1. A method of filtering an image dataset, comprising the steps of: providing an N-dimensional medical input image dataset acquired with ultrasound; applying a filtering algorithm to the input image dataset, wherein the filtering algorithm is essentially unvarying over the dataset, to thereby obtain a filtered image dataset; wherein this step may be repeated with different filtering algorithms to thereby obtain further filtered image datasets; providing a pre-determined spatially varying weighting function between the input and the at least one filtered image dataset; computing a weighted sum of the input image dataset and the at least one filtered image dataset, thereby using the spatially varying weighting function, in order to obtain an output image dataset, wherein the N-dimensional input image dataset contains image data in the form of pixel/voxel values, and the spatially varying weighting function is independent of the pixel/voxel values of the input image dataset, and that the spatially varying weighting function depends on the geometry of the input image data set, namely the distribution and configuration of its pixels/voxels in space, wherein the input image dataset has a spatially varying pixel/voxel size.