Abstract: The “active contours without edges” model proposed by Chan and Vese（C-V model） is one of the well-known region-
based image segmentation models.The C-V model employs the well-known Mumford-Shah functional to deal with the problem of image segmentation by using piecewise constant representation.In this model，the weight parameter of the area term in the energy functional is chosen to be a nonnegative constant；however，this restriction may limit the applicability of the model in some applications.The empirical research shows that the C-V model with negative area parameter can segment some images that the original C-V model is not applicable to.