Method, System and Apparatus for Determining Alignment Data

A method of determining alignment data for a target frame and a reference frame. Patch data is received for each of a plurality of reference patches of the reference frame. The patch data comprises a reference direction of a feature in an associated reference patch and a reference signal corresponding to a projection of reference patch image data in a direction substantially perpendicular to the reference direction. A shift between at least one of said reference patches and a corresponding target patch in the target frame is determined using the reference signal associated with the reference patch and a target signal corresponding to a projection of the target patch image data in the direction substantially perpendicular to the reference direction associated with said reference patch. The alignment data for the target frame is determined using the determined shift for the reference patch.