By blending holographic imaging and 3D computer graphics, synthetic holography offers new possibilities in visual effects and image composition, some of which are impossible to conceive with any other medium. The multiple points of view and the ability to display content linked to the positions and movements of the observer makes synthetic holography a medium for which there is a whole new pictorial language to develop. This paper describes a series of experiments that shows the particularities of synthetic holography and deduces a few principles in image composition for computer generated holograms. In synthetic holograms, many image composition elements operate in a singular manner. The reversibility, decentralisation, simultaneity and synchronisation of content, the variability of alignments, the relationship between volumes and void, depth clarity and the spatial zones, temporal incoherence and the effects of time-smear, are all linked to the structure of the hologram and the movements of the observers. The optical characteristics of synthetic holograms have an impact on content choices. By understanding the elements of composition, the structure of multiple viewpoints perspective and the dynamics of observation in movements, the holographic artist can compose images that may lead spatial representation into new territories.
