SYSTEMS AND METHODS FOR REGISTERING SCANNED DOCUMENTS

The scanned image registration systems and methods according to this invention register sets of scanned subimages of an original document into a composite scanned image of the original document. The subimages are formed by scanning portions of the original document on a scanner having a scan area, or window or footprint, that is smaller than the size of the document. An appropriate set of affine parameters, or more generally, transformation parameters, is obtained for each subimage relative to a fixed coordinate system. The set of affine parameters for each subimage defines the rotational and translational deformation necessary to place that subimage into the fixed coordinate system. The fixed coordinate system is preferably defined by selecting one of the subimages as a base image. The other images are then warped into registration with the selected base subimage based on the determined affine parameters. The base subimage and the warped other subimages are then combined to form the composite image of the original document. In particular, spatial averaging can be used to combine the base and warped subimages. Large format documents can thus be scanned using small window or footprint scanners.