Automatic Seal Imprint Verification Systems Using Edge Difference

In Asian countries, seals are widely used for authenticating the identity of a person or an organization. Therefore, the ability to efficiently verify whether a seal is either genuine or forged is important. Both rectangular and circular seal imprints are considered in this work. Geometric transformation is performed to align the perspective of the detected imprint image with the reference imprint. After the edge-differences between the reference image and the detected image are computed, a distance transformation is applied to extract several kinds of weighting matrices. The edge-difference images are weighted element-wise with the edge-difference images to calculate some predefined similarity metrics which serve as the input to the SVM (support vector machine). The imprint is then determined to be either genuine or forged. The experimental results show the effectiveness of the proposed verification approach.