| At present,with the rapid development of computer technology,all kinds of multimedia information can be widely spread.In the initial stage,the content owner will take certain encryption measures to protect the transmitted information.With the development of cloud storage and big data technology,the research on reversible data hiding in encrypted image has gradually attracted the attention of researchers.People hope that the information can be embedded in encrypted images for transmission to protect the original carrier while protecting the security of the information.Focusing on the complexity of pixel blocks,improving the embedding rate of secret information and the quality of decrypted image,this thesis proposes two reversible data hiding algorithms for encrypted images with prediction error peak selection.The main contents of this thesis are as follows:This thesis analyzes the problem of too many variant pixels in bit XOR encryption based on Ge algorithm.On this basis,a reversible data hiding algorithm in encrypted images based on linear prediction error histogram is designed.The analysis shows that the use of mod256 encryption can reduce the difference between the decrypted pixels and the original pixels,effectively reduce the number of variant pixels and retain the redundancy between pixels,so as to effectively improve the visual quality of the decrypted image.In the data embedding stage,two peaks are determined by calculating the block prediction error.The fixed prediction error value 0 is used as one peak value,and the other peak value is randomly selected by the key to ensure that the algorithm has two different peak values and increase the embedding capacity as much as possible,and at the same time ensure the security of the algorithm.The experimental results analyze the rationality and effectiveness of the algorithm,as well as the changing trend of hiding capacity and visual quality at different embedding levels,and compare with other algorithms.In order to further improve the quality of decrypted image,a reversible data hiding algorithm in encrypted images is designed,which calculates the complexity of block pixel distribution and determines the embeddable pixels.The algorithm fully considers the distribution of pixels in the block and the correlation of adjacent pixels,calculates the complexity of pixels in the block,and divides into three cases: fully embeddable,locally embeddable and completely non-embeddable.Select the local pixels with low complexity as the embeddable data pixels,calculate the prediction error of all pixels,and select two peaks as the unified peak of each block.In order to improve the embedding capacity of the algorithm,the algorithm can also use histogram shift for multi-layer embedding of data.The experimental results show that when the number of data embedding layers is L = 1,the data embedding capacity of the algorithm is better than that of the comparison algorithm,and when L = max,the image quality of the decrypted image is still more than 30 dB.In order to verify the effectiveness of the proposed algorithm,an encrypted image reversible information hiding framework based on linear prediction peak selection is selected,a GUI simulation system is designed,and the algorithm is visually demonstrated and verified. |
