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Signal Processing Letters, IEEE

Issue 6 • Date June 2000

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Displaying Results 1 - 11 of 11
  • A new image segmentation method based on human brightness perception and foveal adaptation

    Page(s): 129 - 131
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    We propose an algorithm for adaptive image segmentation based on human psychovisual phenomena: visual perception-based segmentation. The new method can reliably segment poor quality images with low contrast and low SNRs. Due to its adaptability, it can be applied to a wide range of low quality images with different object sizes. In successful tests with ultrasound and flow field images that are normally difficult to segment, this new method outperforms a conventional texture-based segmentation method as a result of its biological source. View full abstract»

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  • A high quality 2 x image interpolator

    Page(s): 132 - 134
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (182 KB)  

    In this paper, we present an innovative interpolator that performs high quality 2/spl times/interpolation on both synthetic and real world images. Its structure, which is based on a rational operator, provides edge-sensitive data interpolation so that sharp- and artifacts-free images are obtained at a reasonable computational cost. View full abstract»

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  • A segmental-feature HMM for speech pattern modeling

    Page(s): 135 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (61 KB)  

    In this letter, we propose a new trajectory model for characterizing segmental features and their interaction based upon a general framework of hidden Markov models. Each segment, a sequence of frame vectors, is represented by a trajectory of observed vector sequences. This trajectory replaces the frame features in the segment and becomes the input of the segmental hidden Markov models (HMM's). In our approach, we adopt polynomial trajectory modeling to represent the trajectories using a new design matrix that includes transitional information on neighborhood acoustic events. To apply this trajectory to the segmental HMM, extra- and intrasegmental variations are modified to contain trajectory information. The presented model is regarded as an extension and generalization of conventional HMM, trajectory-based segmental HMM, and parametric trajectory models. The experimental results are reported on the TIMIT corpus and performance is shown to improve significantly over that of the conventional HMM. View full abstract»

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  • The spatial ambiguity function and its applications

    Page(s): 138 - 140
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (50 KB)  

    This letter introduces the spatial ambiguity functions (SAFs) and discusses their applications to direction finding and source separation problems. We emphasize two properties of SAFs that make them an attractive tool for array signal processing. View full abstract»

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  • The binDCT: fast multiplierless approximation of the DCT

    Page(s): 141 - 144
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (94 KB)  

    This paper presents a family of fast biorthogonal block transforms called binDCT that can be implemented using only shift and add operations. The transform is based on a VLSI-friendly lattice structure that robustly enforces both linear phase and perfect reconstruction properties. The lattice coefficients are parameterized as a series of dyadic lifting steps providing fast, efficient, in place computation of the transform coefficients as well as the ability to map integers to integers. The new 8/spl times/8 transforms all approximate the popular 8/spl times/8 DCT closely, attaining a coding gain range of 8.77-8.82 dB, despite requiring as low as 14 shifts and 31 additions per eight input samples. Application of the binDCT in both lossy and lossless image coding yields very competitive results compared to the performance of the original floating-point DCT. View full abstract»

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  • The LiftLT: fast-lapped transforms via lifting steps

    Page(s): 145 - 148
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    This paper introduces a class of multiband linear phase-lapped biorthogonal transforms with fast, VLSI-friendly implementations via lifting steps called the LiftLT. The transform is based on a lattice structure that robustly enforces both linear phase and perfect reconstruction properties. The lattice coefficients are parameterized as a series of lifting steps, providing fast, efficient, in-place computation of the transform coefficients. The new transform is designed for applications in image and video coding. Compared to the popular 8/spl times/8 DCT, the 8/spl times/16 LiftLT only requires one more multiplication, 22 more additions, and six more shifting operations. However, image coding examples show that the LiftLT is far superior to the DCT in both objective and subjective coding performance. Thanks to properly designed overlapping basis functions, the LiftLT can completely eliminate annoying blocking artifacts. In fact, the novel LT's coding performance consistently surpasses that of the much more complex 9/7-tap biorthogonal wavelet with floating-point coefficients. More importantly, the transform's block-based nature facilitates one-pass sequential block coding, region-of-interest coding/decoding, and parallel processing. View full abstract»

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  • Closed-form design and efficient implementation of generalized maximally flat half-band FIR filters

    Page(s): 149 - 151
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (55 KB)  

    In this letter, a closed-form expression for the impulse response of the generalized half-band (HB) maximally flat (MF) FIR filters is obtained by solving the linear equations of the MF conditions. Based on the resultant impulse responses, an efficient implementation structure is derived. The dynamic range of the multipliers of the new structure is shown to be greatly reduced in comparison to the one of the direct form impulse response. View full abstract»

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  • Wideband direction-of-arrival estimation of multiple chirp signals using spatial time-frequency distributions

    Page(s): 152 - 155
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    The recently developed concept of narrowband spatial time-frequency distributions (STFDs) is extended to the wide-band case. A new STFD-based wideband root-MUSIC estimator is proposed. This technique employs an extended coherent signal-subspace (CSS) principle involving coherent averaging over a pre-selected set of time-frequency points rather than the conventional frequency-only averaging procedure. View full abstract»

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  • Instantaneous kurtosis

    Page(s): 156 - 159
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (86 KB)  

    We introduce the concept of the instantaneous kurtosis of a signal. Using the general approach of Cohen (1993), we obtain an explicit expression in terms of the amplitude and phase of the signal. The idea and results are analogous to those of the instantaneous frequency and the instantaneous bandwidth of a signal, which are low-order conditional moments of the time-varying spectral density of the signal. View full abstract»

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  • Estimation of a Bernoulli parameter p from imperfect trials

    Page(s): 160 - 163
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (95 KB)  

    Imperfect Bernoulli trials arise when the outcome of a Bernoulli experiment is not known with certainty. In signal processing, we often need to estimate a probability of occurrence p of an event from imperfect Bernoulli trials. A typical example is the estimation of the probability of a signal being present in noisy data. In his famous essay, Bayes solved the same problem but for perfect trials. In this letter, a solution is provided for imperfect trials. It is shown that it includes Bayes' solution as a special case. View full abstract»

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  • Two-dimensional lattice linear prediction parameter estimation method and fast algorithm

    Page(s): 164 - 168
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (193 KB)  

    This paper presents an extension of the one-dimensional (1-D) lattice (reflection coefficient) technique of linear prediction parameter estimation, first popularized by Burg, to the two-dimensional (2-D) case. The resulting fast recursive 2-D algorithm is a significant computational simplification over and an estimation improvement on previous attempts to extend the 1-D Burg linear prediction algorithm to 2-D by exploiting some newly discovered matrix structures. The technique presented here is useful for high resolution 2-D spectral analysis applications and the creation of high-resolution spotlight-mode synthetic aperture radar (SAR) imagery, as is illustrated. 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
Peter Willett
University of Connecticut
Storrs, CT 06269
peter.willett@uconn.edu