1. 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.