Now showing items 1-11 of 11

  • 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 ...
  • Enhancement of Decompressed Images at Low Bit Rates 

    Gopinath, Ramesh A.; Lang, Markus; Guo, Haitao; Odegard, Jan E. (1994-07-20)
    Transform coding at low bit rates introduces artifacts associated with the basis functions of the transform. For example, decompressed images based on the DCT (discrete cosine transform)- like JPEG<sup>16</sup> - exhibit ...
  • 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 ...
  • Image Compression using an Efficient Edge Cartoon + Texture Model 

    Wakin, Michael; Romberg, Justin; Choi, Hyeokho; Baraniuk, Richard G. (IEEE Computer Society, 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 ...
  • Image Compression using Multiscale Geometric Edge Models 

    Wakin, Michael (2002-05-20)
    Edges are of particular interest for image compression, as they communicate important information, contribute large amounts of high-frequency energy, and can generally be described with few parameters. Many of today's most ...
  • Joint Compression and Speckle Reduction of SAR Images using Embedded Zerotree Models 

    Odegard, Jan E.; Guo, Haitao; Burrus, C. Sidney; Baraniuk, Richard G. (1996-03-01)
    We propose a new method for speckle reduction in synthetic aperture radar (SAR) imagery based on the embedded zerotree image compression algorithm. This new approach to denoising is inspired by the realization that the ...
  • On The Problem of Simultaneous Encoding of Magnitude and Location Information 

    Castro, Rui; Wakin, Michael; Orchard, Michael (2002-11-20)
    Modern image coders balance bitrate used for encoding the location of signicant transform coefficients, and bitrate used for coding their values. The importance of balancing location and value information in practical ...
  • Phase and Magnitude Perceptual Sensitivities in Nonredundant Complex Wavelet Representations 

    Wakin, Michael; Orchard, Michael; Baraniuk, Richard G.; Chandrasekaran, Venkat (2003-11-01)
    The recent development of a nonredundant complex wavelet transform allows a novel framework for image analysis. Work on this representation has recognized that the phase and magnitude of complex coefficients can be related ...
  • 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 ...
  • Representation and Compression of Multi-Dimensional Piecewise Functions Using Surflets 

    Chandrasekaran, Venkat; Wakin, Michael; Baron, Dror; Baraniuk, Richard G. (2006-03-01)
    We study the representation, approximation, and compression of functions in M dimensions that consist of constant or smooth regions separated by smooth (M-1)-dimensional discontinuities. Examples include images containing ...
  • Surflets: A Sparse Representation for Multidimensional Functions Containing Smooth Discontinuities 

    Chandrasekaran, Venkat; Wakin, Michael; Baron, Dror; Baraniuk, Richard G. (2004-07-01)
    Discontinuities in data often provide vital information, and representing these discontinuities sparsely is an important goal for approximation and compression algorithms. Little work has been done on efficient representations ...