US Patent 7819324 Reflective decoders for use in decoding optically encoded images

A reflective decoding device is provided for use in decoding an encoded image comprising a latent image encoded using at least one encoding parameter. The device comprises a substrate with a reflective surface portion having a surface topography comprising a predetermined pattern of topographical features. The predetermined pattern is configured with at least one geometric characteristic corresponding to the at least one encoding parameter so that placement of a light-transmissive sheet having the encoded image formed thereon over the predetermined pattern of topographical features allows the latent image to be viewed.