【作者】 乔威；

【导师】 袁操今； 张永安；

【作者基本信息】 昆明理工大学 ， 光学， 2013， 硕士

【摘要】 近年来,随着计算机、数字图像处理和全息术等相关技术的进步,加密和防伪技术得到了较大的发展。然而技术的进步在促进加密和防伪发展的同时,也为伪造、仿冒者提供了高科技的造假技术。加密技术在信息安全领域中处于核心地位,而光学信息处理技术具有速度快、容量大、并行性等优点,并且能够提供诸如相位、波长、空间频率等多种加密维数,利用光学方法对图像进行加密逐渐成为国内外研究的热点。在这些研究中,双随机相位加密技术因其较高的安全性能而得到国内外学者的广泛兴趣和关注。本文开展的工作如下：首先,概述了光学信息加密技术在信息社会发展中的作用以及其重要性。回顾了光学信息加密技术尤其是基于双随机相位编码的加密技术的国内外研究与发展状况,并对双随机相位编码技术其本身存在的一些问题进行分类讨论其不足之处和目前的解决办法,随后介绍了本文中涉及的光学加密系统用到的一些基础知识以及全息技术的发展与分类。其次,基于全息理论设计了一种采集数字全息图像的实验光路系统,使用CCD对全息干涉条纹进行数字化记录和存储,借助MATLAB软件,使用计算机对实验所记录的数字全息图进行计算机模拟再现,得到了较好的再现结果。随后详细介绍了基于4-f系统的双随机相位编码技术和基于菲涅耳变换的双随机相位编码技术的基本原理,并利用计算机模拟这两种加密方法对采集的全息图进行加密。最后,基于4-f双随机相位加密系统,利用计算全息技术使经4-f双随机相位加密系统加密后的图像以计算全息图的形式保存,在提取保存在全息图中的加密图像时,利用衍射再现的方法来提取原始加密图像,再经4-f系统解密得到解密图像。随后进行计算机仿真实验,并得到了良好的结果。接着针对这种方法进行稳定性测试,分别从抗剪切、抗噪声两个方面对提取加密结果的影响进行分析和讨论,并进行计算机仿真实验,证实了该方法具有良好的抗剪切、抗噪声能力。更多还原

【Abstract】 The encryption and anti-counterfeit technology has been greatly developed with the technological advances in computers, digital image processing, holography and so on in recent years. The technological advances promote the encryption and anti-counterfeit development and simultaneously provide a high-tech counterfeit technology for counterfeiters. The encryption technology is at the core position in the information security field. The optical information processing technology has the advantages of large capacity, fast speed, parallelism and so on, and provides encryption dimensions, such as phase, wavelength, spatial frequency and so on. Image encryption carried out through using the optical method gradually becomes a research hotspot at home and abroad. The double random phase encryption technology is widely interested and concerned by scholars at home and abroad because of its high securityThe main research works are described as follows:(1) The effects and the importance of the optical information encryption technology in the development of the information society are summarized. The domestic and foreign research and development state of the optical information encryption technology especially the double random phase encoding based encryption technology are reviewed, the disadvantages and present solutions of the double random phase encoding technology are discussed in a classified manner, and then the development and the classification of some basic knowledge and the holographic technology of the optical encryption system referred in this paper are introduced.(2) An experimental optical system for acquiring digital holographic images is designed based on the holographic theory, the holographic interference fringes are digitally recorded and stored by using CCD, and the computer stimulation reappearance of the digital holograms recorded in the experiments was carried out through using a computer by means of MATLAB software, so a better reappearance result is obtained. The double random phase encoding technology based on a4-f system and the basic principle of double random phase encoding technology based on Fresnel transform are introduced in detail, and the computer simulation experiments are carried out through using the holograms acquired in the experiments.(3) Combined with the4-f double random phase encryption system, the images encrypted by the4-f double random phase encryption system are stored in the computed hologram form through utilizing the computed holographic technology, the original encrypted images are extracted through utilizing the diffraction method when the encrypted image stored in the hologram are extracted, encrypted images are obtained through4-f system decryption system, and then the computer stimulation experiments are carried out, so good results are obtained. Stability measurements are carried out against the above encryption method, the influence of the encryption extraction results are analyzed ad discussed from the shear resistance and the noise resistance respectively, and the computer stimulation experiments are carried out, so a case that the method have good shear and noise resistances is confirmed.更多还原