A system and process for determining the location of a captured image from a larger image is described. A non-repeating sequence may be folded into a non-repeating array in which the array is unique for every sub window of a given size. The image of the sub window may be captured and its location determined...http://www.google.co.uk/patents/US7386191?utm_source=gb-gplus-sharePatent US7386191 - Decoding and error correction in 2-D arrays
