Document containing security images

A document (1) carrying a latent image (2) comprising: a first image portion formed at a first color (4); a first latent image portion printed at a first line frequency at a first angle and a second color; and a second portion printed latent image at a second frequency lower than the first line frequency at the first angle lines and a third color, wherein a combined image the first latent image portion and the second latent image portion forms the same color as the first color (4).