Preparation and display of derived series of medical images

Certain embodiments of the invention provide a computer apparatus and corresponding computer implement method for slab rendering from a three dimensional (3D) image data set of voxel data. Slab rendering is carried out on a stack of slabs of the same thicknesses in the 3D image data set. The whole stack of slabs is rendered together according to a desired filtering operation by applying a one dimensional van-Herk-Gil-Werman (vHGW) algorithm having a segment size one less than the slab thickness to strings of data that run through the whole stack.