J. Kobayashi and S. Komatsu: Preprocessing for Optical Personal Identification Method Using Three-Dimensional Information of Seals, Book of Abstracts, MOC'04 (10th Microopics Conference, Jena, Germany, 2004), p.55, F-42; Proc. MOC'04 (10th Microopics Conference, Jena, Germany, 2004), F_42.PDF.

We introduce preprocessing filters to personal identification method using three-dimensional information of seals. The seal is engraved with a design, and it is routinely used for financial transactions in some countries. The seal has three-dimensional information composed of the engraved design and engraved depth. Part of the three-dimensional information of the seal is captured as the two-dimensional image projected onto a CCD camera placed in an off-axis direction, and it is used as the key in our personal identification method. The three-dimensional shape of the seal is more difficult to imitate than its imprint. Therefore, our proposed method is expected to achieve a highly secure system. We introduce two kinds of preprocessing filters to the optical personal identification method that is based on the logarithmic joint transform correlation (LJTC). The projected image is first put through the median filter to reduce the noise in the projected image, and then it is put through the differential filter to enhance the edges contained in the image. The preprocessing image is identified by LJTC. The differences in the three-dimensional shape can be detected more sensitively with the present method.