To whom correspondence should be addressed. E-mail: duanguiduo@ 163. com Duan Guiduo, born in 1981. She is now a Ph.D candidate at the School of Computer Science and Engi- neering of University of Electronic Science and Technology of China. She received her B.S. from Sichuan Normal University and M.S. degree from University of Electronic Science and Technology of China in 2003 and 2006 re- spectively. Her research interests include wavelet analy- sis, multiscale geometrial analysis and their application into digital watermarking.