A computer program and a computer-implemented system and method for generating a two-dimensional image of a volume data set representing an object volume from a selectable viewpoint. An object volume data set includes voxel values ordered by voxels along a row that extends in a first direction, rows across a plane that extends in the first direction and a second direction, and planes through an object volume that extend in the first and second directions and a third direction. In response to the definition of a view vector defining a view direction with respect to a viewpoint, shear and warp mappings are determined, as is which of the first, second and third directions is closest to the view vector. Pixels of a two-dimensional sheared image having a plurality of lines of pixels are then determined from voxel values of the object volume data set identified by the shear mapping. Where the view vector is closest to the first direction, the shear mapping maps rows of voxels in the first direction onto lines of pixels of the sheared image. An output image is then determined by mapping pixels of the sheared image according to the warp mapping. This output image can be displayed, printed, sent to a remote location or otherwise communicated to a user.