On the morphological processing of objects with varying local contrast

Abstract

Most morphological operators appear by pairs such as erosion/dilation, opening/closing, and thinning/thickening. These are pairs of dual operators with respect to set complementation. The output of a (dual) morphological operator applied to an object depends on whether it is a bright object over a dark background or a dark object over a bright background. When dealing with complex images such as earth observation data, there is no clear distinction between the background and the foreground because the image consists of a partition of the space into image objects of arbitrary intensity values. In this paper, we present an overview of existing approaches for tackling this problem and propose new techniques based on area filters applied first to the image extrema and then to all flat regions. © Springer-Verlag Berlin Heidelberg 2003.