Stereo image encryption using vector decomposition and symmetry of 2D-DFT in quaternion gyrator domain

This paper introduces a novel encryption framework for stereo image. Firstly, both views of a stereo image are decomposed into four plates, which are constituted into a full quaternion matrix. Followed by block-wise quaternion gyrator transform, then different parts of the interim results are shared by orthogonal matrix and spliced together. According to the conjugate symmetry of two-dimensional discrete Fourier spectrum, a real-valued ciphertext can be obtained by superposing real and imaginary parts of the half spectrum. Among them, two-dimensional logistic-Sine-coupling map is employed for generating phase masks, rotation angles and shared coefficients, which greatly enhances the security of the cryptosystem. Numerical simulation results demonstrate the feasibility and reliability of the proposed encryption scheme.