Patent ID: 7263224

Claim:
A method for determining a path of a pen tip within a document, the method comprising: (A) decoding extracted bits associated with a captured image to determine location coordinates of the captured image, by: (A)(i) obtaining the extracted bits that are associated with a captured array; (A)(ii) processing the extracted bits to determine whether the extracted bits contain at least one error bit and to determine the location coordinates if no error bits are detected; and (A)(iii) if the at least one error bit is detected, further processing the extracted bits to determine the location coordinates from a portion of the extracted bits, by: (A)(iii)(1) if an error bit is detected, selecting a different subset from the extracted bits, wherein at least one bit of the different subset is not one of previously correctly decoded bits; (A)(iii)(2) decoding associated bits of the different subset; (A)(iii)(3) in response to (2), determining whether another decoding iteration shall be performed; (A)(iii)(4) if another decoding iteration shall be performed, selecting another subset from the extracted bits wherein at least one bit of the other subset is selected from a set of wrongly decoded bits of each previous iteration and repeating (2); and (A)(iii)(5) if another decoding iteration shall not be performed, determining the location coordinates of the captured array, wherein the location coordinates are consistent with a local constraint; (B) in response to (A), if the location coordinates of the captured image cannot be determined by decoding, matching the captured image with image information of the document; and (C) mapping the path of the pen tip from the location coordinates of the captured image to the location coordinates of the tip of the pen.