Perceptual Model-based Robust Image Watermarking Technology

With the rapid development of computer tech and Internet, most of multimedia data (such as digital image, video and audio, etc.) can be downloaded over the Internet. This brings conveniences to our working and daily lives. But at the same time it makes those multimedia data be easily copied, altered and redistributed without any permission from the copyright owner. This could lead to great loss of copyright owner. Thus, it is an urgent subject to safeguard information and intellectual property of digitized multimedia products.As an effective mean to protect copyright of multimedia information, digital watermarking technique has been widely researched and applied. This thesis focus on the digital image watermarking algorithm in the wavelet domain based on the previous research.Innovations of this thesis were given as follows.(1) According to the frequency masking, luminance masking and texture masking of image, an adaptive watermark embedding was designed by using the wavelet transform, thus a robust image watermarking was proposed based on the improved visual perceptual model in the wavelet domain. The experimental results demonstrate the effectiveness and the good robustness of the present method.(2) An adaptive quantization-based image watermarking with Watson model in the wavelet domain was presented. Based on the properties of luminance and frequency of image, the correlation of wavelet coefficients was considered. Thus we took full advantages of the decorrelation and energy compaction of discrete cosine transform, and the multi-resolution of wavelet transform, an adaptively watermark embedding was designed based on the Watson perceptual model. Experimental results confirm the algorithm can be effective to resist attacks covers JPEG compression, scaling, rotation and Gaussian filtering etc.