| CPC H04N 23/00 (2023.01) [G06F 21/16 (2013.01); G09C 5/00 (2013.01); H04N 21/23892 (2013.01); H04N 21/44008 (2013.01); H04N 21/8358 (2013.01); H04L 2209/34 (2013.01); H04L 2209/608 (2013.01)] | 18 Claims |

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1. A recycling method that includes the acts of:
capturing 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 and, based on the first digital watermark payload, 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 and, 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 and second items from the material stream based on said determined types of plastic; wherein the captured imagery comprises image frames, each frame comprising plural pixel blocks and each pixel block comprising plural sub-blocks, and the method further includes the acts of:
analyzing pixel blocks in image frames to detect a clue suggesting presence of watermark data in said pixel blocks, and undertaking further image analysis of pixel blocks in which a clue was detected, wherein the first digital watermark payload data is extracted as a consequence of finding a first clue, and the second digital watermark payload data is extracted as a consequence of finding a second clue; and
detection of the first clue includes (a) computing, for each of the plural sub-blocks in a pixel block, an average value of pixels in the sub-block, to thereby yield plural sub-block average values for said pixel block, and (b) determining whether a majority of said average values for the pixel block is within 1, 2, 3 or 4 digital values of a peak value of a histogram of average values for said pixel block computed from plural previous frames.
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