Research On The Algorithm Of Optical Image Encryption Based On Digital Holography

With the rapid development of modern communication technology,the image transmission's security is becoming increasingly important.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.As a new encryption method,optical image encryption based on digital holography has been widely applied to image encryption in recent years because of its intrinsic advantages,which provide high-speed parallel processing and high dimension and a large amount of storage.First,the paper meanly summarizes the theoretical technology about the encryption of optical,then the paper introduces some kinds of classic optical encryption system.After explaining the fundamental principles.The system of image encryption based on digital holography is investigated further.Based on this,we analyze the in-axis phase shifting digital holography and off-axis digital holography succinctly and propose an algorithm of optical image encryption based on off-axis digital holography and random phase mask.We demonstrate image encryption and decrypting system using Fourier or Fresnel digital holography separately.Using interference with a wave from a phase mask,the encrypted hologram is recorded using a CCD camera digitally.This key hologram,the electronic key and the encrypted image all can be transmitted through communication channels conveniently.By changing the different encryption parameters,such as incident wavelength and diffractive distance,we analyze the performance of the algorithm.It proves that the method can encrypt image effectively.We also propose an angular-multiplexing optical image encryption scheme based on off-axis digital holography to achieve multiple-image encryption.By introducing reference plane waves with different incident angles at the output plane and placing random phase masks in the input plane.We accomplish multiple-image encryption and decryption.We analyzed the encryption and decryption quality.The method enhances the feasibility of the system and decrease the encryption complexity and precision requirement for random-phase mask.The proposed scheme is significant to the development of optical multiplexing encryption techniques.Numerical simulation experiments have been carried out to verify the reliability security the proposed methods.We use the PSNR(Peak Signal to Noise Ratio)and CC(Correlation Coefficient)to evaluate the performance of the proposed algorithm and analyze the sensitivity of key.These algorithms have less computation,simplified operation and great prospects of application.