1. A method for segmenting an image, the method comprising: determining an initial estimation of a boundary between at least two components in a region of an image to be segmented; providing image data from the region of the image to be segmented, the image data representing quality values of a plurality of image elements of the at least two components; modelling the image data with a mixture of at least two statistical distributions, each statistical distribution having more than one parameter, and each component being associated with certain weights of the at least two statistical distributions in the mixture; estimating the parameters of the statistical distributions in the mixture; for each component, estimating the weights of the at least two statistical distributions in the mixture based on the estimated parameters and the image data of each image element; and optimizing the initial estimation of the boundary between the at least two components based on the estimated parameters and estimated weights.