Self-authenticating documents with printed or embossed hidden images

1. A method of producing a self-authenticating article comprising:

providing a document comprising a substrate having an image receiving surface and a decoder lens having a lens frequency and being configured for optically decoding corresponding encoded indicia viewed therethrough, the document being configured so that the decoder lens may be selectively positioned to overlie the image receiving surface to decode encoded indicia formed thereon;

digitally encoding a source image to produce a rasterized encoded image having a raster frequency corresponding to the lens frequency; and

applying the encoded image to the image receiving surface of the substrate,

wherein the image receiving surface has a surface geometry that is initially substantially flat and the action of applying the encoded image includes reforming the surface geometry of the image receiving surface to include a plurality of alternating topographical features that collectively correspond to the encoded image.

2. The method of claim 1 wherein the document comprises a plurality of pages, a first page comprising the substrate and a second page comprising the decoder lens.

3. The method of claim 1 wherein the substrate is formed from a plastic paper substitute.

4. The method of claim 1 wherein the action of applying the encoded image includes applying a print medium to the image receiving surface.

5. The method of claim 1 wherein the action of reforming the surface geometry includes at least one of the set consisting of embossing the substrate, debossing the substrate, and removing material from the substrate.

6. The method of claim 1 wherein the decoder lens is a lenticular lens.

7. The method of claim 1 wherein the action of digitally encoding a source image includes:

providing a secondary image for use as a latent image to be embedded into the source image;

rasterizing the source image at the raster frequency to form a plurality of source image raster elements;

mapping the secondary image to the source image; and

shifting the source image raster elements at locations corresponding to content of the secondary image.

8. A self-authenticating article comprising:

a substrate having an image receiving surface;

a lenticular lens having a predetermined lens frequency, the lenticular lens being configured for optically decoding encoded indicia viewed therethrough and being attached to the substrate so that the lens can be selectively positioned to overlie the image receiving surface to decode encoded indicia applied thereto; and

an encoded image on the image receiving surface, the encoded image comprising encoded indicia formed as variations in surface geometry of the image receiving surface.

9. The self-authenticating article of claim 8 wherein the surface geometry variations comprise depressed and non-depressed surface areas that combine to define at least a portion of the indicia.

10. The self-authenticating article of claim 8 wherein the surface geometry variations comprise raised and non-raised areas surface areas that combine to define at least a portion of the indicia.

11. The self-authenticating article of claim 8 wherein the self-authenticating article comprises a plurality of pages, a first page comprising the substrate and a second page comprising the lenticular lens.

12. The self-authenticating article of claim 8 wherein the substrate is formed from a plastic paper substitute.