Securing color image by using bit-level modified integer nonlinear coupled chaos model in Fresnel diffraction domains

•An novel optical color image cryptosystem is presented by using biter-order modified integer nonlinear coupled chaos model in Fresnel diffraction domains.•A biter-order modified integer nonlinear coupled chaos model (INCCM) is designed to enhance the security of the proposed cryptosystem.•Some parameters in the encryption process are regarded as the extra keys to improve the security of the cryptosystem.