On morphological operators based on rank filters

摘要

Rank order morphological operators have been designed to better cope with shape variations and noise than the corresponding operators with plain structuring elements. In this paper, starting from a brief historical overview of rank order filters and erosions/dilations in digital image processing, rank order based morphological operators are surveyed. We also highlight the relations between these operators and show that many are similar if not equivalent. An extensive bibliography is provided.