// This script demonstrates how to median filter 
// an image using ImageJ's RankFilters class.

  importClass(Packages.ij.plugin.filter.RankFilters)
  img = IJ.getImage();
  ip = img.getProcessor();
  filter = new RankFilters();
  radius = 3;
  filter.rank(ip, radius, RankFilters.MEDIAN);
  img.updateAndDraw();
  IJ.showProgress(1);