An Introduction to Morphological Filters in Surface Metrology

Acting as the complementary tool to the mean-line based filtration techniques, e.g. the Gaussian filter, morphological filters are function oriented and relevant to geometrical features of surfaces. This paper aims to present an introduction to morphological filters in surface metrology. By introducing mathematical morphology, morphological filters offer more capabilities than the early envelope system. The variation of morphological filters includes: the closing filter, the opening filter, the alternating symmetrical filter and multi-scale space techniques. The existing algorithms concerning with the implementation of morphological filters are presented. A couple of typical applications of morphological filters are illustrated as well.