Image scrambling algorithm based on image block and zigzag transformation

Image scrambling has wide application field in the protection of image information and secret. To achieve a satisfactory level of security, this paper introduces a color image scrambling algorithm based on image block, extended zigzag transformation and bit exchange technology. First, the algorithm converts the three-dimensional color image into two-dimensional gray image using matrix transformation according to the order of each component of image, then divides the image into blocks and completes block matching in couple, finally, the image is converted to cipher image using matrix transformation after permutation, substitution and bit exchange. Experiment simulations and theoretical analysis show that the algorithm can completely reach good scrambling effect and has the advantages of a large space of keys, high security, strong robustness and high sensitivity.