Keizo NAKAYAMA and Junji OHTSUBO^1*

School of Science and Engineering, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan
¹Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561, Japan

(Received December 4, 2006; Accepted May 25, 2007)

In practical optical security systems we must consider various circumstances for reading and decrypting encrypted holograms. Binarization of the hologram is best suited for such applications because of the ease of handling encrypted data. However, the decrypted image is greatly degraded by binarization. Therefore, optimization of a binary hologram is essential in using such a technique. In this paper, we propose a fast optimization method of a binary encrypted hologram to obtain a good reconstruction based on the error correction algorithm. In the proposed method, multiple pixels of the binary hologram are simultaneously flipped for the optimization according to the priority for the correction. The time for the optimization is only 3% of that of the simulated annealing method.

Key words: optical security systems, optical encryption and decryption, optimization of binary hologram

^*E-mail address: tajohts@ipc.shizuoka.ac.jp