Snake model is a kind of deformable image segmentation model based on parameters and has been proved effective to contour detecting as well. It is sensitive to the position of the initial curve

lacks the theoretical guidance to choose parameters and can not deal with the change of topological structure. Snake model is easy to leak out if the edge is weak. This paper presents a modified image force by integrating the region information to improve it. After that

Particle Swarm Optimization (PSO) algorithm is applied to optimize the segmentation results obtained by Snake model. The encouraging results have been shown by experiments with the synthesis images and medical images.