Analysis of the Watershed Algorithms Based on the Breadth-First and Depth-First Exploring Methods

In this paper, fifteen watershed algorithms are reviewed. For clarity, first we expose two graph exploring methods modified to be guidelines for understanding the approaches taken by these algorithms: the breadth-first watershed and the depth-first watershed. Both paradigms rely on the visiting order applied by the algorithms. The breadth-first is more recognizable as a seed region growing or marker expansion process, grouping both methods based on flooding and hierarchical queue. The depth-first groups the algorithms based on the drop of water simulation, forming a simple path until a regional minimum is found. We analyze and classify fifteen algorithms, and two of them were better characterized. Along with this, some useful information (i.e. use of markers and line over pixel) is organized, in order to facilitate the choice of an algorithm.