1. A method of rearranging a cluster map ( 400 ) of voxels in an image, the cluster map resulting from applying ( 301 ) a clustering algorithm on the image, where the cluster map includes at least two cluster levels ( 407 - 409 ), the clustering algorithm further being arranged to determine the distribution of the voxels ( 406 ) within the cluster map and to determine at least one boundary parameter ( 404 , 405 ) that separates the distribution into at least two distribution domains ( 401 - 403 ), wherein each respective distribution domain reflects the distribution of the voxels of a single cluster level ( 407 - 409 ), the method comprising: providing ( 305 ) an input value indicating at least one updated boundary parameter ( 404 , 405 ) where the boundary parameter indicates an updated population of the distribution domains ( 401 - 403 ), and re-calculating ( 307 ) the cluster levels in accordance to the updated population of the distribution domains ( 401 - 403 ).