Non-uniform Resolution Recovery Using Median Priors in Tomographic Image Reconstruction Methods

  • Munir Ahmad
  • Andrew Todd-Pokropek
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4673)


Penalized-Likelihood (PL) image reconstruction methods produce better quality images than analytical methods. However, these methods produce images with non-uniform resolution properties. A number of prior functions have been used to recover for this reconstructed resolution non-uniformity. Quadratic Priors (QPs) are preferred due to their simplicity and their resolution characteristics have been studied extensively. Images reconstructed using QPs still exhibit non-uniform resolution properties.Here, we propose median priors (MPs) in place of QPs and evaluate their resolution characteristics.Although, they produce images with non-uniform reconstructed resolution, their recovered resolution is better than the QPs.We have also implemented MPs in a modified penalty frame work, proposed for QPs, and have shown that they produce images with almost uniform resolution. Due to their automatic edge preservation and better quantitative properties, MPs might be preferred over QPs for penalize-likelihood image reconstruction.


Penalized-Likelihood Quadratic Priors Median Priors Resolution Edge preservation 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2007

Authors and Affiliations

  • Munir Ahmad
    • 1
  • Andrew Todd-Pokropek
    • 1
  1. 1.Medical Physics and Bioengineering, University College LondonUK

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