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IEEE Signal Processing Letters

Issue 5 • May 2001

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Displaying Results 1 - 10 of 10
  • Image denoising using a local contextual hidden Markov model in the wavelet domain

    Publication Year: 2001, Page(s):125 - 128
    Cited by:  Papers (91)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (103 KB) | HTML iconHTML

    Wavelet domain hidden Markov models (HMMs) have been proposed and applied to image processing, e.g., image denoising. We develop a new HMM, called local contextual HMM (LCHMM), by introducing the Gaussian mixture field where wavelet coefficients are assumed to locally follow the Gaussian mixture distributions determined by their neighborhoods. The LCHMM can exploit both the local statistics and th... View full abstract»

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  • An improved search algorithm for motion estimation using adaptive search order

    Publication Year: 2001, Page(s):129 - 130
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (39 KB) | HTML iconHTML

    An adaptive search order (ASO) algorithm is presented to speed up the block motion estimation in digital video coding. According to the motion trend, a table of the adaptive search order is defined. For each searching iteration, a better search order is derived and then the best matched block can be found in the early search stage. Some experimental results demonstrate the computational advantage ... View full abstract»

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  • Model-based MCE bound to the true Bayes' error

    Publication Year: 2001, Page(s):131 - 133
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (60 KB) | HTML iconHTML

    We show that the minimum classification error (MCE) criterion gives an upper bound to the true Bayes' error rate independent of the corresponding model distribution. In addition, we show that model-free optimization of the MCE criterion leads to a closed form solution in the asymptotic case of infinite training data. While leading to the Bayes' error rate, the resulting model distribution differs ... View full abstract»

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  • Multiwarping for enhancing the frequency accuracy of digital waveguide mesh simulations

    Publication Year: 2001, Page(s):134 - 136
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (47 KB) | HTML iconHTML

    A multiwarping technique is introduced. The method is based on cascading frequency warping procedures and sample rate conversions. As a practical example, we show that with this new approach, the maximal frequency error of digital waveguide mesh simulations can be reduced by about 50%. This technique gives more degrees of freedom to attain a desired amount of nonlinear frequency shift still applyi... View full abstract»

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  • A data-adaptive knot selection scheme for fitting splines

    Publication Year: 2001, Page(s):137 - 139
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (61 KB) | HTML iconHTML

    A critical component of spline smoothing is the choice of knots, especially for curves with varying shapes and frequencies in its domain. We consider a two-stage knot selection scheme for adaptively fitting splines to data subject to noise. A potential set of knots is chosen based on information from certain wavelet decompositions with the intention of placing more points where the curve shows rap... View full abstract»

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  • Parametric TFR via windowed exponential frequency modulated atoms

    Publication Year: 2001, Page(s):140 - 142
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (114 KB) | HTML iconHTML

    We propose a new atom, namely, the dilated and translated windowed exponential frequency modulated functions (FM/sup m/let) for compactly characterizing both the signal's time-invariant and time-varying spectral contents. The superiority of the proposed method to some existing time-frequency distributions (TFDs) is demonstrated using a bat sonar signal. View full abstract»

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  • Distortion analysis for multiplierless sampling rate conversion using linear transfer functions

    Publication Year: 2001, Page(s):143 - 144
    Cited by:  Papers (3)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (37 KB) | HTML iconHTML

    Approximation techniques simplify sampling rate conversion with a rational ratio. The multiplierless approach, also known as zero-order polynomial interpolation, drops or repeats selected samples of the input sequence. Previous distortion analyses are based either on the time domain sample error or the frequency transform of the output sequence. Our new approach shows that any approximate conversi... View full abstract»

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  • An extended split-radix FFT algorithm

    Publication Year: 2001, Page(s):145 - 147
    Cited by:  Papers (49)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (97 KB) | HTML iconHTML

    An extended split-radix fast Fourier transform (FFT) algorithm is proposed. The extended split-radix FFT algorithm has the same asymptotic arithmetic complexity as the conventional split-radix FFT algorithm. Moreover, this algorithm has the advantage of fewer loads and stores than either the conventional split-radix FFT algorithm or the radix-4 FFT algorithm. View full abstract»

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  • The stochastic CRB for array processing: a textbook derivation

    Publication Year: 2001, Page(s):148 - 150
    Cited by:  Papers (115)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (79 KB) | HTML iconHTML

    The stochastic Cramer-Rao bound (CRB) for direction estimation in array processing applications was indirectly derived some ten years ago as the (asymptotic) covariance matrix of the maximum likelihood (ML) estimator. Attempts to obtain the stochastic CRB directly via the CRB theory fell short of providing a simple derivation and consequently, no direct derivation of this useful performance bound ... View full abstract»

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  • Simulation of dependent samples of symmetric alpha-stable clutter

    Publication Year: 2001, Page(s):151 - 152
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (44 KB) | HTML iconHTML

    Discrete-time samples of isotropic clutter with symmetric alpha-stable (S/spl alpha/S) distribution are generated by modulating a complex correlated Gaussian sequence with a nonnegative sequence with skewed stable distribution. The quadrature components of such simulated clutter are uncorrelated, yet dependent, with uniform phase. The statistical dependence between samples of the modulating sequen... View full abstract»

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Aims & Scope

The IEEE Signal Processing Letters is a monthly, archival publication designed to provide rapid dissemination of original, cutting-edge ideas and timely, significant contributions in signal, image, speech, language and audio processing.

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Meet Our Editors

Editor-in-Chief
James E. Fowler
Dept Electrical & Computer Engineering
Associate Director                         
Distributed Analytics and Security Institute
Mississippi State University
Mississippi State, MS 39762 USA
fowler@ece.msstate.edu