摘要
提出了一种基于嵌入式小波编码的水印算法 .该算法根据 Watson关于小波系数量化噪声可见性研究的一些结果 ,将水印自适应地嵌入到小波变换的不同分辨率和不同方位的重要系数中 .水印的检测是分级渐进地进行的 ,从而提高了水印检测的效率 .文中实现了两种不同形式的水印 :标志图象的水印和伪随机序列的水印 .实验结果表明 ,该水印算法对图象处理和压缩等运算有较强的鲁棒性 .
Watermarking is one of the current copyright protection methods that have recently received considerable attention. In this paper, we introduce a wavelet transform based watermark casting scheme for digital images. The proposed method searches the significant coefficients across subbands to embed the watermarks into the significant wavelet coefficients. The watermark is adaptively weighted in different subbands according to the recommended mask values of wavelet coefficients by Watson. The current quantization threshold for each subband is also used as the weighting function of the embedded watermark. The fidelity of the watermarked image can be adjusted by using a weighting factor of the cast watermark. The casting and detecting of watermarks is hierarchical. In the case when the received image is not distorted significantly, the calculation of cross correlations with the whole size of the image may not be necessary, therefore much of the computational load can be saved. Experimental results show that the DWT based watermark approach can provide an excellent protection under various attacks.
出处
《中国图象图形学报（A辑）》
CSCD
北大核心
2002年第2期105-110,共6页
Journal of Image and Graphics
基金
国家自然科学基金 ( 6 0 0 75 0 0 2 )
北京市自然科学基金 ( 4 992 0 0 2 )
北京市教委科技发展计划基金
