Patent Document ID: 7913923
Application ID: 12025756
Patent Status: 1

Claim One:
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.