Using delaunay trianglulation, thinning of a mass object.

Thinning algorithm based on morphology operation is not adopted for a mass object on image. It needs too many operations. To down-size a processing time one of the other methods is based on delaunay triangulation.

For a triangle having a edge in outside of a mass object, it is out of consideration.

Blue-colored triangles are out of consideration. And then it needs analysis the relationship of connectivity between triangles. A few definitions are enlisted. the End Triangle is defined as two edges of triangle meet outside of mass object, the Edge Triangle is defined as one edge of triangle meets outside of mass object, and the Branch Triangle is defined as none edge of triangle meets outside of mass object.

Blue-colored triangle indicates a End Triangle, Green-colored triangle indicates a Edge Triangle, and red-colored triangle indicates a Branch Triangle. According to connectivity among three types of triangles, the center of innercircle of End and Branch Triangle forms thinning lines.