Yes, any separable filter causes grid artifacts that can be partially ameliorated by using a radial filter. My own pipe-dream is that we would use a triangular

Yes, any separable filter causes grid artifacts that can be partially ameliorated by using a radial filter. My own pipe-dream is that we would use a triangular grid (if you like, the Voronoi cells here are hexagonal pixels) for intermediate image representations. This is more spatially efficient and has nicer 2-dimensionnal frequency response than a square grid, and displays are so heterogeneous nowadays that we need to do some amount of resampling for output pretty much all the time anyway, and our GPUs are getting fast enough that resampling at high quality from a hexagon grid to a square grid for output should add only relatively cheap overhead.