1. A volume rendering processor for use with a voxel memory storing a volume data set of voxels constituting a three-dimensional representation of an object, comprising: voxel memory interface logic operative to continually retrieve the voxels from the voxel memory in a scanned order with respect to a Cartesian coordinate system having mutually perpendicular X, Y and Z coordinate axes, the Z axis being the axis more nearly parallel to a predefined viewing direction than either the X or Y axes, the set of voxels having equal Z coordinate values being referred to as a slice of voxels; and interpolation logic coupled to the voxel memory interface logic to continually receive the retrieved voxels therefrom, the interpolation logic being operative to continually calculate samples from the received voxels and to emit the samples sequentially in correspondence with the stream of received voxels, the samples being calculated such that (i) each sample lies along a corresponding imaginary ray extending through the object parallel to the viewing direction, (ii) each sample is the result of interpolation among a surrounding set of voxels in the Cartesian coordinate system, and (iii) the spatial frequency of the samples in one or more or the X, Y and Z directions is greater than the spatial frequency of the voxels in the same direction.