Replace each element by the median of its radius-r neighborhood (1D/2D lists and images)
MedianFilter[image, r]
MedianFilter[data, {r1, r2, …}]
MedianFilter[ {1, 2, 3, 2, 1}, 1]
→ {3/2, 2, 2, 2, 3/2}MedianFilter[{0, 3, 8, 2}, 1]
→ {3/2, 3, 3, 5}ListLinePlot[{data, MedianFilter[data, 3]}]
→ -Graphics-