A novel nonlinear double image encryption based on affine transform and gyrator transform

摘要

We present a novel nonlinear double image encryption scheme by using matrix operation and affine transform in gyrator transform domains. Two original images are gyrator transformed independently and then phase- and amplitude-truncated to obtain two amplitude images and two phase keys. Then, permuted lower-and-upper decomposition is performed on two amplitude images, which results into six parts, L-i, U-i and P-i (i = 1, 2). Among these, L-1 combines with U-2 and L-2 combines with U-1 to form two new images, and P-i is served as the decryption key. The same operation mentioned above is carried out on two new images, then two newly obtained images will be further encrypted by affine transform, which results into two cipher images in the form of stationary white noise. The optical setup for encryption and decryption is suggested. Numerical simulations confirm the validity and safety of the proposed technique.