Image Encryption And Watermarking Based On The Joint Transform Correlator Architecture

In the past 50 years, optical information processing has been a rising subject. The invention of holography in 1948, the establishment of the optical transfer function in 1955, and the birth of highly coherent laser light source in 1960 are three events in the history of modern optics and are also the basis of optical information processing. In fact, the optical Fourier transform constitutes the theoretical framework of optical information processing. Nowadays, the optical image encoding and hiding is a very important research subject in the information processing and security field, and has wide application prospects in personal information protection, intellectual property protection and so on. Different from traditional information encryption technology based on mathematics and computer, the optical information security technology has many advantages of multi-dimensional, high-capacity, high robustness and inherent parallel processing, etc. Therefore, it is significant for us to make efforts on the development of optical encoding technology. In this paper, the double random phase encoding (DRPE) and the digital watermarking that based on a holographic technique are discussed in detail and a new digital watermarking technique which is based on the Joint Transform Correlator (JTC) architecture is proposed. Theoretical analyses and experimental results have shown the feasibility and validity of our system. The contents of this dissertation are organized as follows:In Chapter 1, a brief introduction to optical encryption and image processing including its research progress is given. Research methods and basic theories that used in this thesis such as Fourier transform and fractional Fourier transform, and spatial filtering are also emphasized in detail.In Chapter 2, the classical DRPE technique based on the 4f setup is firstly introduced and some numerical simulation results are given for illustrations. By extending the DRPE into the fractional Fourier domain, the security can be improved while the conjugate key is still essential for decryption. In practice, the requirements of optical alignment and the conjugate key can be removed by combining the JTC architecture and DRPE. The theoretical analyses and experimental simulation results are given to demonstrate the superiority and feasibility.In Chapter 3, the digital watermarking based on the holographic technique is described in detail. Simulation results show the feasibility and efficiency. Additionally, a new image encryption and watermarking method that based on a JTC architecture is proposed. With this technique, the information embedded in content image can be easily recovered. The theoretical analyses and computer simulations are presented to show the validity and efficiency of our system.Finally, our works are outlined and some noticeable blanks to be done are proposed with our expectation for future.