Method of encoding a latent image

摘要

There is disclosed a method of forming a latent image. The method involves transforming a subject image into a latent image having a plurality of latent image element pairs. The latent image elements of each pair are spatially related to one another and corresponding to one or more image elements in said subject image. The transformation is performed by allocating to a first latent image element of each pair, a value of a visual characteristic representative of the one or more corresponding image elements of the subject image, and allocating to a second latent image element of the pair a value of a visual characteristic which is substantially complementary to the value of the visual characteristic allocated to the first latent image.