Printing Media and Methods Employing Digital Watermarking

A method of processing a blank substrate prior to formation of a printed object, the method comprising encoding the substrate with a steganographic digital watermark pattern that does not impair subsequent use of the substrate, yet conveys plural-bit digital information, said pattern not being apparent to a human observer of the printed object, said steganographic pattern being detectable by visible-light scanning of the printed object to yield data from which the plural bit digital information can be recovered, wherein said plural bits of digital information correspond to the digital watermark pattern in accordance with an algorithmic transformation, and wherein the pattern is defined by generating a tile specifying one of N luminance values for each of plural different areas, consolidating the N values down to M, where M is less than N, and then forming lines between said areas in response to said consolidated luminance values.

A layered physical medium suitable to convey human-sensible text and/or image information to a human viewer, the medium having first and second exterior faces and including at least first and second layers, wherein the first layer is processed to define a first pattern, and the second layer is processed to define a second pattern, at least one of said patterns encoding machine readable data, said patterns yielding a pattern of contrast that can be sensed by an optical detector from an exterior face of said medium.

A method of marking a medium with a machine readable indicia that encodes plural binary bits, the method including printing a first portion of said indicia using a first technique, and printing a second portion of said indicia using a second technique, said two portions appearing indistinguishably-printed to a human viewer thereof, but having characteristics facilitating their distinction by machine analysis.