Patent ID: 8244067
Filing Date: 2012-08-14
Classification: H04N

Abstract:
1. A computer-implemented method for identifying a constellation of alignment marks within an arrangement of computer readable marks in an image, the arrangement of computer readable marks including alignment marks and data carrying marks, wherein the alignment marks define a reference grid within the arrangement of computer readable marks and the data carrying marks are modulated with respect to the reference grid to encode data, said method comprising the steps of: selecting at least two marks from the arrangement of computer readable marks; determining a rotation center with reference to respective positions of the selected marks; determining rotated positions for each of the selected marks by rotating each of the selected marks by a predetermined angle about the rotation center; locating in the arrangement of computer readable marks, for each rotated position, a mark having a position that is less than a predetermined threshold from the respective rotated position; identifying the selected marks and the located marks as the constellation of alignment marks; and storing the identified constellation for use in decoding the data carrying marks.