Now showing items 1-60 of 244

  • An Adaptive Optimal-Kernel Time-Frequency Representation 

    Jones, Douglas L.; Baraniuk, Richard G. (1995-10-01)
    Time-frequency representations with fixed windows or kernels figure prominently in many applications, but perform well only for limited classes of signals. Representations with signal- dependent kernels can overcome this ...
  • Adaptive Wavelet Transforms for Image Coding 

    Claypoole, Roger L.; Davis, Geoffrey; Sweldens, Wim; Baraniuk, Richard G. (1997-11-01)
    We introduce a new adaptive transform for wavelet-based image coding. The lifting framework for wavelet construction motivates our analysis and provides new insight into the problem. Since the adaptive transform is non-linear, ...
  • Adaptive Wavelet Transforms for Image Coding 

    Claypoole, Roger L.; Davis, Geoffrey; Sweldens, Wim; Baraniuk, Richard G. (1997-11-01)
    We introduce a new adaptive transform for wavelet-based image coding. The lifting framework for wavelet construction motivates our analysis and provides new insight into the problem. Since the adaptive transform is non-linear, ...
  • Adaptive Wavelet Transforms for Image Coding using Lifting 

    Claypoole, Roger L.; Davis, Geoffrey; Sweldens, Wim; Baraniuk, Richard G. (1998-03-01)
    Summary form only given. Image compression relies on efficient representations of images, and within smooth image regions, the wavelet transform provides such a representation. However, near edges, wavelet coefficients ...
  • Adaptive Wavelet Transforms via Lifting 

    Claypoole, Roger L.; Baraniuk, Richard G.; Nowak, Robert David (1998-05-01)
    This paper develops two new adaptive wavelet transforms based on the lifting scheme. The lifting construction exploits a spatial-domain, prediction-error interpretation of the wavelet transform and provides a powerful ...
  • Adaptive Wavelet Transforms via Lifting 

    Claypoole, Roger L.; Baraniuk, Richard G.; Nowak, Robert David (1999-01-15)
    This paper develops new algorithms for adapted multiscale analysis and signal adaptive wavelet transforms. We construct our adaptive transforms with the <i>lifting scheme</i>, which decomposes the wavelet transform into ...
  • Adaptive Wavelet Transforms via Lifting 

    Claypoole, Roger L.; Baraniuk, Richard G.; Nowak, Robert David (1999-05-01)
    This paper develops new algorithms for adapted multiscale analysis and signal adaptive wavelet transforms. We construct our adaptive transforms with the <i>lifting scheme</i>, which decomposes the wavelet transform into ...
  • Adaptive Weighted Highpass Filters Using Multiscale Analysis 

    Nowak, Robert David; Baraniuk, Richard G. (1998-07-01)
    In this paper, we propose a general framework for studying a class of weighted highpass filters. Our framework, based on a multiscale signal decomposition, allows us to study a wide class of filters and to assess the ...
  • Additive and Multiplicative Mixture Trees for Network Traffic Modeling 

    Sarvotham, Shriram; Wang, Xuguang; Riedi, Rudolf H.; Baraniuk, Richard G. (2002-05-01)
    Network traffic exhibits drastically different statistics, ranging from nearly Gaussian marginals and long range dependence at very large time scales to highly non-Gaussian marginals and multifractal scaling on small scales. ...
  • Analysis of Multiscale Texture Segmentation using Wavelet-Domain Hidden Markov Trees 

    Choi, Hyeokho; Hendricks, Brent; Baraniuk, Richard G. (1999-10-01)
    This paper describes a technique for estimating the Kullback-Leibler (KL) distance between two Hidden Markov Models (HMMs), and for measuring the quality of the estimator. It also provides some results based on applying ...
  • Analysis of the DCS one-stage Greedy Algorothm for Common Sparse Supports 

    Baron, Dror; Duarte, Marco F.; Wakin, Michael; Sarvotham, Shriram; Baraniuk, Richard G. (2005-11-01)
    Analysis of the DCS one-stage Greedy Algorothm for Common Sparse Supports
  • Analysis of Wavelet domain Wiener Filters 

    Choi, Hyeokho; Baraniuk, Richard G. (1998-10-01)
    We investigate Wiener filtering of wavelet coefficients for signal denoising. Empirically designed wavelet-domain Wiener filters outperform many other denoising algorithms based on wavelet thresholding. However, up to now, ...
  • Applications of Adaptive Time Frequency Representations to Underwater Acoustic Signal Processing 

    Baraniuk, Richard G.; Jones, Douglas L.; Tom, Brotherton; Larry, Marple (1991-11-01)
    The authors describe the application of an adaptive optimal kernel (AOK) time-frequency representation to the processing of underwater acoustic data. The optimal kernel is a signal-dependent radially Gaussian function. ...
  • Applications of Terahertz Imaging 

    Mittleman, Daniel M.; Neelamani, Ramesh; Baraniuk, Richard G.; Nuss, Martin C. (1998-08-01)
    The recent advances involving imaging with sub-picosecond terahertz pulses have opened up a wide range of possibilities in the applications of far-infrared technology. For the first time, a commercially viable terahertz ...
  • Approximation and Compression of Piecewise Smooth Images Using a Wavelet/Wedgelet Geometric Model 

    Romberg, Justin; Wakin, Michael; Baraniuk, Richard G. (2003-09-01)
    Inherent to photograph-like images are two types of structures: large smooth regions and geometrically smooth edge contours separating those regions. Over the past years, efficient representations and algorithms have been ...
  • An Architecture for Distributed Wavelet Analysis and Processing in Sensor Networks 

    Wagner, Raymond; Baraniuk, Richard G.; Du, Shu; Johnson, David B.; Cohen, Albert (2006-04-01)
    Distributed wavelet processing within sensor networks holds promise for reducing communication energy and wireless bandwidth usage at sensor nodes. Local collaboration among nodes de-correlates measurements, yielding a ...
  • Asymptotic Performance of Transmit Diversity via OFDM for Multipath Channels 

    Ahmed, Nadeem; Baraniuk, Richard G. (2002-11-01)
    Many wireless systems exploit transmit diversity for more reliable detection of signals at the receiver. To accomplish this, coding is spread across multiple transmit antennas. An example of this is the well known "Alamouti ...
  • Bayesian Tree-Structured Image Modeling 

    Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2000-04-01)
    Wavelet-domain hidden Markov models have proven to be useful tools for statistical signal and image processing. The hidden Markov tree (HMT) model captures the key features of the joint statistics of the wavelet coefficients ...
  • Bayesian Tree-Structured Image Modeling using Wavelet-domain Hidden Markov Models 

    Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2001-07-01)
    Wavelet-domain hidden Markov models have proven to be useful tools for statistical signal and image processing. The hidden Markov tree (HMT) model captures the key features of the joint probability density of the wavelet ...
  • Bayesian Tree-Structured Image Modeling using Wavelet-domain Hidden Markov Models 

    Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (1999-07-20)
    Wavelet-domain hidden Markov models have proven to be useful tools for statistical signal and image processing. The hidden Markov tree (HMT) model captures the key features of the joint probability density of the wavelet ...
  • Bayesian Wavelet Domain Image Modeling using Hidden Markov Trees 

    Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (1999-10-01)
    Wavelet-domain hidden Markov models have proven to be useful tools for statiscal signal and image processing. The hidden Markov tree (HMT) model captures the key features o teh join statistics of the wavelet coefficients ...
  • Beyond Time Frequency Analysis: Energy Densities in One and Many Dimensions 

    Baraniuk, Richard G. (1994-04-01)
    Given a unitary operator <i>A</i> representing a physical quantity of interest, we employ concepts from group representation theory to define two natural signal energy densities for <i>A</i>. The first is invariant to ...
  • Beyond Time Frequency Analysis: Energy Densities in One and Many Dimensions 

    Baraniuk, Richard G. (1998-09-01)
    Given a unitary operator A representing a physical quantity of interest, we employ concepts from group representation theory to define two natural signal energy densities for A. The first is invariant to A and proves ...
  • Blind Crosstalk Cancellation for DMT Systems 

    Ahmed, Nadeem; Warke, Nirmal; Baraniuk, Richard G. (2002-09-01)
    As the deployment of broadband communication systems such as DSL continues to grow, system performance in terms of capacity and error rates is severely limited by crosstalk interference. In order to continue deploying high ...
  • Coherent Image Processing using Quaternion Wavelets 

    Chan, Wai Lam; Choi, Hyeokho; Baraniuk, Richard G. (2005-08-01)
    We develop a quaternion wavelet transform (QWT) as a new multiscale analysis tool for geometric image features. The QWT is a near shift-invariant, tight frame representation whose coefficients sport a magnitude and three ...
  • Coherent Multiscale Image Processing using Quaternion Wavelets 

    Chan, Wai Lam; Choi, Hyeokho; Baraniuk, Richard G. (2006-10-01)
    The quaternion wavelet transform (QWT) is a new multiscale analysis tool for geometric image features. The QWT is a near shift-invariant tight frame representation whose coefficients sport a magnitude and three phases: ...
  • Community Driven Digital Signal Processing Laboratories in Connexions 

    Baraniuk, Richard G.; Choi, Hyeokho; Jones, Douglas L.; Potter, Lee (2004-06-01)
    The conventional textbook is largely inadequate for digital signal processing (DSP) laboratory education due to inherent factors such as a small and fragmented market and rapid hardware obsolescence. Freely available ...
  • Compressing Piecewise Smooth Multidimensional Functions Using Surflets: Rate-Distortion Analysis 

    Chandrasekaran, Venkat; Wakin, Michael; Baron, Dror; Baraniuk, Richard G. (2004-03-01)
    Discontinuities in data often represent the key information of interest. Efficient representations for such discontinuities are important for many signal processing applications, including compression, but standard Fourier ...
  • Compression Color Space Estimation of JPEG Images using Lattice Basis Reduction 

    Neelamani, Ramesh; Baraniuk, Richard G.; de Queiroz, Ricardo (2001-10-01)
    Given a color image that was previously JPEG-compressed in some hidden color space, we aim to estimate this unknown compression color space from the image. This knowledge is potentially useful for color image enhancement ...
  • Compression of Higher Dimensional Functions Containing Smooth Discontinuities 

    Chandrasekaran, Venkat; Wakin, Michael; Baron, Dror; Baraniuk, Richard G. (2004-03-01)
    Discontinuities in data often represent the key information of interest. Efficient representations for such discontinuities are important for many signal processing applications, including compression, but standard Fourier ...
  • Connection-level Analysis and Modeling of Network Traffic 

    Sarvotham, Shriram; Riedi, Rudolf H.; Baraniuk, Richard G. (2001-11-01)
    Most network traffic analysis and modeling studies lump all connections together into a single flow. Such aggregate traffic typically exhibits long-range-dependent (LRD) correlations and non-Gaussian marginal distributions. ...
  • The Connexions Project: Promoting Open Sharing of Knowledge for Education 

    Henry, Geneva; Baraniuk, Richard G.; Kelty, Christopher (2003-07-01)
    The Connexions project at Rice University has created an open repository of educational materials and tools to promote sharing and exploration of knowledge as a dynamic continuum of interrelated concepts. Available free ...
  • Connexions: DSP Education for a Networked World 

    Baraniuk, Richard G. (2002-05-01)
    Connexions is a new approach to authoring, teaching, and learning that aims to fully exploit modern information technology. Available free of charge to anyone under open-content and open-source licenses, Connexions offers ...
  • Contextual Hidden Markov Models for Wavelet-domain Signal Processing 

    Crouse, Matthew; Baraniuk, Richard G. (1997-11-01)
    Wavelet-domain hidden Markov models (HMMs) provide a powerful new approach for statistical modeling and processing of wavelet coefficients. In addition to characterizing the statistics of individual wavelet coefficients, ...
  • Contraction, Smoothness, and Low-Pass Filtering 

    Khojastepour, Mohammad; Aazhang, Behnaam; Baraniuk, Richard G. (2004-05-01)
    We introduce a generalized definition for "low-pass" filters that covers time-varying and nonlinear systems under the same umbrella. We show that the qualitative concept of signal smoothing can be made precise through the ...
  • Controlling False Alarms with Support Vector Machines 

    Davenport, Mark A.; Baraniuk, Richard G.; Scott, Clayton D. (2006-05-01)
    We study the problem of designing support vector classifiers with respect to a Neyman-Pearson criterion. Specifically, given a user-specified level alpha, 0 < alpha < 1, how can we ensure a false alarm rate no greater than ...
  • Covariant Time Frequency Representations Through Unitary Equivalence 

    Baraniuk, Richard G. (1996-03-01)
    We propose a straightforward characterization of all quadratic time-frequency representations covariant to an important class of unitary signal transforms (namely, those having two continuous-valued parameters and an ...
  • Delay-Limited Throughput Maximization for Fading Channels using Rate and Power Control 

    Ahmed, Nadeem; Khojestapour, Mohammad; Baraniuk, Richard G. (2004-12-01)
    The fading channels seen in many wireless systems provide a particularly hostile environment for reliable communication. Current metrics for evaluating the performance limits of fading channels have shortcomings. Ergodic ...
  • Design of Adaptive Overlays for Multi-scale Communication in Sensor Networks 

    PalChaudhuri, Santashil; Kumar, Rajnish; Baraniuk, Richard G.; Johnson, David B. (2005-06-01)
    In wireless sensor networks, energy and communication bandwidth are precious resources. Traditionally, layering has been used as a design principle for network stacks; hence routing protocols assume no knowledge of the ...
  • Detection and estimation with compressive measurements 

    Baraniuk, Richard G.; Davenport, Mark A.; Wakin, Michael B. (2006-11-01)
    The recently introduced theory of compressed sensing enables the reconstruction of sparse or compressible signals from a small set of nonadaptive, linear measurements. If properly chosen, the number of measurements can ...
  • Directional Hypercomplex Wavelets for Multidimensional Signal Analysis and Processing 

    Chan, Wai Lam; Choi, Hyeokho; Baraniuk, Richard G. (2004-05-01)
    We extend the wavelet transform to handle multidimensional signals that are smooth save for singularities along lower-dimensional manifolds. We first generalize the complex wavelet transform to higher dimensions using a ...
  • Directional Scale Analysis for Seismic Interpretation 

    van Spaendonck, Rutger; Baraniuk, Richard G. (1999-11-01)
    A combined space-Fourier representation focused on directional scale analysis is presented. The method leads to a space-log polar frequency distribution. Application to seismic data shows differentiation in scale and ...
  • Distributed Camera Network Localization 

    Mantzel, William; Choi, Hyeokho; Baraniuk, Richard G. (2004-11-01)
    Localization, estimating the positions and orientations of a set of cameras, is a critical first step in camera-based sensor network applications such as geometric estimation, scene reconstruction, and motion tracking. We ...
  • Distributed Compressed Sensing of Jointly Sparse Signals 

    Sarvotham, Shriram; Baron, Dror; Wakin, Michael; Duarte, Marco F.; Baraniuk, Richard G. (2005-11-01)
    Compressed sensing is an emerging field based on the revelation that a small collection of linear projections of a sparse signal contains enough information for reconstruction. In this paper we expand our theory for ...
  • Distributed Image Compression for Sensor Networks using Correspondence Analysis and Super-Resolution 

    Wagner, Raymond; Nowak, Robert David; Baraniuk, Richard G. (2003-09-01)
    We outline a distributed coding technique for images captured from sensors with overlapping fields of view in a sensor network. First, images from correlated views are roughly registered (relative to a sensor of primary ...
  • Distributed Multiscale Data Analysis and Processing for Sensor Networks 

    Wagner, Raymond; Sarvotham, Shriram; Choi, Hyeokho; Baraniuk, Richard G. (2005-02-01)
    While multiresolution data analysis, processing, and compression hold considerable promise for sensor network applications, progress has been confounded by two factors. First, typical sensor data are irregularly spaced, ...
  • Distributed Wavelet Transform for Irregular Sensor Network Grids 

    Wagner, Raymond; Choi, Hyeokho; Baraniuk, Richard G.; Delouille, Veronique (2005-07-01)
    Wavelet-based distributed data processing holds much promise for sensor networks; however, irregular sensor node placement precludes the direct application of standard wavelet techniques. In this paper, we develop a new ...
  • DSP Education At Rice University 

    Frantz, Patrick; Choi, Hyeokho; Baraniuk, Richard G. (2003-09-01)
    Rice University has a decades-long tradition of both digital signal processing (DSP) research and education, beginning in 1968. Since that time, Rice University has become a world leader and continued to be a pioneer in ...
  • The Dual-Tree Complex Wavelet Transform 

    Selesnick, Ivan W.; Baraniuk, Richard G.; Kingsbury, Nicholas G. (2005-11-01)
    The paper discusses the theory behind the dual-tree transform, shows how complex wavelets with good properties can be designed, and illustrates a range of applications in signal and image processing. The authors use the ...
  • Edge Localized Image Sharpening via Reassignment with Application to Computed Tomography 

    Dorney, Timothy D.; Bhashyam, Srikrishna; Doran, Andrew; Choi, Hyeokho; Flandrin, Patrick; Baraniuk, Richard G. (2000-07-01)
    Traditional filtering methods operate on the entire signal or image. In some applications, however, errors are concentrated in specific regions or features. A prime example is images generated using computed tomography. ...
  • Efficient Approximation of Continuous Wavelet Transforms 

    Jones, Douglas L.; Baraniuk, Richard G. (1991-04-01)
    An efficient method, based on the chirp-z transform, for computing equally spaced time samples of a continuous wavelet transform at arbitrary scale samples is developed. Applications include efficient computation of samples ...
  • The Embedded Triangles Algorithm for Distributed Estimation in Sensor Networks 

    Delouille, Veronique; Neelamani, Ramesh; Chandrasekaran, Venkat; Baraniuk, Richard G. (2003-09-01)
    We propose a new iterative distributed estimation algorithm for Gaussian hidden Markov graphical models with loops. We decompose a loopy graph into a number of linked <i>embedded triangles</i> and then apply a parallel ...
  • Empirical Mode Decomposition Based Frequency Attributes 

    Magrin-Chagnolleau, Ivan; Baraniuk, Richard G. (1999-11-01)
    This paper describes a new technique, called <i>Empirical Mode Decomposition</i> (EMD), which allows the decomposition of one-dimensional signals into intrinsic oscillatory modes. Each component, called <i>Intrinsic Mode ...
  • Estimation-Quantization Geometry Coding Using Normal Meshes 

    Lavu, Sridhar; Choi, Hyeokho; Baraniuk, Richard G. (2003-03-01)
    We propose a new algorithm for compressing three-dimensional triangular mesh data used for representing surfaces. We apply the Estimation-Quantization (EQ) algorithm originally designed for still image compression to the ...
  • Fast, Exact Synthesis of Gaussian and nonGaussian Long-Range-Dependent Processes 

    Crouse, Matthew; Baraniuk, Richard G. (1999-01-15)
    1/<i>f</i> noise and statistically self-similar processes such as fractional Brownian motion (fBm) are vital for modeling numerous real-world phenomena, from network traffic to DNA to the stock market. Although several ...
  • Faster Sequential Universal Coding via Block Partitioning 

    Baron, Dror; Baraniuk, Richard G. (2006-04-01)
    Rissanen provided a sequential universal coding algorithm based on a block partitioning scheme, where the source model is estimated at the beginning of each block. This approach asymptotically approaches the entropy at the ...
  • Flexible Wavelet Transforms Using Lifting 

    Claypoole, Roger L.; Baraniuk, Richard G. (1998-09-01)
    We introduce and discuss biorthogonal wavelet transforms using the lifting construction. The lifting construction exploits a spatial-domain, prediction-error interpretation of the wavelet transform and provides a powerful ...
  • ForWaRD: Fourier-Wavelet Regularized Deconvolution for Ill-Conditioned Systems 

    Neelamani, Ramesh; Choi, Hyeokho; Baraniuk, Richard G. (2004-02-01)
    We propose an efficient, hybrid <i>Fourier-Wavelet Regularized Deconvolution</i> (ForWaRD) algorithm that performs noise regularization via scalar shrinkage in both the Fourier and wavelet domains. The Fourier shrinkage ...
  • Gas Sensing using Terahertz Time-Domain Spectroscopy 

    Mittleman, Daniel M.; Jacobsen, R. H.; Neelamani, Ramesh; Baraniuk, Richard G.; Nuss, Martin C. (1998-01-15)
    A method for detection and identification of polar gases and gas mixtures based on the technique of terahertz time-domain spectroscopy is presented. This relatively new technology promises to be the first portable far-infared ...
  • A Geometric Hidden Markov Tree Wavelet Model 

    Romberg, Justin; Wakin, Michael; Choi, Hyeokho; Baraniuk, Richard G. (2003-08-01)
    In the last few years, it has become apparent that traditional wavelet-based image processing algorithms and models have significant shortcomings in their treatment of edge contours. The standard modeling paradigm exploits ...