Precise verification of seal impressions

A method is proposed to verify seal impressions automatically. It has the following characteristics, and its effects are proved: (1) efficiency to judge genuine seals, even if the seals are degraded to certain extent, as in blur, scratchy or spotty impressions; (2) safety to reject false seals rigorously. The authors precise verification method uses small block information of seal conditions to cope with the above contradictory characteristics. Also, seal impression models are proposed to evaluate the trade-off by simulation. Parameters in the method are tuned using the models, and by experiments it is proved that the method has both efficiency and safety.