Concerning digital marking and reading of plastic items, useful in recycling

Abstract

A plastic item, such as a beverage bottle, conveys two distinct digital watermarks, encoded using two distinct signaling protocols. A first, printed label watermark conveys a retailing payload, including a Global Trade Item Number (GTIN) used by a point-of-sale scanner in a retail store to identify and price the item when presented for checkout. A second, plastic texture watermark conveys a recycling payload, including data identifying the composition of the plastic. The use of two different signaling protocols assures that a point-of-sale scanner will not spend its limited time and computational resources working to decode the recycling watermark, which lacks the data needed for retail checkout. In some embodiments, a recycling apparatus makes advantageous use of both types of watermarks to identify the plastic composition of the item (e.g., relating GTIN to plastic type using an associated database), thereby increasing the fraction of items that are correctly identified for sorting and recycling. A great number of other features and arrangements are also detailed.

1 . A system for processing a material stream including plural plastic objects, the system comprising:
 a conveyor belt;   one or more light sources positioned to illuminate plastic objects on the conveyor belt;   one or more cameras positioned to capture imagery depicting plastic objects on the conveyor belt;   watermark reading means for decoding from said imagery (a) first digital watermark information having a first signaling protocol, and (b) second digital watermark information having a second, different, signaling protocol; and   a sorter responsive to decoded watermark information.   
     
     
         2 . The system of  claim 1  that further includes clue detection means for triggering the watermark reading means in response to a promising excerpt of imagery. 
     
     
         3 . A recycling system including plastic food and beverage containers on a conveyor, and further including means for (a) diverting certain of said containers from the conveyor based on digital watermarks printed thereon, and (b) diverting certain of said containers from the conveyor based on digital watermarks formed by texturing on their plastic surfaces, wherein at least one of said containers conveys a first digital watermark formed by printing and a second digital watermark formed by plastic texturing, said first and second digital watermarks having different signaling protocols. 
     
     
         4 . A method of sorting plastic items in a material stream, including the acts:
 decoding first payload information from a machine-readable indicia on a first item, the decoded first payload information including a plastic recycling code indicating a type of plastic used in the first item;   sorting the first item from said waste stream based on said plastic recycling code included in the first payload information;   decoding second payload information from a machine-readable indicia on a second item, the decoded second payload information omitting a plastic recycling code, but including an identifier code;   based on said identifier code, obtaining a corresponding plastic recycling code from a database; and   sorting the second item from said waste stream based on the plastic recycling code obtained from the database.   
     
     
         5 . A container including a first digital watermark employing a first signaling protocol, the payload of said first digital watermark conveying data enabling a recycling system to determine a type of plastic from which the container is manufactured, characterized in that the container additionally includes a second digital watermark employing a second signaling protocol different than the first signaling protocol, the payload of said second digital watermark also conveying data enabling said recycling system to determine the type of plastic from which the container is manufactured, wherein the first and second digital watermarks differ in signaling protocol, yet both are useful for plastic recycling. 
     
     
         6 . The container of  claim 5  in which the first digital watermark is formed by 3D surface texturing, and the second digital watermark is formed by ink printing, wherein the first and second digital watermarks differ in formation and signaling protocol. 
     
     
         7 . The container of  claim 6  having front and back sides, wherein the first digital watermark formed by 3D surface texturing is present on both the front and back sides, and wherein the second digital watermark formed by ink printing is present on both the front and back sides. 
     
     
         8 . The container of  claim 6  in which the payload of said second digital watermark also conveys additional data enabling a point of sale apparatus to identify at least a name and a price for an item sold in said container, the payload of the first digital watermark lacking at least some of said additional data, wherein the first and second digital watermarks differ in formation, payload and signaling protocol. 
     
     
         9 . The container of  claim 5  in which the first digital watermark is formed by 3D surface texturing, including plural corner reflector-shaped indentations. 
     
     
         10 . A recycling method that includes the acts:
 capturing imagery depicting items in a material stream;   extracting a first digital watermark payload from imagery depicting a first item in said material stream;   based on payload data extracted from the first digital watermark, determining that the first item is made with a first type of reprocessable plastic;   extracting a second digital watermark payload from imagery depicting a second item in said material stream;   based on payload data extracted from the second digital watermark, determining that the second item is made with a second type of reprocessable plastic; and   sorting said first and second items from the material stream based on said determined types of plastic.   
     
     
         11 . The method of  claim 10  in which the first type of reprocessable plastic is polyethylene terephthalate, and the second type of reprocessable plastic is high-density polyethylene. 
     
     
         12 . The method of  claim 10  that includes extracting the first digital watermark payload from imagery depicting a label on the first item. 
     
     
         13 . The method of  claim 10  that includes extracting the second digital watermark payload from imagery depicting a 3D surface texture on the second item. 
     
     
         14 . The method of  claim 10  in which the first item is a bottle. 
     
     
         15 . The method of  claim 10  in which the first digital watermark payload extracted from the depiction of the first item includes a fixed message portion and a variable message portion, and said variable message portion includes plural fields, wherein one of said fields is a global trade item number (GTIN) field. 
     
     
         16 . The method of  claim 10  in which the first watermark payload includes a code identifying a plastic used in the first item, and the second digital watermark payload includes linking data, wherein the method further includes obtaining a code identifying a plastic used in the second item from a database, through use of said linking data. 
     
     
         17 . The method of  claim 10  in which the captured imagery comprises image frames, and the method includes analyzing each of plural pixel blocks in each of said image frames to find a clue suggesting presence of watermark data, and undertaking further image analysis when a clue is found, wherein the first digital watermark payload is extracted as a consequence of finding a first clue, and the second digital watermark payload is extracted as a consequence of finding a second clue. 
     
     
         18 . The method of  claim 17  in which at least two of said plural pixel blocks in an image frame partially overlap each other. 
     
     
         19 . The method of  claim 17  in which the first clue comprises detecting a region of pixels each having a value above a threshold value. 
     
     
         20 . The method of  claim 17  in which the first clue comprises detecting an ensemble of spatial image frequencies corresponding to a watermark reference signal. 
     
     
         21 . The method of  claim 17  in which the first clue comprises an output from a classifier indicating that a pixel block likely depicts a plastic item. 
     
     
         22 . The method of  claim 17  in which the first clue comprises an output from a classifier indicating that a pixel block likely does not depict a conveyor belt. 
     
     
         23 . (canceled) 
     
     
         24 . The method of  claim 10  in which the material stream is moved by a conveyor belt past a camera, wherein items on the conveyor belt enter a camera frame field of view along a first edge of the camera frame, and the method includes analyzing plural overlapping blocks spanning said first edge of the camera frame for clues indicating possible presence of watermark data, and undertaking further image analysis when a clue is found. 
     
     
         25 . The method of  claim 10  in which the first digital watermark is a watermark encoded according to a signaling protocol that represents payload data using a tile of 128×128 elements, and in which the second digital watermark is a watermark encoded according to a second, different, signaling protocol, which represents payload data using a tile of N×N elements, where N<128. 
     
     
         26 . (canceled) 
     
     
         27 . The method of  claim 10  that includes:
 assessing first and second pixel patches in the captured imagery to determine whether said patches likely depict a conveyor belt; 
 watermark-processing the first pixel patch as a consequence of said assessing determining the first pixel patch likely does-not depict the conveyor belt; and 
 not watermark-processing the second pixel patch as a consequence of said assessing determining that the second pixel patch likely does depict the conveyor belt; 
 wherein the first digital watermark is extracted from imagery comprising the first pixel patch. 
 
     
     
         28 . The method of  claim 10  that includes illuminating a first region of the material stream with a first illumination source, and illuminating a second region of the material stream with a second illumination source of a type different than the first illumination source, wherein the first digital watermark is extracted from depiction of the first item when illuminated by the first illumination source, and the second digital watermark is extracted from depiction of the second item when illuminated by the second illumination source. 
     
     
         29 . The method of  claim 28  in which the first illumination source emits illumination of a first color, and the second illumination source emits illumination of a second, different, color. 
     
     
         30 . The method of  claim 28  in which the first illumination source emits illumination of a first polarization state, and the second illumination source emits illumination of a second, different, polarization state. 
     
     
         31 . (canceled) 
     
     
         32 . The method of  claim 10  in which the material stream is moved by a conveyor belt at a speed, and the captured imagery comprises an image sequence captured at a frame rate, the sequence including first, second and third frames, the method includes the acts:
 analyzing plural image blocks in the first frame for a watermark clue; 
 detecting a watermark clue in a first image block of the first frame; and 
 identifying, in the second frame, one or more second image blocks for analysis based on said conveyor belt speed and said frame rate. 
 
     
     
         33 . The method of  claim 32  that further includes identifying in the third frame one or more third image blocks for analysis based on said conveyor belt speed and frame rate. 
     
     
         34 . The method of  claim 10  in which the first digital watermark includes a first reference signal and the second digital watermark includes a second reference signal, wherein the first reference signal has a correlation 0.2>r>−0.2, when confusion-tested with the second reference signal over a full range of affine transformations, namely with scales of the first reference signal ranging between 0.5 and 2.0 in increments of 0.02, and with rotations of the first reference signal ranging between −90 degrees through +90 degrees in increments of 1 degree, and with translations of the first reference signal ranging across every pixel of possible relative translation. 
     
     
         35 - 41 . (canceled) 
     
     
         42 . The method of  claim 10  in which each of said first and second items is marked with two different types of watermarks, namely (a) a first type of watermark printed on either the item or on a label applied to the item, said first type of watermark employing a first signaling protocol, and (b) a second type of watermark formed as a 3D texture in the surface of the item, said second type of watermark employing a second signaling protocol different than the first signaling protocol;
 wherein the method includes applying first and second different watermark reading algorithms to the captured imagery, the first watermark reading algorithm being adapted to read watermarks employing the first signaling protocol, and the second watermark reading algorithm being adapted to read watermarks employing the second signaling protocol; 
 wherein the method can sort the first and second items from the material stream based on either the first or second types of watermarks that mark said items, by payload data extracted by said respective first or second watermark reading algorithms. 
 
     
     
         43 . The method of  claim 42  that further includes applying said first and second different watermark reading algorithms to a common patch of pixels, wherein said common patch of pixels is analyzed both for the presence of the first and second digital watermarks. 
     
     
         44 . The method of  claim 42  in which the first watermark reading algorithm performs geometric synchronization using a first reference signal, and the second watermark reading algorithm performs geometric synchronization without using said first reference signal. 
     
     
         45 . The method of  claim 44  in which the second watermark reading algorithm performs geometric synchronization using a second reference signal different than the first reference signal. 
     
     
         46 . The method of  claim 42  in which the first signaling protocol of the first type of digital watermark represents the first payload by elements at positions in an array of encoding locations of a first size, namely 128×128 encoding locations, and the second signaling protocol of the second type of digital watermark represents the second payload by elements at positions in an array of encoding locations of a second different than the first size. 
     
     
         47 . The method of  claim 42  in which the first signaling protocol of the first digital watermark produces encoded square block patterns having a side dimension of 0.85 inches, and the second signaling protocol of the second digital watermark produces encoded square block patterns having a side dimension smaller than 0.85 inches. 
     
     
         48 . The method of  claim 42  in which the first signaling protocol of the first digital watermark has a first payload capacity, and the second signaling protocol of the second digital watermark has a second, different, payload capacity. 
     
     
         49 . The method of  claim 42  in which the first watermark reading algorithm performs a first type of error correction decoding, and the second watermark reading algorithm performs a second type of error correction decoding different than said first type of error correction decoding. 
     
     
         50 . The method of  claim 42  in which the first watermark reading algorithm employs a first key for descrambling, and the second watermark reading algorithm employs a second, different, key for descrambling. 
     
     
         51 . The method of  claim 42  in which the first watermark reading algorithm employs a first spreading sequence for demodulation, and the second watermark reading algorithm employs a second, different, spreading sequence for demodulation. 
     
     
         52 . The method of  claim 42  in which the first watermark reading algorithm employs a first scatter table, and the second watermark reading algorithm employs a second, different, scatter table. 
     
     
         53 . The method of  claim 4  that includes decoding the first payload information from the first item using a first digital watermark reading algorithm, and decoding the second payload information from the second item using a second digital watermark reading algorithm, the method further including sorting the first item to a first destination based on said plastic recycling code included in the first payload information, and sorting the second item to a second destination based on said plastic recycling code obtained from the database, wherein:
 the second destination is the same as the first destination; 
 the first and second plastic items are two instances of the same type of item; 
 each of said items is marked with both a first digital watermark and a second digital watermark, the first watermark being formed by a first process and the second watermark being formed by a second process different than the first process, and the first watermark employing a first signaling protocol and the second watermark employing a second signaling protocol different than the first signaling protocol; and 
 the first digital watermark reading algorithm is different than the second digital watermark reading algorithm, said difference including that the first algorithm is adapted to read watermarks employing the first signaling protocol, and the second algorithm is adapted to read watermarks employing the second, different, signaling protocol; 
 wherein an item can be sorted from the material stream based on reading of either the first or second watermarks, by said respective first or second watermark reading algorithms. 
 
     
     
         54 - 65 . (canceled) 
     
     
         66 . The method of  claim 10  in which the captured imagery includes a frame of imagery, and the method includes:
 examining a plurality of pixel blocks arrayed across said frame for clues indicating pixel blocks that may depict watermark data, said plurality of pixel blocks including a first pixel block, the pixel blocks included in said plurality having a first pixel spacing; 
 finding a watermark clue in the first pixel block, and as a consequence analyzing the first pixel block and also analyzing N pixel blocks around the first pixel block, said N pixel blocks having a second pixel spacing less than the first pixel spacing; and 
 extracting the first or second digital watermark payloads from one of said analyzed pixel blocks. 
 
     
     
         67 - 74 . (canceled) 
     
     
         75 . The container of  claim 5  including a printed label,
 the label being printed to convey said first digital watermark and encoding a payload P1 for sensing by a point of sale scanner in a retail store, the first digital watermark including a first reference signal that enables geometric registration of the first digital watermark for decoding by said scanner, the first reference signal comprising a first constellation of peaks in the 2D Fourier magnitude domain, said container further including a surface shaped to convey said second digital watermark and encoding a payload P2 that is different than P1, for sensing by a recycling apparatus, the second digital watermark including a second reference signal that enables geometric registration of the second digital watermark for decoding, the second reference signal comprising a second constellation of peaks in the 2D Fourier magnitude domain that is different than the first constellation of peaks, 
 wherein the first digital watermark is encoded as a pattern of variations in local luminance or chrominance, and the second digital watermark is encoded as a 3D texture pattern; and 
 wherein the different constellation of peaks in the second reference signal prevents a point of sale scanner that is attempting to read the payload P1 in a retail store from being confused by the presence of the second digital watermark. 
 
     
     
         76 . The container of  claim 75  wherein some but not all of the peaks in the second constellation overlap with peaks in the first constellation. 
     
     
         77 . The container of  claim 75  wherein none of the peaks in the second constellation overlaps with a peak in the first constellation. 
     
     
         78 . The container of  claim 77  wherein each of the peaks in the first constellation lies on a different radial line in a 2D Fourier magnitude plot of the first reference signal, and none of the peaks in the second constellation lies on one of said radial lines. 
     
     
         79 - 103 . (canceled) 
     
     
         104 . The system of  claim 1  in which the watermark reading means comprises a first watermark extraction module for extracting first digital data from patterns of a first format formed in the surfaces of textured plastic objects, the first watermark extraction module having an output coupled to the sorter, enabling the sorter to sort the objects based on said first digital data, the watermark reading means further comprising a second watermark extraction module for extracting second digital data from patterns of a second, different, format printed on said textured plastic objects, the second watermark extraction module having an output coupled to said sorter, enabling the sorter to sort the objects based also on the second digital data, wherein the second watermark extraction module is unable to extract digital data from patterns of the first format. 
     
     
         105 - 119 . (canceled)