A Shock-Capturing Algorithm for the Differential Equations of Dilation and Erosion

  • Authors:
  • Michael Breuß;Joachim Weickert

  • Affiliations:
  • Faculty of Mathematics and Computer Science, Saarland University, Saarbrücken, Germany 66041;Faculty of Mathematics and Computer Science, Saarland University, Saarbrücken, Germany 66041

  • Venue:
  • Journal of Mathematical Imaging and Vision
  • Year:
  • 2006

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Abstract

Dilation and erosion are the fundamental operations in morphological image processing. Algorithms that exploit the formulation of these processes in terms of partial differential equations offer advantages for non-digitally scalable structuring elements and allow sub-pixel accuracy. However, the widely-used schemes from the literature suffer from significant blurring at discontinuities. We address this problem by developing a novel, flux corrected transport (FCT) type algorithm for morphological dilation/erosion with a flat disc. It uses the viscosity form of an upwind scheme in order to quantify the undesired diffusive effects. In a subsequent corrector step we compensate for these artifacts by means of a stabilised inverse diffusion process that requires a specific nonlinear multidimensional formulation. We prove a discrete maximum---minimum principle in this multidimensional framework. Our experiments show that the method gives a very sharp resolution of moving fronts, and it approximates rotation invariance very well.