相位恢复算法用于分区复用多图像加密的研究

衍射投影效应明显降低了基于双相位编码的多图像加密系统的性能.提出分区复用技术来解决这一问题.待加密的多个图像被放置于各个输出平面的不同区域,于是相邻两个输出平面的秘密图像区域将错落开来,因而有效抑制了衍射投影所产生的噪声.在此基础上,重点研究了用于该系统的相位恢复算法.在完整的顺序迭代之后,对解密质量最差的图像进行逐一补偿,从而寻找到了更加符合多幅秘密图像客观特点的子循环次序.根据这一次序,用完整迭代后附加调节性迭代的方法或者完全更换迭代次序的方法,都能够在保留基本算法快速收敛优势的前提下,使多幅解密图像质量以及系统地复用容量得以整体提高.

Research on the Phase Retrieval Algorithm Used for Multiple-Image Encryption with Region Multiplexing

The effect of diffractive shadow evidently degrades the performance of the multiple-image encryption system based on double phase encoding. The region multiplexing is proposed to solve this problem. Since multiple images to be encrypted are located in different regions of each output plane, the noise arising from the effect of diffractive shadow can be suppressed. The corresponding phase retrieval algorithm is studied through theoretical analysis and computer simulations. After the whole iterations with the normal sequence, the image with the worst decrypted quality is compensated one by one. In this way, we can obtain the sequence of sub-iteration which is objectively suitable for the characters of multiple images to be encrypted. Based on this sequence, either an adjusting iteration after the whole iterations with the original sequence or completely changing the sequence of the whole iterations can be adopted. As a result, maintaining the advantage of the phase retrieval algorithm converging fast, both the quality of all decrypted multiple images and the multiplexing capacity of the system can be improved.