The New Algorithms Of Optical Image Encryption Based On Digital Holography

Optical image encryption is a new security technology born with the development of information society, using the features of light waves propagating through the space, such as diffraction, interference, refraction etc. to protect the security of image information. Since Javidi et. al. first proposed the double-random phase encryption technique which is based on 4 f system in 1995, optics information security has become a research field of much interest in the world. In comparison to conventional security system, optical image encryption system has the feature of high computational efficiency, high degree of parallelism and high dimension of encryption. In this dissertation, we mainly concentrate on a study deep into the new algorithms of digital holography based on the total variation image decomposition, constrained optimization and chaos theory. The work in this dissertation mainly includes:(1) We proposed an algorithm by combining the total variation based image deposition technique and generalized two-step digital holography for the reconstruction of wave front and the 3D profile. We extract the DC component from the hologram by replacing the mean filter and the low-pass filter in the original method with total variation image decomposition. The results of reconstruction yielded by our method show appreciable advantage when dealing with complicated profile and irregular wave front.(2) We proposed an algorithm for single shot double random phase digital holographic encryption based on a constrained optimization method. Not only can this algorithm deal with the problem of complex information, but also can cope with the dynamic optical encryption problem. Besides, the configuration of optical path is also simple. Compared to conventional Fourier method, the result yielded by our method shows advantages in aspects of both computational efficiency and image quality.(3) We proposed an encryption algorithm by combining the chaos base image encryption technique and generalized two-step digital holography. The new method heritages the advantages of the previous two —— low collision rate and high dimension of encryption, which is a bold endeavor and also a ground-breaking innovation solving the problem of high collision rate existing in the conventional double random phase digital holographic encryption.The purpose of this dissertation is using advanced algorithms of different areas into optical image encryption, proposing new methods and new technology of optical image encryption, and it may play a certain role on the research of phase-shifting digital holography encryption algorithm.