Adaptive LMS L-filters for noise suppression in images

  • Authors:
  • C. Kotropoulos;I. Pitas

  • Affiliations:
  • Dept. of Inf., Aristotelian Univ. of Thessaloniki;-

  • Venue:
  • IEEE Transactions on Image Processing
  • Year:
  • 1996

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Abstract

Several adaptive least mean squares (LMS) L-filters, both constrained and unconstrained ones, are developed for noise suppression in images and compared in this paper. First, the location-invariant LMS L-filter for a nonconstant signal corrupted by zero-mean additive white noise is derived. It is demonstrated that the location-invariant LMS L-filter can be described in terms of the generalized linearly constrained adaptive processing structure proposed by Griffiths and Jim (1982). Subsequently, the normalized and the signed error LMS L-filters are studied. A modified LMS L-filter with nonhomogeneous step-sizes is also proposed in order to accelerate the rate of convergence of the adaptive L-filter. Finally, a signal-dependent adaptive filter structure is developed to allow a separate treatment of the pixels that are close to the edges from the pixels that belong to homogeneous image regions