse response filter Filter bank Time frequency analysis Channel bank filters Digital signal processing Laboratories signal analysis Digital filters signal processing signal synthesis

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Image coding using high-order conditional entropy-constrained residual VQ

Image coding using high-order conditional entropy-constraine...

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IEEE International Conference on Image processing

作者： F. Kossentini W.C. Chung M.J.T. Smith Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

An extension of entropy-constrained residual vector quantization is presented where inter-vector dependencies are exploited. The method, which the authors call conditional entropy-constrained residual vector quantization, employs a high-order entropy conditioning strategy that captures local information in the neighboring vectors. The complexity of the proposed design algorithm is relatively low, due mainly to the efficiency of the multistage structure of the residual vector quantizer, but also to the effectiveness of the searching techniques used to locate the best conditioning spatial-stage region of support. Experimental results show that the new method outperforms standard entropy-constrained residual vector quantization while also requiring lower encoding complexity and memory requirements.< >

关键词： Image coding Vector quantization Entropy Bit rate Digital signal processing Laboratories Algorithm design and analysis signal processing algorithms Optimization methods Probability

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Preprocessing for noise reduction of chaotic signals

Preprocessing for noise reduction of chaotic signals

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IEEE Digital signal processing Workshop

作者： Chungyong Lee D.B. Williams Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

ISBN: (纸本)0780319486

Existing algorithms for filtering noise from contaminated chaotic signals require relatively high signal-to-noise ratios (SNRs). A preprocessing method is proposed for initial noise reduction in severe SNRs. This method uses all the difference vectors between the points in a small neighborhood of the point of interest to estimate more accurately the tangent surface described by Cawley and Hsu (1992). This preprocessing method is applicable to noisy data from any nonlinear dynamical system, because it does not require knowledge of the system dynamics.< >

关键词： Noise reduction Chaos Chaotic communication Nonlinear dynamical systems signal to noise ratio signal processing algorithms Laboratories signal processing Noise level Digital signal processing

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Low complexity matching criteria for image/video applications

Low complexity matching criteria for image/video application...

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IEEE International Conference on Image processing

作者： M. Khosravi R.W. Schafer Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

The paper extends Kosravi and Schafer (1994) which introduced the notion of normalized min correlation (NMC) as a new criterion for template matching applications. The NMC features low complexity and robustness with respect to Gaussian noise. It is also independent of the local average of the image, which is a desired property in many template matching applications. However, its sensitivity to impulsive noise increases with the size of the template. The paper introduces two different modifications of the NMC which are robust with respect to both Gaussian and impulsive noise. The performance of the new modifications are examined in motion estimation applications. As a different way of looking at the NMC, the notion of grayscale hit-or-miss transform is introduced. This is an extension of the binary hit-or-miss transform to grayscale.< >

关键词： Noise robustness Gaussian noise Application software Gray-scale Linear systems Statistics Digital signal processing Laboratories Motion estimation Digital filters

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A multiple exchange Remez algorithm for complex FIR filter design in the Chebyshev sense

A multiple exchange Remez algorithm for complex FIR filter d...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： L.J. Karam J.H. McClellan Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

The alternation theorem is at the core of the efficient real Chebyshev approximation algorithms. In this paper, the alternation theorem is extended from the real-only to the complex case. A new efficient algorithm is described for designing FIR filters that best approximate in the Chebyshev sense a desired complex-valued function. This algorithm is based on an ascent Remez exchange method applied to a transformation of the complex Chebyshev error, and is basically a generalization of the Parks-McClellan algorithm to the complex case. Numerical examples are presented to illustrate the performance of the proposed algorithm.< >

关键词： Finite impulse response filter Algorithm design and analysis Chebyshev approximation signal processing algorithms Least squares approximation Approximation algorithms Frequency Iterative algorithms signal design Digital signal processing

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Detection of nonstationary random signals in colored noise

Detection of nonstationary random signals in colored noise

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

作者： W.T. Padgett D.B. Williams Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

This paper describes a novel method for detecting nonstationary signals in colored noise. A first order complex autoregressive, or AR(1), signal model is used which restricts the application of the detector to low order signals, i.e., those which are well modeled by a low order AR process and have only a single spectral peak. The detector assumes the noise covariance is stationary and known. The likelihood function is estimated in the frequency domain because the model simplifies, and the nonstationary frequency estimate can be obtained by an algorithm which approximates the Viterbi algorithm. The AR model parameters are then used to form the appropriate covariance matrix and the approximate likelihood is calculated. Therefore, the detector uses efficient approximations to approximate the generalized likelihood ratio test (GLRT). Simulation results are shown to compare the detector with the known signal likelihood ratio test.< >

关键词： Colored noise Detectors Frequency estimation signal processing Testing signal detection signal processing algorithms Maximum likelihood detection Digital signal processing Laboratories

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On the statistically optimum FIR filter bank design

On the statistically optimum FIR filter bank design

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IEEE Digital signal processing Workshop

作者： I. Sodagar T.P. Barnwell M.J.T. Smith School of Electrical and Computer Engineering Digital Signal Processing Laboratory Georgia Institute of Technology Atlanta GA USA

The paper is concerned with the analysis and design of statistically optimum FIR filter banks. In such systems, the analysis/synthesis system and the subband quantizers are designed jointly to provide the minimum distortion in the reconstructed signal. In the paper, a new approach to this problem is introduced. Using the time-domain formulation of Nayebi et al. [1992], the present authors derive a formula for the mean square error (MSE) of the output signal. The resulting formulation provides a general framework for the optimum filter bank design problem and includes previous reported formulations. This approach can be used to design the optimal filter bank and quantizers for a given wide sense stationary signal.< >

关键词： Finite impulse response filter Filter bank signal synthesis Time domain analysis signal analysis signal design Image coding Speech synthesis Bit rate Digital signal processing

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A non-expansive pyramidal morphological image coder

A non-expansive pyramidal morphological image coder

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IEEE International Conference on Image processing

作者： D.A.F. Florencio R.W. Schafer Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

Pyramid image coding is a natural coding scheme for applications where progressive transmission is desired. In this kind of coder, versions of the original image at several resolution levels are formed by successive filtering and subsampling. Then, beginning from the coarsest image, the image is used to produce an estimate for the next (higher resolution) level and the error is coded and transmitted. While expansive pyramids (e.g., Burt's Laplacian pyramid) are usually less efficient, non-expansive pyramids tend to produce ringing (e.g., subband/wavelet) and/or blocking (e.g., DCT). We introduce a non-expansive pyramid that does not, produce ringing or blocking effects. Instead, the main artifact is texture removal. The simulations have produced images with entropies in the range of 0.2 to 1.5 bpp, with SNR figures similar to or better than JPEG at equivalent rates. The proposed coder has several attractive features, including 8 bit integer operations only, a perfect reconstruction mode, progressive transmission and an interesting progressive computation property.< >

关键词： Image resolution Image reconstruction Filters Image coding Filtering Laplace equations Entropy Contracts Sampling methods Digital signal processing

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Time-varying motion estimation using orthogonal polynomials and applications

Time-varying motion estimation using orthogonal polynomials ...

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International Conference on Pattern Recognition

作者： S. Ayer P. Schroeter P. Brigger Electrical Engineering Department Signal Processing Laboratory Swiss Federal Institute of Technology Lausanne Switzerland

This paper presents a hierarchical motion estimation method considering both a large spatial and temporal support. The problem of motion estimation is formulated as a time-varying parameter estimation problem. The main advantage of the proposed algorithm is its ability to constrain the computation of the flow field spatially and temporally at the same time, by defining each motion parameter as a linear combination of some orthogonal time functions. The number of time basis varies according to the complexity of the movement and is determined automatically by means of a multiresolution approach and of statistical tests. We also present two different applications which underline the validity of the chosen approach.

关键词： Motion estimation Polynomials Motion analysis Parameter estimation Image motion analysis Image segmentation Spatial resolution Optical signal processing Optical computing Image sequences

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DISCRIMINATION OF ENVELOPE FREQUENCY IN ONE SPECTRAL REGION IN THE PRESENCE OF MODULATION IN ANOTHER

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JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 1994年第3期96卷 1445-1457页

作者： BUUS, S PAN, C Communication and Digital Signal Processing Center Department of Electrical and Computer Engineering (409 DA) Northeastern University Boston Massachusetts 02115

This paper examines how discrimination of envelope frequency in one spectral region is affected by the presence of either correlated or uncorrelated modulation in another spectral region. Envelope-frequency discrimination thresholds, Delta f(e)'s, for a 60-dB SPL two-tone complex centered at 2 kHz were in the presence or absence of an auxiliary two-tone complex at another frequency. When present, the auxiliary complex had either the same envelope as the standard signal or an envelope that was uncorrelated with both the standard and variable signal. The results show that listeners can take advantage of correlation between simultaneous envelopes in different frequency regions to improve discrimination of a small change in envelope frequency, whereas the presence of uncorrelated envelopes causes interference with discrimination. Except when the auxiliary complex and the signal are close together in frequency, the discrimination advantage afforded by the correlated auxiliaries appears to reflect across-channel envelope processing. The discrimination interference caused by the uncorrelated auxiliaries, on the other hand, may reflect primarily within-channel interaction such as peripheral masking, although a small amount of across-channel masking also is apparent.

关键词： Sound discrimination Sound pressure

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