Now showing items 1-20 of 270

    • 3-D Local Radon Power Spectra for Seismic Attribute Extraction 

      Steeghs, Philippe; Fokkema, Jacob T; Diephuis, Gerhard (1998-01-15)
      In this paper we discuss a method for volume attribute extraction that is based on a new type of local Radon power spectrum. The new algorithm results in robust and geologically meaningful volume attributes, such as volume dip and azimuth. Seismic volume attribute analysis greatly facilitates the interpretation of large 3-D seismic data volumes. ...
    • Adaptive Iterative Reqeighted Least Squares Design of LP FIR Filters 

      Vargas, Ricardo; Burrus, C. Sidney (1999-03-01)
      This paper presents an efficient adaptive algorithm for designing FIR digital filters that are efficient according to an Lp error criteria. The algorithm is an extension of Burrus' iterative reweighted least-squares (IRLS) method for approximating Lp filters. Such algorithm will converge for most significant cases in a few iterations. In some cases ...
    • Adaptive Representation of JPEG 2000 Images Using Header-based Processing 

      Neelamani, Ramesh; Berkner, Kathrin (2002-09-20)
      To bridge the mismatch between the sizes of images and display devices, we present an efficient and automatic algorithm to create an adaptive image representation called SmartNail. Given a digital image and rectangular display frame smaller than the image, we define the SmartNail as an appropriately cropped part of a suitably scaled-down image. We ...
    • 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, we examine the central issues of invertibility, stability, and artifacts in its construction. We describe a new type of ...
    • 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, we examine the central issues of invertibility, stability, and artifacts in its construction. We describe a new type of ...
    • 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 decay slowly and are expensive to code. We focus on improving the transform by incorporating adaptivity. Construction of nonlinear ...
    • 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 framework for designing customized transforms. We use the lifting construction to adaptively tune a wavelet transform to a desired ...
    • Adding Linguistic Constraints to Document Image Decoding: Comparing the Iterated Complete Path and Stack Algorithms 

      Popat, Kris; Greene, Dan; Romberg, Justin; Bloomberg, Dan (2001-01-20)
      Beginning with an observed document image and a model of how the image has been degraded, Document Image Decoding recognizes printed text by attempting to find a most probable path through a hypothesized Markov source. The incorporation of linguistic constraints, which are expressed by a sequential predictive probabilistic language model, can improve ...
    • 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. This behavior can be explained by forming two components of the traffic according to the speed of connections, one component ...
    • Allpass Filter Design and Applications 

      Lang, Markus (1995-01-15)
      The Problem of allpass filter design for phase approximation and equalization in the Chebyshev sense is solved by using a generalized Remez algorithm. Convergence to the unique optimum is guaranteed and is achieved rapidly in the actual implementation. The well-known numerical problems for higher degree filters are analyzed and solved by a simple ...
    • 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 the technique to wavelet domain Hidden Markov Tree (HMT) models used in image segmentation. The technique is easily applied, because ...
    • Analysis of noise reduction in redundant expansions under distributed processing requirements 

      Rozell, Chris; Johnson, Don (2005-03-01)
      We considered signal reconstruction with redundant expansions under distributed processing in noisy environments. Redundant expansions have the ability to reduce noise corrupting the coefficients, but distributed processing schemes will not be able to take full advantage of the redundancy present. We apply frame theory and a generalization called â ...
    • 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, it has not been clear how to choose the signal model used to design the filter, because the effect of model selection on the ...
    • Analyzing the robustness of redundant population codes in sensory and feature extraction systems 

      Rozell, Chris; Johnson, Don (2005-07-01)
      Sensorineural systems often use groups of redundant neurons to represent stimulus information both during transduction and population coding of features. This redundancy makes the system more robust to corruption in the representation. We approximate neural coding as a projection of the stimulus onto a set of vectors, with the result encoded by spike ...
    • 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. Examples are given which demonstrate the effectiveness of the approach for simulated and real sonar data. The simulations indicate ...
    • 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 imaging spectrometer seems a realizable prospect. However, several substantial engineering research challenges remain to be overcome ...
    • Approximate continuous wavelet transform with an application to noise reduction 

      Lewis, James M.; Burrus, C. Sidney (1998-05-20)
      We describe a generalized scale-redundant wavelet transform which approximates a dense sampling of the continuous wavelet transform (CWT) in both time and scale. The dyadic scaling requirement of the usual wavelet transform is relaxed in favor of an approximate scaling relationship which in the case of a Gaussian scaling function is known to be ...
    • 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 developed that take advantage of each of these types of structure independently: quadtree models for 2D wavelets are well-suited ...
    • 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 sparser data set with significant values at far fewer nodes. Sparsity can then be leveraged for subsequent processing such as ...
    • ASIP Architecture for Future Wireless Systems: Flexibility and Customization 

      Cavallaro, Joseph R.; Radosavljevic, Predrag (2004-06-01)
      Efficiency and flexibility are crucial features of the processors in the next generation of wireless cellular systems. Processors need to be efficient in order to satisfy real-time requirements for very demanding algorithms in new emerging wireless standards (3GPP, 4G, 802.11x, WiFi, DVD-S2, DAB, just to name a few). Flexibility, on the other hand, ...