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Báo cáo sinh học: " Research Article Nonblind and Quasiblind Natural Preserve Transform Watermarking"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Research Article Nonblind and Quasiblind Natural Preserve Transform Watermarking | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2010 Article ID 452548 13 pages doi 10.1155 2010 452548 Research Article Nonblind and Quasiblind Natural Preserve Transform Watermarking G. Fahmy 1 M. F. Fahmy 2 and U. S. Mohammed2 1 German University in Cairo GUC New Cairo City 11835 Egypt 2 Department of Electrical Engineering Assiut University Assiut 71515 Egypt Correspondence should be addressed to G. Fahmy gamal.fahmy@guc.edu.eg Received 10 September 2009 Revised 10 December 2009 Accepted 10 March 2010 Academic Editor Robert W. Ives Copyright 2010 G. Fahmy 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. This paper describes a new image watermarking technique based on the Natural Preserving Transform NPT . The proposed watermarking scheme uses NPT to encode a gray scale watermarking logo image or text into a host image at any location. NPT brings a unique feature which is uniformly distributing the logo across the host image in an imperceptible manner. The contribution of this paper lies is presenting two efficient nonblind and quasiblind watermark extraction techniques. In the quasiblind case the extraction algorithm requires little information about the original image that is already conveyed by the watermarked image. Moreover the proposed scheme does not introduce visual quality degradation into the host image while still being able to extract a logo with a relatively large amount of data. The performance and robustness of the proposed technique are tested by applying common image-processing operations such as cropping noise degradation and compression. A quantitative measure is proposed to objectify performance under this measure the proposed technique outperforms most of the recent techniques in most cases. We also implemented the proposed technique on