1. An image segmentation method comprising: selecting a region of interest including an object whose image is to be segmented; detecting the edge of the object; repeatedly performing, until a specified precision is obtained, a process in which by using a layered mesh structure based on the detected edge, a mesh boundary of the object is detected, a mesh size is reduced by one layer, and by using areas adjacent to the detected mesh boundary, correcting the mesh boundary; and generating a mask to fill an inside area of the correcting mesh boundary and masking the object.