Now showing items 1-52 of 52

  • 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: ...
  • Wavelet-Domain Approximation and Compression of Piecewise Smooth Images 

    Wakin, Michael; Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2006-05-01)
    The wavelet transform provides a sparse representation for smooth images, enabling efficient approximation and compression using techniques such as zerotrees. Unfortunately, this sparsity does not extend to piecewise smooth ...
  • The Multiscale Structure of Non-Differentiable Image Manifolds 

    Wakin, Michael; Donoho, David; Choi, Hyeokho; Baraniuk, Richard G. (2005-08-01)
    In this paper, we study families of images generated by varying a parameter that controls the appearance of the object/scene in each image. Each image is viewed as a point in high-dimensional space; the family of images ...
  • 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 ...
  • 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 ...
  • An FPGA-based Daughtercard for TIs C6000 family of DSKs 

    Gadhiok, Manik; Hardy, Ricky; Murphy, Patrick; Frantz, Patrick; Choi, Hyeokho; Cavallaro, Joseph R. (2005-06-01)
    In this paper we present an FPGA-based daughtercard designed for TIs C6000 family of DSP Starter Kits (DSKs). The hardware, initially designed for a course project, provides a platform for studying heterogeneous systems ...
  • High-Resolution Navigation on Non-Differentiable Image Manifolds 

    Wakin, Michael; Donoho, David; Choi, Hyeokho; Baraniuk, Richard G. (2005-03-01)
    The images generated by varying the underlying articulation parameters of an object (pose, attitude, light source position, and so on) can be viewed as points on a low-dimensional <i>image parameter articulation manifold</i> ...
  • Multiscale Manifold Representation and Modeling 

    Choi, Hyeokho; Baraniuk, Richard G. (2005-03-01)
    Many real world data sets can be viewed as points in a higher-dimensional space that lie concentrated around a lower-dimensional manifold structure. We propose a new multiscale representation for such point clouds based ...
  • 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, ...
  • Wavelet-domain Approximation and Compression of Piecewise Smooth Images 

    Wakin, Michael; Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2005-01-15)
    The wavelet transform provides a sparse representation for smooth images, enabling efficient approximation and compression using techniques such as zerotrees. Unfortunately, this sparsity does not extend to <i>piecewise ...
  • 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 ...
  • Multilingual Open-Content Signal Processing Laboratories in Connexions 

    Frantz, Patrick; Baraniuk, Richard G.; Choi, Hyeokho; Jones, Douglas L. (2004-11-01)
    Due to inherent factors like a small and fragmented market and rapid hardware obsolescence, the conventional textbook is inadequate for DSP laboratory education. Freely available open-content materials that enable and ...
  • 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 ...
  • Multiple wavelet basis image denoising using Besov ball projections 

    Choi, Hyeokho; Baraniuk, Richard G. (2004-09-01)
    We propose a new image denoising algorithm that exploits an image's representation in multiple wavelet domains. Besov balls are convex sets of images whose Besov norms are bounded from above by their radii. Projecting an ...
  • 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 ...
  • 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 ...
  • 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 ...
  • 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 ...
  • Geometric Methods for Wavelet-Based Image Compression 

    Wakin, Michael; Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2003-08-01)
    Natural images can be viewed as combinations of smooth regions, textures, and geometry. Wavelet-based image coders, such as the space-frequency quantization (SFQ) algorithm, provide reasonably efficient representations for ...
  • 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 ...
  • Geometry Compression of Normal Meshes using Rate-Distortion Algorithms 

    Lavu, Sridhar; Choi, Hyeokho; Baraniuk, Richard G. (2003-06-01)
    We propose a new rate-distortion based algorithm for compressing 3D surface geometry represented using triangular normal meshes. We apply the Estimation-Quantization (EQ) algorithm to compress normal mesh wavelet coefficients. ...
  • 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 ...
  • Wavelet Statistical Models and Besov Spaces 

    Choi, Hyeokho; Baraniuk, Richard G. (2003-01-15)
    No Abstract
  • Geometric Tools for Image Compression 

    Wakin, Michael; Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2002-11-01)
    Images typically contain strong geometric features, such as edges, that impose a structure on pixel values and wavelet coefficients. Modeling the joint coherent behavior of wavelet coefficients is difficult, and standard ...
  • 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 ...
  • Hidden Markov Tree Models for Complex Wavelet Transforms 

    Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G.; Kingsbury, Nicholas G. (2002-05-01)
    Multiresolution models such as the hidden Markov tree (HMT) aim to capture the statistical structure of signals and images by leveraging two key wavelet transform properties: wavelet coefficients representing smooth/singular ...
  • Image Compression using an Efficient Edge Cartoon + Texture Model 

    Wakin, Michael; Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2002-04-01)
    Wavelet-based image coders optimally represent smooth regions and isolated point singularities. However, wavelet coders are less adept at representing perceptually important edge singularities, and coding performance ...
  • Multiscale Image Processing Using Normal Triangulated Meshes 

    Jansen, Maarten; Choi, Hyeokho; Lavu, Sridhar; Baraniuk, Richard G. (2001-10-01)
    Multiresolution triangulation meshes are widely used in computer graphics for 3-d modelling of shapes. We propose an image representation and processing framework using a multiscale triangulation of the grayscale function. ...
  • Multiscale Edge Grammars for Complex Wavelet Transforms 

    Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (2001-10-01)
    Wavelet domain algorithms have risen to the forefront of image processing. The power of these algorithms is derived from the fact that the wavelet transform restructures the image in a way that makes statistical modeling ...
  • Multiscale Image Segmentation using Wavelet-domain Hidden Markov Models 

    Choi, Hyeokho; Baraniuk, Richard G. (2001-09-01)
    We introduce a new image texture segmentation algorithm, HMTseg, based on wavelets and the hidden Markov tree (HMT) model. The HMT is a tree-structured probabilistic graph that captures the statistical properties of the ...
  • 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 ...
  • Multiscale Classification using Complex Wavelets and Hidden Markov Tree Models 

    Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G.; Kingsbury, Nicholas G. (2000-09-01)
    Multiresolution signal and image models such as the hidden Markov tree (HMT) aim to capture the statistical structure of smooth and singular (textured and edgy) regions. Unfortunately, models based on the orthogonalwavelet ...
  • Multiscale Image Segmentation Using Joint Texture and Shape Analysis 

    Neelamani, Ramesh; Romberg, Justin; Riedi, Rudolf H.; Choi, Hyeokho; Baraniuk, Richard G. (2000-07-01)
    We develop a general framework to simultaneously exploit texture and shape characterization in multiscale image segmentation. By posing multiscale segmentation as a model selection problem, we invoke the powerful framework ...
  • Multiplicative Multiscale Image Decompositions: Analysis and Modeling 

    Romberg, Justin; Riedi, Rudolf H.; Choi, Hyeokho; Baraniuk, Richard G. (2000-07-01)
    Multiscale processing, in particular using the wavelet transform, has emerged as an incredibly effective paradigm for signal processing and analysis. In this paper, we discuss a close relative of the Haar wavelet transform, ...
  • 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. ...
  • Hidden Markov Tree Modeling of Complex Wavelet Transforms 

    Choi, Hyeokho; Romberg, Justin; Baraniuk, Richard G.; Kingsbury, Nicholas G. (2000-06-01)
    Multiresolution signal and image models such as the hidden Markov tree aim to capture the statistical structure of smooth and singular (edgy) regions. Unfortunately, models based on the orthogonal wavelet transform suffer ...
  • 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 ...
  • Multiscale SAR Image Segmentation using Wavelet-domain Hidden Markov Tree Models 

    Venkatachalam, Vidya; Choi, Hyeokho; Baraniuk, Richard G. (2000-04-01)
    We study the segmentation of SAR imagery using wavelet-domain Hidden Markov Tree (HMT) models. The HMT model is a tree-structured probabilistic graph that captures the statistical properties of the wavelet transforms of ...
  • Wavelet-based deconvolution for ill-conditioned systems 

    Neelamani, Ramesh; Choi, Hyeokho; Baraniuk, Richard G. (2000-02-01)
    We propose a hybrid approach to wavelet-based deconvolution that comprises Fourier-domain system inversion followed by wavelet-domain noise suppression. In contrast to other wavelet-based deconvolution approaches, the ...
  • Multiscale Texture Segmentation of Dip-cube Slices using Wavelet-domain Hidden Markov Trees 

    Magrin-Chagnolleau, Ivan; Choi, Hyeokho; van Spaendonck, Rutger; Steeghs, Philippe; Baraniuk, Richard G. (1999-11-01)
    Wavelet-domain Hidden Markov Models (HMMs) are powerful tools for modeling the statistical properties of wavelet coefficients. By characterizing the joint statistics of wavelet coefficients, HMMs efficiently capture the ...
  • Shift-Invariant Denoising using Wavelet-Domain Hidden Markov Trees 

    Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (1999-10-20)
    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 statistics of the wavelet coefficients ...
  • 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 ...
  • Shift-Invariant Denoising using Wavelet-Domain 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 statistical signal and image processing. The hidden Markov tree (HMT) model captures the key features of the joint statistics of the wavelet coefficients ...
  • Wavelet-Domain Regularized Deconvolution for Ill-Conditioned Systems 

    Neelamani, Ramesh; Choi, Hyeokho; Baraniuk, Richard G. (1999-10-01)
    We propose a hybrid approach to wavelet-based image deconvolution that comprises Fourier-domain system inversion followed by wavelet-domain noise suppression. In contrast to conventional wavelet-based deconvolution approaches, ...
  • Multiple Basis Wavelet Denoising using Besov Projections 

    Choi, Hyeokho; Baraniuk, Richard G. (1999-10-01)
    Wavelet-based image denoising algorithm depends upon the energy compaction property of wavelet transforms. However, for many real-world images, we cannot expect good energy compaction in a single wavelet domain, because ...
  • 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 ...
  • Wavelet-Based Deconvolution Using Optimally Regularized Inversion for Ill-Conditioned Systems 

    Neelamani, Ramesh; Choi, Hyeokho; Baraniuk, Richard G. (1999-07-20)
    We propose a hybrid approach to wavelet-based deconvolution that comprises Fourier-domain system inversion followed by wavelet-domain noise suppression. In contrast to conventional wavelet-based deconvolution approaches, ...
  • 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 ...
  • Wavelet-based Deconvolution for Ill-conditioned Systems 

    Neelamani, Ramesh; Choi, Hyeokho; Baraniuk, Richard G. (1999-03-01)
    In this paper, we propose a new approach to wavelet-based deconvolution. Roughly speaking, the algorithm comprises Fourier-domain system inversion followed by wavelet-domain noise suppression. Our approach subsumes a number ...
  • Interpolation and Denoising of Nonuniformly Sampled Data using Wavelet-domain Processing 

    Choi, Hyeokho; Baraniuk, Richard G. (1999-03-01)
    In this paper, we link concepts from nonuniform sampling, smoothness function spaces, interpolation, and denoising to derive a suite of multiscale, maximum-smoothness interpolation algorithms. We formulate the interpolation ...
  • Multiscale Texture Segmentation using Wavelet-domain Hidden Markov Models 

    Choi, Hyeokho; Baraniuk, Richard G. (1998-11-01)
    Wavelet-domain hidden Markov tree (HMT) models are powerful tools for modeling the statistical properties of wavelet transforms. By characterizing the joint statistics of the wavelet coefficients, HMTs efficiently capture ...
  • 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, ...