Now showing items 1-20 of 46

    • 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 (1998)
      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 (1999-01-15)
      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 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 ...
    • A Bayesian Multiscale Approach to Joint Image Restoration and Edge Detection 

      Wan, Yi; Nowak, Robert David (1999-07-20)
      This paper presents a novel wavelet-based method for simultaneous image restoration and edge detection. The Bayesian framework developed here is general enough to treat a wide class of linear inverse problems involving ...
    • Coding Theoretic Approach to Image Segmentation 

      Ndili, Unoma; Nowak, Robert David; Figueiredo, Mario (2001-10-20)
      In this paper, using a coding theoretic approach, we implement Rissanen's concept of minimum description length (MDL) for segmenting an image into piecewise homogeneous regions. Our image model is a Gaussian random field ...
    • CORT: Classification Or Regression Trees 

      Scott, Clayton; Willett, Rebecca; Nowak, Robert David (2003-06-20)
      In this paper we challenge three of the underlying principles of CART, a well know approach to the construction of classification and regression trees. Our primary concern is with the penalization strategy employed to prune ...
    • CORT: Classification Or Regression Trees 

      Scott, Clayton; Willett, Rebecca; Nowak, Robert David (2003-04-20)
      In this paper we challenge three of the underlying principles of CART, a well know approach to the construction of classification and regression trees. Our primary concern is with the penalization strategy employed to prune ...
    • 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 ...
    • Efficient Methods for Identification of Volterra Filters 

      Nowak, Robert David; Van Veen, Barry D. (1994)
      A major drawback of the truncated Volterra series or "Volterra filter" for system identification is the large number of parameters required by the standard filter structure. The corresponding estimation problem requires ...
    • Generalized likelihood ratio detection for fMRI using complex data 

      Nan, F.Y.; Nowak, Robert David (1999-04-20)
      The majority of fMRI studies obtain functional information using statistical tests based on the magnitude image reconstructions. Recently, a complex correlation (CC) test was proposed based on teh complex image data in ...
    • Hidden Markov Models for Wavelet-based Signal Processing 

      Crouse, Matthew; Baraniuk, Richard G.; Nowak, Robert David (1996-11-01)
      Current wavelet-based statistical signal and image processing techniques such as shrinkage and filtering treat the wavelet coefficients as though they were statistically independent. This assumption is unrealistic; considering ...
    • Hierarchical Wavelet-Based Image Model for Pattern Analysis and Synthesis 

      Scott, Clayton; Nowak, Robert David (2000-07-20)
      Despite their success in other areas of statistical signal processing, current wavelet-based image models are inadequate for modeling patterns in images, due to the presence of unknown transformations (e.g., translation, ...
    • Image Restoration Using the EM Algorithm and Wavelet-Based Complexity Regularization 

      Figueiredo, Mario; Nowak, Robert David (2002-05-20)
      This paper introduces an <i>expectation-maximization</i> (EM) algorithm for image restoration (deconvolution) based on a penalized likelihood formulated in the wavelet domain. Regularization is achieved by promoting a ...
    • Lifting Construction of Non-Linear Wavelet Transforms 

      Claypoole, Roger L.; Baraniuk, Richard G.; Nowak, Robert David (1998-10-01)
      This paper analyzes non-linear wavelet transforms using the lifting construction. The lifting construction exploits a spatial-domain, prediction-error interpretation of the wavelet transform and provides a powerful framework ...
    • Low Rank Estimation of Higher Order Statistics 

      Nowak, Robert David; Van Veen, Barry D. (1995-12-01)
      Low rank estimators for higher order statistics are considered in this paper. Rank reduction methods offer a general principle for trading estimator bias for reduced estimator variance. The bias-variance tradeoff is analyzed ...
    • Model-based Inverse Halftoning with Wavelet-Vaguelette Deconvolution 

      Neelamani, Ramesh; Nowak, Robert David; Baraniuk, Richard G. (2000-09-01)
      In this paper, we demonstrate based on the linear model of Kite that inverse halftoning is equivalent to the well-studied problem of deconvolution in the presence of colored noise. We propose the use of the simple and ...
    • Multiresolution Nonparametric Intensity and Density Estimation 

      Willett, Rebecca; Nowak, Robert David (2002-05-20)
      This paper introduces a new multiscale method for nonparametric piecewise polynomial intensity and density estimation of point processes. Fast, piecewise polynomial, maximum penalized likelihood methods for intensity and ...
    • A Multiscale Bayesian Framework for Linear Inverse Problems and Its Application to Image Restoration 

      Wan, Yi; Nowak, Robert David (2001-01-20)
      In this paper we develop a wavelet-based statistical method for solving linear inverse problems. The Bayesian framework developed here is general enough to treat a wide class of linear inverse problems involving (white ...
    • Multiscale Density Estimation 

      Willett, Rebecca; Nowak, Robert David (2003-08-20)
      The nonparametric density estimation method proposed in this paper is computationally fast, capable of detecting density discontinuities and singularities at a very high resolution, spatially adaptive, and offers near ...