Ohtsubo Junji, Fujimoto Ayano
Faculty of Engineering, Shizuoka University, Hamamatsu, Japan.
Appl Opt. 2002 Aug 10;41(23):4848-55. doi: 10.1364/ao.41.004848.
A method of image encryption and decryption is proposed for optical security systems. A phase-coded image to be encrypted together with a random phase pattern is Fourier transformed and the result of the complex-valued data is used as an encrypted pattern. The decryption is simply performed by an inverse-Fourier transform for the addition of the encrypted pattern and the Fourier transform of the random phase. The intensity of the inverse-Fourier transformed image gives the exact result forthe decryption. Further, the binarization of the encrypted pattern is performed for the easiness of the optical and electronic readout of the images, and it also gives rise to the enhancement of the degree of security for the encryption. The binary pattern is optimized by a statistical iteration technique and an excellent decryption image is obtained by the optimization.
提出了一种用于光学安全系统的图像加密和解密方法。将待加密的相位编码图像与随机相位图案一起进行傅里叶变换，复值数据的结果用作加密图案。解密则通过对加密图案与随机相位的傅里叶变换之和进行傅里叶逆变换简单地完成。傅里叶逆变换图像的强度给出解密的精确结果。此外，为便于图像的光学和电子读出，对加密图案进行二值化处理，这也提高了加密的安全程度。通过统计迭代技术对二值图案进行优化，并通过优化获得了出色的解密图像。
