Optic Image Encryption And Identity Verification Technique Based On Random Phase Modulation

In recent years, there have been steadily growing interests in the study of image encryption technique. Various progresses have been made in many areas. Among them, several successful image encryption techniques have been proposed. Because of the parallel and high speed processing of optical information processing system, it has been a new focus on research to study the image encryption by using optical methods. Among them, double random phase encoding techniques have received increasing attention at home and abroad for its high security.First of all, this thesis gives a general introduction to the application of data security system into the optical intention, which is followed by a discussion about the optical methods employed in safety authentication as well as a look into how double random phase encoding is being developed in recent years both at home and abroad. Then its improved methods are introduced in detail with the help of computer simulation verification.This paper gives a deep research into the optical security and encryption system, and makes some improvement. The main content includes:(1) Based on the study and analysis of the optical verification system for joint transform correlator, the random phase verification technique for POCS algorithm is studied, and the computer simulation is given. Some improvements are proposed in this paper on the basis of the above study and as a result the verification of unsymmetrical images is realized based on the conventional JTC.(2) This paper present a new color image verification algorithm based on Fresnel transform. The verification of color image is realized based on the phase retrieval algorithm. Theoretical analysis and results of computer simulation show that the proposed method is feasible.(3) In connection of hidden danger in security due to symmetric system, a novel color image encoding methods is proposed based on Fresnel transform encoding system without adding additional equipment. This method involves in pixel scramble technique and adopts full phase Fresnel transform encryption system and consequently it realizes the encryption of color image.The key space is significantly enlarged, and the adopting of non-linear achieves high security. Computer simulation and discussion are provide to show that the feasibility of the system.