Color image security system based on discrete Hartley transform in gyrator transform domain

摘要

A novel color image encryption algorithm based on Arnold- and discrete Hartley transform in gyrator transform domain is proposed. In this method, a color image is segregated into red, green, and blue channels. Each channel is permutated by first Arnold transform operation and the spatial distribution of pixel value is changed by first discrete cosine transform at image plane. The resulting image is encoded by discrete Hartley transform. The encoded information is again permutated by second Arnold transform and the spatial distribution of pixel value is changed by second discrete cosine transform at frequency plane, and finally gyrator transform is executed. The period and iterative number of Arnold transform, and transformation angles of gyrator transform in each channel are main keys, which increase the security of the proposed system. The proposed method can be well protected under chosen- and known plaintext attacks. Numerical simulations are conducted to illustrate the security, validity, and feasibility of the proposed method.