Watermarking and Multimedia Security group showcases research at international conference
Thursday 1 May 2008
The Department's research is being showcased again this year at the 5th International IET Conference on Visual Information Engineering 2008 (VIE'08). The Watermarking and Multimedia Security group has two papers accepted for this prestigious conference in Xi'an, China from July 29th to August 1st.
Duan, G., Ho, A.T.S. & Zhao, X. (2008). A Novel Non-redundant Contourlet Transform for Robust Image Watermarking against Non-geometrical and Geometrical Attacks.
In contrast to conventional methods operating in the wavelet domain, a new robust watermarking algorithm using non-redundant Contourlet transform is presented in this paper. We explore the high degree of directionality and anisotropy of this transform to obtain a sparser image representation. Through experiments, we find that most of the energy relations between parent and children non-redundant Contourlet coefficients maintain invariant before and after JPEG compression. Performance improvement is obtained by means of embedding a watermark exploiting the modulation of the energy relations. Test results based on 16 set of attacks using 6 images are obtained. The results show that our non-redundant Contourlet method is highly robust to different kinds of attacks including non-geometrical and geometrical attacks. These include JPEG 2000 compression (as low as QF=10), 400 pixels circular shifting, and contrast stretching, (as low as 20%). Comparisons with two other wavelet methods further demonstrate the potential of the non-redundant Contourlet in digital watermarking applications.
Huang, W., Ho, A.T.S. & Pankajakshan, V. (2008). Watermarking-Based Content Authentication of Motion-JPEG Sequences
Content authentication has become an important issue for surveillance video. This paper presents a watermarking system based on Discrete Cosine Transform (DCT) for Motion-JPEG video authentication. To protect the integrity of the video object, a content-based watermark is embedded into the frames of the video. Robust watermark and semi-fragile watermark are used for temporal authentication and spatial authentication respectively. For analysis and evaluation, the system trades-off the robustness and the visual quality of the watermarked frames. The results show that the authentication rate almost reaches 100% in temporal authentication and is more than 98% in spatial authentication when the PSNR of watermarked frames is 36dB. It can robust to 55% JPEG compression and additive white Gaussian noise with variance of 0.002.