Single linkage region growing algorithms based on the vector degree of match

The class of the single linkage region growing (SLRG) algorithms, in which pairs of neighboring pixels are compared for merging, is one of the conceptually simplest approaches to image segmentation. A new normalized coefficient, which measures the degree of match between two multivalued vectors, termed the vector degree of match (VDM), provides the SLRG applications with the metric needed to group adjacent pixel pairs. Two new SLRG algorithms, applied to multiband images and exploiting the VDM criterion, are presented. Their major advantage, in comparison with the SLRG implementations found in the literature, is that they required only one user-defined parameter, the VDM Threshold (VDMT), which is a normalized value featuring local adaptivity and having an intuitive physical meaning. The use of an SLRG module is convenient as the first stage of a structured segmentation procedure featuring the following functional properties: (i) it is implemented sequentially; (ii) it combines single linkage, centroid linkage and hybrid linkage criteria; and (iii) its goal is the detection of image areas characterized by low contrast