Canonical minimal-pixel hologram geometries are presented in the context of a generalized image relay system. We illustrate that the number of pixels ultimately depends only on the physical parameters of the displayed image (the Smith-Lagrange optical invariant). Various choices of synthetic optical geometries lead to pixel aspect ratios that are found to be good matches to available display technologies. We explore geometries in which the spatial light modulator is imaged at either the image-plane or the viewer-plane, or astigmatically imaged to both at the same time. This increases the variety of candidate aspect ratios considerably, and brings us close to a workable match with foreseeable optical technologies that will make holographic video a practical reality.