[1] Petitcolas F A P. Towards ‘robust’ watermarks-an introduction to digital watermarking, its state of the art and some key research topics. IEE Seminar on Secure Images and Image Authentication, 2000. 1/1～1/7

[2] Takai N, Mifune Y. Digital watermarking by a holographic technique. Appl. Opt., 2002, 41(5): 865～873

[3] Kishk S, Javidi B. Watermarking of three-dimensional object by digital holography. Opt. Lett., 2003, 28(3): 167～169

[4] Peng X, Cui Z Y, Tan T. Information encryption with virtual-optics imaging system. Opt. Commun., 2002, 212(4～6): 235～245

[5] Peng X, Cui Z Y, Tan T. Image encryption with virtual optics. Proc. SPIE, 2002, 4929: 96～104

[7] Goodman J W. Introduction to Fourier Optics. San Francisco: McGraw-Hill, 1968