1. A method for corpus callosum segmentation in an MR image, comprising: generating an initial corpus callosum contour in said MR image; determining a boundary of the corpus callosum in said MR image by fitting said corpus callosum contour to said MR image using an active shape model with confidence weighting; and refining said boundary of the corpus callosum based on intensity distributions in object and background regions defined by said boundary of the corpus callosum.