A novel method for image segmentation is proposed. Considering the segmentation results obtained by using the multiphase Chan-Vese model are dependent on initial conditions, an edge link method is used to obtain initial curve firstly. Based on the Four Color Theorem, we can assume that in general, at most two level set functions are sufficient to detect and represent distinct intensities. Then we use an improved four phase Chan-Vese model to segment the image. Experimental results of multi-objects image demonstrate the efficiency and accuracy of the algorithm in its segmentation operations.