Table 3 Squared nearest neighbor deviation measured pixel by pixel. Comparison of variability in background estimates when a quantile and a morphological filter are used. The morphological filter γBδbis comparable to Spot's morph.close.open. The same parameter settings as in Table 1 have been used. The difference in s.n.n.d. between the quantile filter and the morphological filter is due to the block structure in the morphological filtered image.