Level set method could efficiently solve the problem of the topologic change involved in the evolvement of the curve.Using the loop solution presented by level set method

active contour model based on global traits can segment objects efficiently.The paper uses this method to research segmentation technique in Chest Radiography Image.Taking account of the characteristic of Chest Radiography Image

a method with only once evolvement is presented here.We could get coarse lung area from original image and could get rib edge from local standard deviation image of Chest Radiography.The results verify that it is a robust way for Chest Radiography Image segmentation.