Patent ID: 8276828
Filing Date: 2012-10-02
Classification: G06F,G06K

Abstract:
1. A method of decoding a coding pattern disposed on or in a substrate, said method comprising the steps of: (a) operatively positioning an optical reader relative to a surface of said substrate; (b) capturing an image of a portion of said coding pattern, said coding pattern comprising: wherein: the coding pattern has a physical layout defined by its tiling of contiguous grid cells, said physical layout belonging to a plane symmetry group that has t-fold rotational symmetry and translational symmetry with the grid cell as its unit cell; the coding pattern has a logical layout defined by its tiling of contiguous tags, said logical layout belonging to a plane symmetry group that has translational symmetry with the tag as its unit cell, but no rotational symmetry; there are ct possible registrations between the physical layout of the coding pattern and the logical layout of the coding pattern, each registration corresponding to a distinct combination of one of the t possible rotations of the physical layout of the coding pattern relative to the logical layout of the coding pattern and one of the c possible translations of the physical layout of the coding pattern relative to the logical layout of the coding pattern; any contiguous tag-shaped array of c grid cells contains cm control symbols, said cm control symbols encoding r the r the r there are ct distinct registration codewords, each corresponding to a distinct one of the ct possible registrations; the registration codeword of each contiguous tag-shaped array of c grid cells thereby uniquely identifies a registration between said tag-shaped array and the logical layout of the coding pattern; t=is an integer value of 2 or more; c=is an integer value of 2 or more; n is an integer value of 1 or more; and cnt≧r (c) sampling and decoding at least cnt control symbols contained in said imaged portion to provide r (d) constructing an imaged registration codeword of length r (e) identifying one of ct distinct registration codewords corresponding to said imaged registration codeword; (f) determining a registration corresponding to said identified registration codeword, said registration identifying a registration between a tag-shaped array of c grid cells at least partially contained in said imaged portion and the logical layout of the coding pattern; (g) constructing an imaged format codeword of length m using said determined registration and at least some of said r (h) identifying one of a plurality of distinct format codewords corresponding to said imaged format codeword; (i) determining a distinct format corresponding to said identified format codeword; and (j) using said determined registration and said determined format to decode data symbols sampled from said imaged portion.