Patent ID: 7463774

Claim:
A method of determining a portion of a document corresponding to a captured image, comprising: obtaining a captured image of a portion of a document, the document having a pattern that uniquely identifies different positions in the document; determining obscured areas of the document in which the pattern is at least partially obscured; designating a reference pixel in the captured image; identifying locations in the obscured areas of the document that may correspond with the reference pixel; comparing the captured image with different portions of the document, such that the reference pixel is compared with one or more of the identified locations; and based upon the comparison, determining an identified location in the document that corresponds with the reference pixel, wherein determining an identified location in the document that corresponds with the reference pixel further includes warping the captured image so that the scale and rotation of the captured image match the scale and rotation of the document; rotating the warped captured image at multiples of 90°; and determining a correlation value for each comparison of the image with a portion of a document.