为了进一步提高光学加密方法的安全性和抗攻击性能,利用双随机相位加密方法将图像加密,加密结果为一幅平稳分布的白噪声。利用水印技术的相关理论将加密结果隐藏在一张普通图像中,结合了加密技术和隐藏技术的优点,宿主图像并没有出现明显的降质,不容易引起攻击者的注意,具有较好的抗攻击性能。在解密过程中,提出一种改进解密效果的方法,经计算其解密图像的峰值信噪比(PSNR)达到了65.313,解密图像质量得到了显著的改善。同时通过计算机仿真得出加密结果能有效抗击裁剪等影响,具有很好的鲁棒性,而且实现方法简单,有较好的实用价值。

To improve the security and anti-aggressivity of optical encryption method, an image is encrypted by double random phase encryption method and the encryption result is a white noise of stationary distribution. And then, the encryption image is hidden in a common image by using the theory of watermark technology. That combines the advantages of encryption technology and hiding technology together. The result shows that quality of the original host image is not reduced obviously. Therefore, it is not easy to cause the attackers′ attention, and its anti-aggressivity is very good. In the process of decryption, an improved decryption method is presented. The peak signal-to-noise ratio (PSNR) of decrypted image is 65.313. Quality of the decrypted image is improved apparently. Meanwhile, the encryption image via computer simulation can effectively resist clipping. The method is very easy to adopt and its practical value very promising.