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Computational and Mathematical Methods in Medicine
Volume 2012 (2012), Article ID 406349, 10 pages
http://dx.doi.org/10.1155/2012/406349
Research Article

Wavelet-Based Color Pathological Image Watermark through Dynamically Adjusting the Embedding Intensity

1Department of Dermatology, Affiliated Hospital of Weifang Medical University, Weifang 261031, China
2Department of Information Engineering, Weifang Vocational College, Weifang 261041, China
3School of Computer Science and Engineering, Xinjiang University of Finance and Economics, Urumqi 830012, China

Received 24 September 2012; Revised 20 October 2012; Accepted 22 October 2012

Academic Editor: Kumar Durai

Copyright © 2012 Guoyan Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper proposes a new dynamic and robust blind watermarking scheme for color pathological image based on discrete wavelet transform (DWT). The binary watermark image is preprocessed before embedding; firstly it is scrambled by Arnold cat map and then encrypted by pseudorandom sequence generated by robust chaotic map. The host image is divided into blocks, and the encrypted watermark is embedded into the higher frequency domain of blue component. The mean and variance of the subbands are calculated, to dynamically modify the wavelet coefficient of a block according to the embedded 0 or 1, so as to generate the detection threshold. We research the relationship between embedding intensity and threshold and give the effective range of the threshold to extract the watermark. Experimental results show that the scheme can resist against common distortions, especially getting advantage over JPEG compression, additive noise, brightening, rotation, and cropping.