Method of imaging a coding pattern with data elements encoding by pulse-position modulation
First Claim
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1. A method of imaging a coding pattern disposed on a surface of a substrate, said method comprising the steps of:
- (a) capturing an image of a portion of said coding pattern, said coding pattern comprising;
a plurality of target elements defining a target grid, said target grid comprising a plurality of cells, wherein neighboring cells share target elements;
a plurality of data elements contained in each cell; and
a plurality of tags, each tag being defined by a plurality of contiguous cells, each tag comprising respective local tag data encoded by a respective set of said data elements,wherein said data elements encode data values by pulse position modulation;
(b) low-pass filtering said captured image so as to obscure said data elements and preserve said target elements;
(c) observing a perspective distortion of said preserved target elements due to a 3D orientation of said reader relative to said surface; and
(d) calculating a 2D perspective transform using said target elements.
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Abstract
A method of imaging a coding pattern disposed on a surface of a substrate. The method includes the steps of: (a) capturing an image of a portion of the coding pattern; and (b) low-pass filtering the captured image so as to obscure data elements in the image and preserve target elements in the image. The data elements encode data values by pulse position modulation, which facilitates the low-pass filtering.
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Citations
18 Claims
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1. A method of imaging a coding pattern disposed on a surface of a substrate, said method comprising the steps of:
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(a) capturing an image of a portion of said coding pattern, said coding pattern comprising; a plurality of target elements defining a target grid, said target grid comprising a plurality of cells, wherein neighboring cells share target elements; a plurality of data elements contained in each cell; and a plurality of tags, each tag being defined by a plurality of contiguous cells, each tag comprising respective local tag data encoded by a respective set of said data elements, wherein said data elements encode data values by pulse position modulation; (b) low-pass filtering said captured image so as to obscure said data elements and preserve said target elements; (c) observing a perspective distortion of said preserved target elements due to a 3D orientation of said reader relative to said surface; and (d) calculating a 2D perspective transform using said target elements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for imaging a coding pattern disposed on a surface of a substrate, said system comprising the steps of:
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(A) said substrate, wherein said coding pattern comprises; a plurality of target elements defining a target grid, said target grid comprising a plurality of cells, wherein neighboring cells share target elements; a plurality of data elements contained in each cell; and a plurality of tags, each tag being defined by a plurality of contiguous cells, each tag comprising respective local tag data encoded by a respective set of said data elements, wherein said data elements encode data values by pulse position modulation, and (B) an optical reader comprising; an image sensor for capturing an image of a portion of said coding pattern; and a processor configured for; low-pass filtering said captured image so as to obscure said data elements and preserve said target elements; observing a perspective distortion of said preserved target elements due to a 3D orientation of said reader relative to said surface; and calculating a 2D perspective transform using said target elements. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification