An optical image cryptosystem based on Hartley transform in the Fresnel transform domain

A novel method for image encryption and decryption based on Hartley transform in the Fresnel transform domain is presented. Different from the conventional method which requires lens to perform the Fourier transform for achieving Hartley transform, the proposed new optical architecture of Hartley transform is based on the Fresnel diffraction which requires no Fourier transform lenses. The position coordinate as well as the wavelength in the Fresnel transform is used as encoding keys that can ensure the sufficient information security. The main advantages of this proposed image security system are that it uses fewer optical devices and the decryption scheme is straightforward and more secure than the previous works.