Richard P Dartez DeceasedBroussard, LA

5434956, Jul 18, 1995

Nov 4, 1992

7/971429

Myungsae Son - Rancho Santa Fe CA
Craig T. Johnson - San Diego CA
Richard M. Dartez - San Marcos CA

Hewlett-Packard Company - Palo Alto CA

G03C 1102

395105

Each two-dimensional alignment mark on a printing medium is found by using information about the whole mark area, or with respect to each of two different directions relative to the medium by using a distinctive two-dimensional pattern or characteristic of the mark; or by finding the mark centroid, or by scanning the mark region to obtain a two-dimensional representation for analysis--and preferably by combinations of these procedures. An image is then aligned and printed by reference to the mark so located. A previous image may also be preprinted in known relation with the mark, so that the new image is aligned with the preprinted one--sometimes on the same piece of medium. Preferably information used includes the mark's intended size, shape, areal disposition and other properties; and a two-dimensional search template is defined which matches the mark in at least one of these. A template position is then found that essentially maximizes areal intersection with the mark; this position is then treated as the mark position, for printing the new image. The invention preferably determines a position of the template along each of two directions in alternation--maximizing the areal intersection with respect to shifting along each direction, iteratively--until no significant increase is obtained.