Abstract: Transmission holograms which produce a multicolor image when illuminated by white light are prepared by making the hologram as a number of superimposed component holograms of images of a subject. The images are formed either by an optical imaging system of by separate primary holograms of the subject. Each primary hologram is formed using coherent light of one wavelength to be seen when viewing the final transmission hologram, and the primary hologram is illuminated with coherent light of that wavelength when providing its image for the component hologram. The use of a sandwich of two photosensitive media, each containing at least one component hologram, to form the product transmission hologram is also described.