IMAGE DISPLAY MEDIUM, METHOD AND SYSTEM FOR PREPARING COMPOSITE IMAGE DISPLAY DATA

An image display medium displays an image including a first region having a first composite image. The first composite image includes a first display image and a first latent image. The first display image includes at least one of a first halftone dot image and a first line image having a first linearity. The first halftone dot image and the first line image have such densities as are not reproduced by copying. The first latent image includes at least one of a second halftone dot image and a second line image having a second linearity. The second halftone dot image and the second line image have such densities as are not reproduced by copying. The first and second linearities produce different moiré patterns when the first display and the first latent images are enlarged by a first common optical system.