Methods and arrangements involving substrate marking
First and second patterns are formed on a substrate. A spatial offset between the patterns is determined, and stored for later use in authenticating the substrate. (One or both of the patterns may convey steganographic information. One pattern may be printed, while the other may be embossed.) A smartphone can sense these patterns, determine the spatial offset, and check whether the determined offset matches the earlier-stored offset, to judge whether the substrate is authentic. Another arrangement effects serialization of product packaging by use of paired patterns (at least one of which is typically a watermark pattern) applied in a manner causing a spatial offset between the patterns to progressively vary along a length of a printed web. Still other arrangements involve substrates conveying patterns that degrade over time, e.g., indicating freshness or pressurization condition. A great variety of other features and arrangements are also detailed.
1. A method comprising the acts:
printing, on a substrate, a first tiled pattern comprising plural edge-adjoining first blocks;
embossing, on said substrate, a second tiled pattern comprising plural edge-adjoining second blocks;
cutting first and second pieces from said substrate;
determining a first spatial offset between the first and second patterns on the first piece; and
determining a second spatial offset between the first and second patterns on the second piece;
wherein the first and second spatial offsets are different, according to a progressive variation along a length of said substrate.
2. A method of fabricating a marked substrate comprising the acts:
printing, on a rolled substrate, a first pattern including plural first digital watermark tiles;
embossing, on said substrate, a second pattern including plural edge-adjoining tiles;
after said printing of the first and second patterns, identifying an excerpt of the rolled substrate, and determining spatial offset information that relates the first and second tiles on the excerpt; and
storing said spatial offset information for use in identifying the excerpt;
wherein the spatial offset information is not known until said determining act;
wherein forming of the first and second patterns is performed with first and second rollers, respectively; and
the first and second rollers have different diameters, causing the spatial offset between the embossed and printed patterns to progressively change along a length of the rolled substrate, during fabrication of the marked substrate.
3. The method of claim 2 wherein said printing and embossing acts are performed with a foil substrate.
4. The method of claim 2 wherein one of said printing and embossing acts is performed with a shaped roller.
5. A foil substrate that has been processed by the method of claim 2 .
6. The method of claim 1 in which the first pattern comprises a digital watermark pattern.
7. The method of claim 1 in which the forming act comprises embossing.
8. The method of claim 1 in which the forming and creating acts are performed on a foil substrate.
9. The method of claim 1 that further includes applying said first piece of substrate to a container of foodstuff as a label.
10. The method of claim 1 that further includes airtight sealing a container of foodstuff using said first piece of substrate.
11. The method of claim 1 that further includes:
capturing first and second images, depicting the first and second pieces of substrate, respectively;
determining said first and second spatial offsets from said captured first and second images; and
after said capturing and determining, using the first and second pieces of substrate in packaging first and second items of a foodstuff;
wherein the first and second items can thereafter by distinguished by said differing first and second spatial offsets.
12. The first piece of substrate produced by the method of claim 1 .
13. The method of claim 2 in which the act of identifying the excerpt comprises cutting the excerpt from the substrate.
14. The method of claim 2 in which the first roller defines a first integral number of tiles around its circumference, and the second roller defines a second, different, integral number of tiles around its circumference.
15. The method of claim 2 in which an axis along which tiles of the first pattern are arrayed, is inclined at a non-zero angle relative to an axis along which tiles of the second pattern are arrayed.
16. The method of claim 2 in which a first watermark tile of the first pattern encodes a first identifier, and a second watermark tile of the first watermark pattern encodes a second identifier different than the first.
17. The method of claim 2 in which the first roller defines an array of NxM watermark tiles, and each of said NxM watermark tiles encodes a different identifier.
18. An elongated substrate formed with first and second patterns, each pattern comprising plural edge-adjoining blocks, the first pattern comprising a steganographic digital watermark pattern, wherein the blocks of the first pattern are of a different size than the blocks of the second pattern, and the blocks are so-arranged that a spatial offset between a block of the first pattern and a proximate block of the second pattern progressively varies along a length of said elongated substrate, wherein two pieces cut from said substrate at different locations along its length will exhibit differing spatial offsets between the first and second patterns, serving as a form of serialization wherein said first pattern is a printed pattern and said second pattern is an embossed pattern.