Processing the image gradient field using a topographic primal sketch approach

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The spatial derivatives of the image intensity provide topographic information that may be used to identify and segment objects. The accurate computation of the derivatives is often hampered in medical images by the presence of noise and a limited resolution. This paper focuses on accurate computation of spatial derivatives and their subsequent use to process an image gradient field directly, from which an image with improved characteristics can be reconstructed. The improvements include noise reduction, contrast enhancement, thinning object contours and the preservation of edges.

Processing the gradient field directly instead of the image is shown to have numerous benefits. The approach is developed such that the steps are modular, allowing the overall method to be improved and possibly tailored to different applications. As presented, the approach relies on a topographic representation and primal sketch of an image.

Comparisons with existing image processing methods on a synthetic image and different medical images show improved results and accuracy in segmentation. Here the focus is on objects with low spatial resolution, which is often the case in medical images. The methods developed show the importance of improved accuracy in derivative calculation, and the potential in processing the image gradient field directly.
Original languageEnglish
Article numbere02706
Number of pages24
JournalInternational Journal for Numerical Methods in Biomedical Engineering
Issue number3
Early online date13 Feb 2015
Publication statusPublished - Mar 2015


  • finite difference
  • least squares
  • contrast enhancement
  • image filtering
  • segmentation
  • reconstruction from gradient field


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