A viewer moving up or down in front of a rainbow hologram sees changing spectral colors rather than different vertical perspectives. Because perspective effects are reproduced along one axis only, the subject will appear variously stretched or squashed when the hologram is not viewed at an optimum distance; this distortion may go unnoticed when there is not much depth, but can be severe when the distance of the subject from the plane of the hologram is very substantial.
A viewer moving up or down in front of a rainbow hologram sees shifting spectral colors rather than different vertical perspectives. Because perspective effects are reproduced along one axis only, the subject will appear variously stretched or squashed when the hologram is not viewed at an optimum distance; this distortion may go unnoticed when there is not much depth, but can be severe when the distance of the subject from the plane of the hologram is very substantial.