Browsing George R. Brown School of Engineering by Author "Baraniuk, Richard G."
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An Adaptive OptimalKernel TimeFrequency Representation
Jones, Douglas L.; Baraniuk, Richard G. (19951001)Timefrequency 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. (19971101)We introduce a new adaptive transform for waveletbased image coding. The lifting framework for wavelet construction motivates our analysis and provides new insight into the problem. Since the adaptive transform is nonlinear, ... 
Adaptive Wavelet Transforms for Image Coding
Claypoole, Roger L.; Davis, Geoffrey; Sweldens, Wim; Baraniuk, Richard G. (19971101)We introduce a new adaptive transform for waveletbased image coding. The lifting framework for wavelet construction motivates our analysis and provides new insight into the problem. Since the adaptive transform is nonlinear, ... 
Adaptive Wavelet Transforms for Image Coding using Lifting
Claypoole, Roger L.; Davis, Geoffrey; Sweldens, Wim; Baraniuk, Richard G. (19980301)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 (19980501)This paper develops two new adaptive wavelet transforms based on the lifting scheme. The lifting construction exploits a spatialdomain, predictionerror interpretation of the wavelet transform and provides a powerful ... 
Adaptive Wavelet Transforms via Lifting
Claypoole, Roger L.; Baraniuk, Richard G.; Nowak, Robert David (19990115)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 (19990501)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. (19980701)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. (20020501)Network traffic exhibits drastically different statistics, ranging from nearly Gaussian marginals and long range dependence at very large time scales to highly nonGaussian marginals and multifractal scaling on small scales. ... 
Analysis of Multiscale Texture Segmentation using WaveletDomain Hidden Markov Trees
Choi, Hyeokho; Hendricks, Brent; Baraniuk, Richard G. (19991001)This paper describes a technique for estimating the KullbackLeibler (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 onestage Greedy Algorothm for Common Sparse Supports
Baron, Dror; Duarte, Marco F.; Wakin, Michael; Sarvotham, Shriram; Baraniuk, Richard G. (20051101)Analysis of the DCS onestage Greedy Algorothm for Common Sparse Supports 
Analysis of Wavelet domain Wiener Filters
Choi, Hyeokho; Baraniuk, Richard G. (19981001)We investigate Wiener filtering of wavelet coefficients for signal denoising. Empirically designed waveletdomain 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 (19911101)The authors describe the application of an adaptive optimal kernel (AOK) timefrequency representation to the processing of underwater acoustic data. The optimal kernel is a signaldependent radially Gaussian function. ... 
Applications of Terahertz Imaging
Mittleman, Daniel M.; Neelamani, Ramesh; Baraniuk, Richard G.; Nuss, Martin C. (19980801)The recent advances involving imaging with subpicosecond terahertz pulses have opened up a wide range of possibilities in the applications of farinfrared 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. (20030901)Inherent to photographlike 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 (20060401)Distributed wavelet processing within sensor networks holds promise for reducing communication energy and wireless bandwidth usage at sensor nodes. Local collaboration among nodes decorrelates measurements, yielding a ... 
Asymptotic Performance of Transmit Diversity via OFDM for Multipath Channels
Ahmed, Nadeem; Baraniuk, Richard G. (20021101)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 TreeStructured Image Modeling
Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (20000401)Waveletdomain 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 TreeStructured Image Modeling using Waveletdomain Hidden Markov Models
Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (20010701)Waveletdomain 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 TreeStructured Image Modeling using Waveletdomain Hidden Markov Models
Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (19990720)Waveletdomain 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. (19991001)Waveletdomain 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. (19940401)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. (19980901)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. (20020901)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. (20050801)We develop a quaternion wavelet transform (QWT) as a new multiscale analysis tool for geometric image features. The QWT is a near shiftinvariant, 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. (20061001)The quaternion wavelet transform (QWT) is a new multiscale analysis tool for geometric image features. The QWT is a near shiftinvariant 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 (20040601)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: RateDistortion Analysis
Chandrasekaran, Venkat; Wakin, Michael; Baron, Dror; Baraniuk, Richard G. (20040301)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 (20011001)Given a color image that was previously JPEGcompressed 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. (20040301)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 ... 
Connectionlevel Analysis and Modeling of Network Traffic
Sarvotham, Shriram; Riedi, Rudolf H.; Baraniuk, Richard G. (20011101)Most network traffic analysis and modeling studies lump all connections together into a single flow. Such aggregate traffic typically exhibits longrangedependent (LRD) correlations and nonGaussian marginal distributions. ... 
The Connexions Project: Promoting Open Sharing of Knowledge for Education
Henry, Geneva; Baraniuk, Richard G.; Kelty, Christopher (20030701)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. (20020501)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 opencontent and opensource licenses, Connexions offers ... 
Contextual Hidden Markov Models for Waveletdomain Signal Processing
Crouse, Matthew; Baraniuk, Richard G. (19971101)Waveletdomain 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 LowPass Filtering
Khojastepour, Mohammad; Aazhang, Behnaam; Baraniuk, Richard G. (20040501)We introduce a generalized definition for "lowpass" filters that covers timevarying 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. (20060501)We study the problem of designing support vector classifiers with respect to a NeymanPearson criterion. Specifically, given a userspecified 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. (19960301)We propose a straightforward characterization of all quadratic timefrequency representations covariant to an important class of unitary signal transforms (namely, those having two continuousvalued parameters and an ... 
DelayLimited Throughput Maximization for Fading Channels using Rate and Power Control
Ahmed, Nadeem; Khojestapour, Mohammad; Baraniuk, Richard G. (20041201)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 Multiscale Communication in Sensor Networks
PalChaudhuri, Santashil; Kumar, Rajnish; Baraniuk, Richard G.; Johnson, David B. (20050601)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. (20061101)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. (20040501)We extend the wavelet transform to handle multidimensional signals that are smooth save for singularities along lowerdimensional 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. (19991101)A combined spaceFourier representation focused on directional scale analysis is presented. The method leads to a spacelog polar frequency distribution. Application to seismic data shows differentiation in scale and ... 
Distributed Camera Network Localization
Mantzel, William; Choi, Hyeokho; Baraniuk, Richard G. (20041101)Localization, estimating the positions and orientations of a set of cameras, is a critical first step in camerabased 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. (20051101)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 SuperResolution
Wagner, Raymond; Nowak, Robert David; Baraniuk, Richard G. (20030901)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. (20050201)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 (20050701)Waveletbased 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. (20030901)Rice University has a decadeslong 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 DualTree Complex Wavelet Transform
Selesnick, Ivan W.; Baraniuk, Richard G.; Kingsbury, Nicholas G. (20051101)The paper discusses the theory behind the dualtree 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. (20000701)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. (19910401)An efficient method, based on the chirpz 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. (20030901)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
MagrinChagnolleau, Ivan; Baraniuk, Richard G. (19991101)This paper describes a new technique, called <i>Empirical Mode Decomposition</i> (EMD), which allows the decomposition of onedimensional signals into intrinsic oscillatory modes. Each component, called <i>Intrinsic Mode ... 
EstimationQuantization Geometry Coding Using Normal Meshes
Lavu, Sridhar; Choi, Hyeokho; Baraniuk, Richard G. (20030301)We propose a new algorithm for compressing threedimensional triangular mesh data used for representing surfaces. We apply the EstimationQuantization (EQ) algorithm originally designed for still image compression to the ... 
Fast, Exact Synthesis of Gaussian and nonGaussian LongRangeDependent Processes
Crouse, Matthew; Baraniuk, Richard G. (19990115)1/<i>f</i> noise and statistically selfsimilar processes such as fractional Brownian motion (fBm) are vital for modeling numerous realworld phenomena, from network traffic to DNA to the stock market. Although several ... 
Faster Sequential Universal Coding via Block Partitioning
Baron, Dror; Baraniuk, Richard G. (20060401)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. (19980901)We introduce and discuss biorthogonal wavelet transforms using the lifting construction. The lifting construction exploits a spatialdomain, predictionerror interpretation of the wavelet transform and provides a powerful ... 
ForWaRD: FourierWavelet Regularized Deconvolution for IllConditioned Systems
Neelamani, Ramesh; Choi, Hyeokho; Baraniuk, Richard G. (20040201)We propose an efficient, hybrid <i>FourierWavelet 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 TimeDomain Spectroscopy
Mittleman, Daniel M.; Jacobsen, R. H.; Neelamani, Ramesh; Baraniuk, Richard G.; Nuss, Martin C. (19980115)A method for detection and identification of polar gases and gas mixtures based on the technique of terahertz timedomain spectroscopy is presented. This relatively new technology promises to be the first portable farinfared ... 
A Geometric Hidden Markov Tree Wavelet Model
Romberg, Justin; Wakin, Michael; Choi, Hyeokho; Baraniuk, Richard G. (20030801)In the last few years, it has become apparent that traditional waveletbased image processing algorithms and models have significant shortcomings in their treatment of edge contours. The standard modeling paradigm exploits ...