1. A page width optical scanning system of the type wherein an image of a portion of a complete line of characters on a document is projected onto a plurality of groups of photosensitive means arranged in a single column, the groups to be scanned simultaneously, the photosensitive means extending parallel to character line length and wherein the output signals of all the photosensitive means in the array are periodically scanned and sampled, and wherein said system includes means for correcting scan pattern offset which comprises: multiplexing means having a plurality of inputs and a single output; means for delaying for selected periods, scanned data from each of said groups of photosensitive means, respectively, said periods being equal to the time required to compensate for scan pattern offset from each of the groups of photosensitive means; and means for transferring delayed data from each of said groups of photosensitive means, respectively, to individual inputs of said multiplexing means and produce scan corrected data at the output thereof.