Now showing items 376-395 of 508

  • Quantization of Sparse Representations 

    Boufounos, Petros T.; Baraniuk, Richard G. (2007-01-16)
    Compressive sensing (CS) is a new signal acquisition technique for sparse and compressible signals. Rather than uniformly sampling the signal, CS computes inner products with randomized basis functions; the signal is then ...
  • Quasi-Circular Rotation Invariance in Image Denoising 

    Wan, Yi; Nowak, Robert David (1999-10-20)
    This paper studies a new method for wavelet-based image denoising which is translation invariant (TI) <b>and</b> rotation invariant (RI). These invariances are crucial in image denoising and, more generally, may play ...
  • Quaternion Wavelets for Image Analysis and Processing 

    Chan, Wai Lam; Choi, Hyeokho; Baraniuk, Richard G. (2004-10-01)
    Using the concepts of two-dimensional Hubert transform and analytic signal, we construct a new quaternion wavelet transform (QWT). The QWT forms a tight frame and can be efficiently computed using a-2-D dual-tree filter ...
  • Queuing analysis of long-range-dependent traffic 

    Ribeiro, Vinay Joseph (1998-04-20)
    None
  • A Radially-Gaussian, Signal-Dependent Time-Frequency Representation 

    Baraniuk, Richard G.; Jones, Douglas L. (1991-04-01)
    An optimization formulation for designing signal-dependent kernels that are based on radially Gaussian functions is presented. The method is based on optimality criteria and is not ad hoc. The procedure is automatic. The ...
  • Random Filters for Compressive Sampling and Reconstruction 

    Baraniuk, Richard G.; Wakin, Michael; Duarte, Marco F.; Tropp, Joel A.; Baron, Dror (2006-05-01)
    We propose and study a new technique for efficiently acquiring and reconstructing signals based on convolution with a fixed FIR filter having random taps. The method is designed for sparse and compressible signals, i.e., ...
  • Random Projections of Signal Manifolds 

    Wakin, Michael; Baraniuk, Richard G. (2006-05-01)
    Random projections have recently found a surprising niche in signal processing. The key revelation is that the relevant structure in a signal can be preserved when that signal is projected onto a small number of random ...
  • Random Projections of Smooth Manifolds 

    Baraniuk, Richard G.; Wakin, Michael (2006-10-01)
    Many types of data and information can be described by concise models that suggest each data vector (or signal) actually has â few degrees of freedomâ relative to its size N. This is the motivation for a variety of ...
  • Rapid Prototyping of Wireless Communications Systems 

    Jones, Bryan Allen (2002-05-20)
    This thesis introduces rapid prototyping methodology which overcomes important barriers in the design and implementation of digital signal processing (DSP) algorithms and systems on embedded hardware platforms, such as ...
  • Rate-constrained Relaying: A Model for Cooperation with Limited Relay Resources 

    Sabharwal, Ashutosh; Mitra, Urbashi (2005-06-01)
    In this paper, the impact of limited resources on achievable rates in relay channels is investigated. Resource limitation is modeled as a rate constraint, Rbar, which constrains the rate at which a relay can reliably ...
  • Rate-Distortion Optimized Image Compression using Wedgelets 

    Wakin, Michael; Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2002-06-01)
    Most wavelet-based image coders fail to model the joint coherent behavior of wavelet coefficients near edges. Wedgelets offer a convenient parameterization for the edges in an image, but they have yet to yield a viable ...
  • Real-Time Algorithms and Architectures for Multiuser Channel Estimation and Detection in Wireless Base-Station Receivers 

    Rajagopal, Sridhar; Bhashyam, Srikrishna; Cavallaro, Joseph R.; Aazhang, Behnaam (2002-07-20)
    This paper presents alogrithms and architecture designs that can meet real-time requirements of multiuser channel estimation and detection in future wireless base-station receivers. Sophisticated algorithms proposed to ...
  • Real-Time DSP Multiprocessor Implementation for Future Wireless Base-Station Receivers 

    Jones, Bryan Allen; Rajagopal, Sridhar; Cavallaro, Joseph R. (2000-08-20)
    The convergence of cellular phones, the Internet, and laptop computers into a single small, lightweight, wireless information appliance drives a need for a high data rate, low-power digital wireless communication link to ...
  • Recent advances in Imaging and Spectroscopy with T-rays 

    Mittleman, Daniel M.; Neelamani, Ramesh; Gupta, Maya; Baraniuk, Richard G.; Nuss, Martin C. (1998-12-01)
    Recent work in terahertz "T-Ray" imaging is reported. With the ongoing development of commercially viable THz-TDS imaging system, opitmail signal processing strategies for the THz waveforms must be developed. Algorithms ...
  • Recent Advances in Terahertz Imaging 

    Koch, Martin; Rudd, J. Van; Neelamani, Ramesh; Gupta, Maya; Baraniuk, Richard G.; Mittleman, Daniel M. (1999-06-01)
    We review recent progress in the field of terahertz "T-ray" imaging. This relatively new imaging technique, based on terahertz time-domain spectroscopy, has the potential to be the first portable far-infared imagin ...
  • RECONSTRUCTION OF SIGNALS FROM PHASE: EFFICIENT ALGORITHMS, SEGMENTATION, AND GENERALIZATIONS 

    MERCHANT, GULAMABBAS ABDULHUSEIN (1982)
    It is well known that the phase of the Fourier transform of a signal contains a significant amount of information about the signal. Under certain circumstances the knowledge of phase is sufficient to recover the original ...
  • A recursive algorithm for digital Image Processing using Local Statistics 

    de Figueiredo, Rui J.P. (1979-06-20)
    An algorithm is presented for digital image processing based on local statistics. The algorithm constitutes a recursive implementaiton of an approach proposed and implemented nonrecursively by J.S. Lee (Naval Research ...
  • Regression level set estimation via cost-sensitive classification 

    Scott, Clayton D.; Davenport, Mark A. (2007-06-01)
    Regression level set estimation is an important yet understudied learning task. It lies somewhere between regression function estimation and traditional binary classification, and in many cases is a more appropriate setting ...
  • Remembering John Napier and His Logarithms 

    Lexa, Michael (2002-05-20)
    This article describes John Napier's original defintion of logarithms and presents his method of tabulation for the first logarithmic table. Napier's logarithms are found to have an intimate relationship with the natural ...
  • Representation and Compression of Multi-Dimensional Piecewise Functions Using Surflets 

    Chandrasekaran, Venkat; Wakin, Michael; Baron, Dror; Baraniuk, Richard G. (2006-03-01)
    We study the representation, approximation, and compression of functions in M dimensions that consist of constant or smooth regions separated by smooth (M-1)-dimensional discontinuities. Examples include images containing ...