Color Image Encryption Technology Based On Spatial And Frequency Domain

Because of the advantages of expressing information intuitively and including large amount of information,digital images have become very important information forms that are widely disseminated and used on the Internet,bringing great convenience to people's work and life.The virtual nature and openness of the network make the image vulnerable to attack during the transmission process,causing unpredictable losses to individuals and even countries.Encryption is an effective means to protect images information security.However,the images have the characteristics of large amount of information,high redundancy and two dimensional storage.Therefore,it is critical to research and design secure,efficient encryption algorithms for images.In this paper,a new encryption algorithm is proposed that can double confuse the position and value of image pixels.In order to further improve the security of the algorithm,the new algorithm is combined with the chaotic system,and the color image is encrypted based on the integer wavelet transform and the Contourlet transform,and the algorithm is performed from the aspects of key sensitivity,histogram,and adjacent pixel correlation.Performance analysis.The simulation results show that the algorithm has high safety performance.The main works are as follows:(1)A color image encryption algorithm based on dual scrambling is proposed.Aiming at the shortcomings of the traditional scrambling algorithm based on pixel position,a dual scrambling algorithm based on pixel position and value is designed.In order to improve the security of the new algorithm,the new algorithm is combined with the one-dimensional Logistic chaotic system.(2)A color image encryption algorithm based on integer wavelet transform is proposed.Aiming at the advantages of better reconstruction effect and higher efficiency of integer wavelet transform,and combined with the dual scrambling algorithm proposed in this paper,color images are encrypted in the frequency domain.Firstly,the image is decomposed by integer wavelet transform,then the low-frequency components with abundant information are encrypted,and finally each component is reconstructed by wavelet to get the final encrypted image.Experimental results show that the scheme can achieve good encryption effect.(3)A color image encryption algorithm based on Contourlet transform is proposed.Because of the excellent features of Contourlet transform in image description,a color image encryption scheme based on Contourlet transform is proposed.The algorithm first performs Contourlet decomposition,then uses the new algorithm proposed in this paper to encrypt the low-frequency components,and finally performs Contourlet inverse transformation of each component to obtain the final encrypted image.Experimental simulation compares the encryption effect of two encryption schemes based on integer wavelet transform and Concourse transform.The results show that Contourlet transform has better encryption effect when applied to image encryption.