Compression And Encryption Algorithm For Light Field Images Based On Space-frequency Domain

In the era of big data,the forms of data existence are becoming more and more diversified.Compared to traditional textual information,images have become the primary choice for people to transmit information due to their vivid image and intuitive simplicity.As an emerging immersive media,colour light field images are favoured by people because they have more information and can provide a better viewing experience.With the development of information technology and networking in society,the demand for access to and sharing of image information is also increasing,and therefore the security of image information in the process of storage and transmission is gradually attracting widespread attention.Light field images also pose great difficulties for transmission and storage due to their specific structure format and large amount of data.Therefore,the design of an efficient and secure light field image compression and encryption algorithm is of great significance to reduce the pressure on network transmission and storage.In this paper,the special structural characteristics of light field images are addressed,and the compression algorithm,chaotic system,DNA sequence,wavelet transform and encryption system on light field images are studied in depth.Based on this,we design a color light field image compression and encryption algorithm with high efficiency,good compression performance and good security.The main research contents and innovation points of this paper are as follows.Firstly,for the high dimensional characteristics and extremely high data redundancy of light field images,this paper takes full account of the spatial and angular information of light field images and designs a light field image compression algorithm based on angular domain features.The algorithm converts the light field sub-view images into EPI images,and compresses and encodes the data according to the data features of EPI images and the idea of predictive coding.The compression ratio of the algorithm for the whole EPI data set is 0.577 and the running time is 19.415 s.The results show that this algorithm has good compression performance and fast running speed.Secondly,the problem of low complexity and chaotic convergence of chaotic sequences generated by low-dimensional chaotic systems is addressed.In this paper,we propose an algorithm for self-controlled generation of chaotic sequences based on PWLCM chaotic systems,where the chaotic value of the previous chaotic sequence determines the initial value,control parameters and iteration number of the chaotic system that generates the next chaotic sequence,which effectively alleviates this problem.Thirdly,to address the problem that the existing light field encryption algorithms do not operate at a satisfactory speed,this paper proposes a color light field image encryption algorithm based on frequency domain DNA coding and self-controlled chaotic system under the premise of plaintext information as the key.First,the light field image is decomposed into sub-view images in the angular domain plane.Then,a low-frequency coefficient matrix and three high-frequency coefficient matrices are obtained in the frequency domain using a two-dimensional integer wavelet transform.A chunking operation is performed on the low-frequency coefficient matrix,an encryption operation is performed on the lowfrequency coefficient matrix using DNA coding and a self-controlled chaotic system based on PWLCM,a scrambling operation is performed on the high-frequency coefficient matrix,and then a reconstructed intermediate encrypted image is obtained using a two-dimensional integer wavelet inverse transform.Finally,a diffusion operation is performed in the null domain to obtain the final encrypted image.The simulation results show that this algorithm has the advantages of large key space,high operation efficiency,good encryption security,and strong resistance to various attacks.Finally,based on the proposed compression algorithm and encryption algorithm for light field images,the two algorithms are combined to further improve the effectiveness and speed of image transmission while ensuring the security of light field image encryption.A graphical user interface has also been created to make the light field image compression and encryption operation more tangible and convenient.