Efficient 3x3 Median Filter Computations

Information

• Publication Type: Technical Report
• Workgroup(s)/Project(s): not specified
• Date: December 1994
• Number: TR-186-2-94-18
• Keywords: image processing, filtering, 3x3 median kernel, spatial coherence

Abstract

This Paper presents an efficient algorithm for median filtering with a 3x3 filter kernel with only about 9 comparisons per pixel using spatial coherence between neighbouring filter computations. The basic algorithm calculates two medians in one step and reuses sorted slices of three vertical neighbouring pixels. An extension of this algorithm for 2D spatial coherence is also examined, which calculates four medians per step. Even though theoretical results would yield 5% performance increase compared to the basic algorithm, experimental results showed less significant increase or even worse performance dependent on the hardware.

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BibTeX

@techreport{Kopp-1994-EMF,
  title =      "Efficient 3x3 Median Filter Computations",
  author =     "Manfred Kopp and Werner Purgathofer",
  year =       "1994",
  abstract =   "This Paper presents an efficient algorithm for median
               filtering with a 3x3 filter kernel with only about 9
               comparisons per pixel using spatial coherence between
               neighbouring filter computations. The basic algorithm
               calculates two medians in one step and reuses sorted slices
               of three vertical neighbouring pixels. An extension of this
               algorithm for 2D spatial coherence is also examined, which
               calculates four medians per step. Even though theoretical
               results would yield 5% performance increase compared to the
               basic algorithm, experimental results showed less
               significant increase or                 even worse
               performance dependent on the hardware.",
  month =      dec,
  number =     "TR-186-2-94-18",
  address =    "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria",
  institution = "Institute of Computer Graphics and Algorithms, Vienna
               University of Technology ",
  note =       "human contact: technical-report@cg.tuwien.ac.at",
  keywords =   "image processing, filtering, 3x3 median kernel, spatial
               coherence",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/1994/Kopp-1994-EMF/",
}