Watershed segmentation of binary images using distance transformations
Curt L. Orbert, Ewert W. Bengtsson, Bo G. Nordin · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1993
A common problem with binary images generated by a segmentation algorithm is to split the domains either into different objects or an object into different parts. While it is easy to do this interactively by drawing lines in the image it is a much more difficult task to formulate rules for this operation in a computer language and thus automate the procedure. This paper presents a fast algorithm that yields results very similar to an interactive splitting procedure for the domains of a binary image. The algorithm is based on watershed segmentation using distance transformations. We let a pixel belong to a watershed line if at least two neighbors belong to differently labeled segments. We have criteria for relabeling segments which do not become large enough to form segments of their own. After having labeled all pixels we replace every watershed line with the lines with shortest distances. The algorithm preserves the shape and the number of segments with good accuracy and is also independent of how the domains are rotated in the image.