A Spatially Variant, Locally Adaptive, Background Normalization Operator

Abstract

This paper describes a spatially variant, locally adaptive, background normalization operator that is defined in terms of morphological openings and closings. The variable opening (and closing) residue operators address the problems that can occur when one attempts to choose a single structuring element size for background normalization purposes, in cases where the objects of interest have multiple or unknown widths. The operators attempt to assign a natural width to each pixel in an image, based on the opening or closing size that causes the largest change in its value. This size then also determines a local contrast value for that pixel. The size, local contrast and original grey values of pixels in an image can be used to cluster pixels as an aid to performing image segmentation, or foreground-background discrimination. This paper describes and illustrates the algorithm, and discusses how its outputs may be used for image analysis and parameter selection.