基于压缩全息和空分复用的多彩色图像加密  

Multiple Color Images Encryption via Compressive Holography and Spatial Multiplexing

作　　者：张成[1,2] 许海涛 朱园园 汤俊 韦穗[1] ZHANG Cheng;XU Hai-tao;ZHU Yuan-yuan;TANG Jun;WEI Sui(Key Laboratory of Intelligent Com puing and Signal Processing,Ministry of Education,Anhui University,Hefei 230039,China;Key Laboratory of Modern Imaging and Displaying Technology,Anhui Universily,Hefei 230039,China)

机构地区：[1]安徽大学教育部智能计算与信号处理重点实验室,合肥230039 [2]安徽大学现代成像显示技术重点实验室,合肥230039

出　　处：《光子学报》2020年第9期168-179,共12页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.61501001,61605002,61301296,61377006);安徽省自然科学基金(No.2008085MF209);安徽省教育厅重大项目(No.KJ2019ZD04)。

摘　　要：针对现有光学加密方法进行彩色图像加密时加密容量低、解密图像失真度高等问题,提出一种基于压缩全息和空分复用的多彩色图像加密方法.在光学加密阶段,结合改进的Mach-Zehnder干涉仪与空分复用技术,通过不同的随机相位掩膜对多幅彩色图像进行同时加密,仅需单次曝光即可得到由多幅彩色图像加密的全息图.在解密过程中,由于记录全息图的过程可建模为压缩感知过程,使用两步迭代收缩/阈值算法即可求解.实验结果表明,提出的加密系统加密容量大,解密重建图像质量高,结合压缩感知理论,有效地消除了同轴全息中平方场项对解密重建性能的影响,解密图像平均峰值信噪比仅下降约2~5dB;密钥安全性高,随机相位掩膜与传播距离均起到密钥的作用,在随机相位掩膜错误或传播距离仅偏移0.25%时,便无法解密出原始彩色图像;且对噪声与遮挡性攻击具有良好的鲁棒性,解密重建性能随噪声增大下降趋势缓慢,加密全息图80%信息受到遮挡性攻击时,仍可取得良好的解密重建结果.A method of multiple color images encryption via compressive holography and spatial multiplexing is proposed to solve the low encryption capacity and high distortion of decrypted images when using existing optical encryption methods to encrypt color images.In the optical encryption step,multiple color images encrypted by different random phase masks.Combine space division multiplexing with modifying the Mach-Zehnder interferometer,which implemented for encrypting multiple color images simultaneously into one hologram by single shot.Combine space division multiplexing with modifying the Mach-Zehnder interferometer,which implemented for encrypting multiple color images simultaneously into one hologram by single shot.In the decryption step,the process of recording hologram can be regarded as a process of compressive sensing,the two-step iterative shrinkage/thresholding algorithm is used to solve the problem.The experimental results show that the proposed encryption system has a large encryption capacity and a high quality of decrypted color images,and the average peak signal to noise ratio only decreases about 2~5 dB of the decrypted images,which eliminate the influence of square field term in the on-line holography;and the random phase mask and the propagation distance both play the role as the key,which can provide high security.The color images can not be decrypted when the random phase mask is wrong or the propagation distance is only offset by0.25%;and it has good robustness to noise and occlusion attacks.The quality of decrypted images decline slowly with the increasing noise.We can still be obtain the good decrypted results,when 80%of the encrypted hologram information is under occlusion attack.

关 键 词：光学加密 压缩感知 全息术 彩色图像 单次曝光 相干测量 加密/解密过程 

分 类 号：O438[机械工程—光学工程]