Recycling methods and systems, and related plastic containers

A product container manufactured of plastic and including a first digital watermark pattern employing a first signaling protocol, a plural-symbol payload of said first digital watermark pattern conveying data indicating a type of plastic from which the product container is manufactured, characterized in that the product container additionally includes a second digital watermark pattern employing a second signaling protocol different than the first signaling protocol, the plural-symbol payload of said second digital watermark pattern also conveying data indicating the type of plastic from which the product container is manufactured, wherein the first digital watermark pattern and the second digital watermark pattern differ in signaling protocol, yet both are useful for plastic recycling;

• the first digital watermark pattern is encoded as a 3D texture pattern in a surface of the product container, and the second digital watermark pattern is encoded as a pattern of printed variations in local luminance or chrominance on a printed label conveyed by the product container;
• the first digital watermark pattern encodes a plural-symbol payload P1 for sensing by a recycling apparatus, the first digital watermark pattern including a first reference signal comprising a first constellation of peaks in a 2D Fourier magnitude domain;
• the second digital watermark pattern encodes a plural-symbol payload P2 that is different than P1, for sensing by a point-of-sale scanner in a retail store, the second digital watermark pattern including a second reference signal comprising a second constellation of peaks in the 2D Fourier magnitude domain different than the first constellation of peaks;
• and
• the first constellation of peaks in the first reference signal prevents a point-of-sale scanner that is attempting to read the plural-symbol payload P2 in a retail store from attempting to decode a payload from the first digital watermark pattern.

A recycling method that includes the acts:

• receiving imagery depicting items in a material stream;
• extracting first digital watermark payload data, comprising plural symbols, from imagery depicting a first item in said material stream;
• based on the first digital watermark payload data, determining that the first item is made with a first type of plastic;
• extracting second digital watermark payload data, comprising plural symbols, from imagery depicting a second item in said material stream;
• based on the second digital watermark payload data, determining that the second item is made with a second type of plastic;
• and
• sorting said first item and said second item from the material stream based on said determined types of plastic;
• wherein each of said first item and said second item is marked with two different types of watermark patterns, namely (a) a first type of watermark pattern printed on either the item or on a label applied to the item, said first type of watermark pattern employing a first signaling protocol, and (b) a second type of watermark pattern formed as a 3D texture in a surface of the item, said second type of watermark pattern employing a second signaling protocol different than the first signaling protocol;
• wherein the recycling method includes applying a first digital watermark reading algorithm and a second different digital watermark reading algorithm to the received imagery, the first digital watermark reading algorithm being adapted to read watermark patterns employing the first signaling protocol, and the second different digital watermark reading algorithm being adapted to read watermark patterns employing the second signaling protocol;
• wherein the recycling method can sort the first item and the second items from the material stream based on either the first type of watermark pattern or the second type of watermark patterns that mark said items, by payload data extracted by said respective first digital watermark reading algorithm or second different digital watermark reading algorithm;
• and
• wherein the first digital watermark reading algorithm performs geometric synchronization using a first reference signal, and the second different digital watermark reading algorithm performs geometric synchronization without using said first reference signal.