Digital watermarking of encrypted in-line holography

A new encrypted in-line holographic watermarking technique is proposed based on double-random phase encoding method,holography and digital watermarking.The proposed method includes two processes of encryption and decryption.In the encryption process,a digital watermark image is modulated by double-random phase encoding,and its in-line hologram is superposed on a content image.The watermark is recovered by means of holographic reconstruction and calculations in reverse order of encryption process without the information of the content image(blind detection).Analysis and computer simulation prove that the encrypted holographic watermark is valid,robust and secure.The watermark can be recovered from the watermarked images distorted by noise added,JPEG compression,part occluded and low pass filter.The conditions for superposing the hologram onto the content images are also investigated in detail