随机相位光学防伪中的前向迭代算法

The forward iterative algorithm in random phase encoding for optical security

本文采用前向迭代算法用在随机相位光学防伪中获得加密图象的Ｋｉｎｏｆｏｒｍ。该算法迭代过程中不再与被加密的原始图象进行比较，而是用加密图象振幅分布的均匀性控制迭代。这就克服了后向算法固有的局限性，在不增大每步迭代计算量的前提下，能够同时迭代获得一对实际存在的最佳加密相位列阵和加密图象的Ｋｉｎｏｆｏｒｍ。不仅如此，整个算法的收敛速度比后向算法快一个数量级，而且无论迭代结果的解密图象质量还是抑制噪声能力也都明显优于后向算法。

In this paper the forward iterative algorithm is reported which used in random phase encoding for optical security to get the kinoform of encrypted image.This algorithm is controled by the amplitude uniformity of encrypted image rather than comparing the original image encrypted with calculated result.As a result,this algorithm has overcome the intrinsic limitation belonged to the backward algorithm.There is possibility of obtaining a pair of optimal encryption phase array and kinoform of encrypted image with the same calculative capacity as backward algorithm in every iterative step.The convergence speed of forward algorithm is as fast as ten times of backward algorithm.Additionally,the decrypted image quality and noiseproof ability for the forward algorithm are also higher than the backward algorithms obviously.