1. A method for generating superpixels for an image having pixels, the method comprising: clustering the pixels into initial clusters; determining one spatially coherent part of each of the clusters, all other parts of each cluster being considered as unconnected fragments and being set to unassigned and marked as mutable; and assigning pixels of the unconnected fragments to adjacent clusters using a contour evolution process based on the spatially coherent parts of the clusters as initial adjacent clusters that processes only the pixels that are in a region marked as mutable.