Abstract: The present disclosure discloses an image encryption method based on multi-scale compressed sensing and a Markov model. According to the difference in information carried by low-frequency coefficients and high-frequency coefficients of an image, different sampling rates are set for the low-frequency coefficients and the high-frequency coefficients of the image, which can effectively improve the reconstruction quality of a decrypted image. The decrypted image obtained by the present disclosure has higher quality than the decrypted image generated by the existing scheme, and a better visual effect and more complete original image information can be obtained.

Abstract: The present disclosure discloses a method for encrypting a visually secure image based on adaptive block compressed sensing and non-negative matrix decomposition. Firstly, the Tetrolet transform is performed on the plain image, then the sparsity degree is optimized on the sparsity matrix and the matrix scrambling is performed, such that the sparsity degree in each block region of the image matrix is equalized. Then according to the image information, the sampling number of the block region is calculated, the measurement matrix is constructed and optimized, and the image is compressed by using the optimized measurement matrix. The compressed image is then scrambled and diffused to complete the encryption process. Finally, the image information is embedded into the carrier image through non-negative matrix decomposition to obtain a visually safe ciphertext image. The decryption process is the inverse of the encryption process.

Abstract: The present disclosure discloses an image encryption method based on multi-scale compressed sensing and a Markov model. According to the difference in information carried by low-frequency coefficients and high-frequency coefficients of an image, different sampling rates are set for the low-frequency coefficients and the high-frequency coefficients of the image, which can effectively improve the reconstruction quality of a decrypted image. The decrypted image obtained by the present disclosure has higher quality than the decrypted image generated by the existing scheme, and a better visual effect and more complete original image information can be obtained.