Incremental component tree contour computation

A component tree is a graph representation that encodes the connected components of the upper or lower level sets of a grayscale image. Consequently, the nodes of a component tree represent binary images of the encoded connected components. There exist various algorithms that efficiently extract information and attributes of nodes of a component tree by incrementally exploiting the subset relation encoding in the tree. However, to the best of our knowledge, there is no such incremental approach to extract the contours of the nodes. In this paper, we propose an efficient incremental method to compute the contours of the nodes of a component tree by counting the edges (sides) of contour pixels. In addition, we discuss our method’s time complexity. We also experimentally show that our proposed method is faster than the standard approach based on node reconstruction.