Practical image hiding method using a phase wrapping rule and real-valued decoding key

We propose a practical image hiding method using phase wrapping and real-valued decoding key. A zero-padded original image, multiplied with a random-phase pattern, is Fourier transformed and its real-valued data denotes an encoded image in the embedding process. The encoded image is divided into two phase-encoded random patterns which are generated based on the phase wrapping rule. The imaginary part and the real part of these phase-encoded random patterns are used as a hidden image and a decoding key, respectively. A host image is then made from the linear superposition of the weighted hidden image and a cover image. The original image is simply obtained by the inverse-Fourier transform of the product of the host image and the decoding key in the reconstruction process. The embedding process and the reconstruction process are performed digitally and optically, respectively. Computer simulation and an optical experiment are shown in support of the proposed method.