基于离散余弦变换直流分量的盲视频水印方案

Blind Video Watermarking Scheme Based on Direct Current Component in Discrete Cosine Transformation Domain

利用离散余弦变换(DCT)直流系数稳定的特点,提出了一种通过调整视频图像的分块DCT直流系数来隐藏水印的方法.将选取的视频帧以8×8像素进行分块,根据掩蔽矩阵来选取需要嵌入的水印块.把选中的图像块再以4×4像素细分为4个互不重叠的小图像块,通过调整它们的DCT直流系数的值来嵌入水印.实验结果证明,所提方法具有很强的鲁棒性且计算简单,能抵抗缩放、帧删除、多次视频压缩、转换压缩编码格式、共谋攻击、删除行或列等有意和无意的攻击,特别是MPEG-2压缩比特率为4 Mb/s时,从3幅不同类型的图像中提取的水印相关值分别达到了0.996 1、0.996 1和0.986 3.

By using the stability of the direct current （DC） coefficient in the blocks of discrete cosine transformation （DCT）, the blind video watermarking method of modulating the DCT- blocked DC coefficients to hide the watermark was proposed. Firstly, the random selected video frames are partitioned into blocks with size 8 × 8, and the blocks embedding the watermark are selected by the mask matrix. Then every selected block is further divided into four non-lapped blocks with size 4×4. Finally, the watermark is hidden by modulating the DC coefficients of the four nondapped blocks. The watermark is spread before it is embedded in order to increase the robustness. Experimental results demonstrate that the proposed method is computationally simple, and robust against the intentional or non intentional attacks such as zooming, deleting frames, multiple compression, transition of compression standard, collusion attack, and deleting rows or columns. The correlation values between the original watermark and the extracted watermarks from I, P, B pictures are 0. 996 1, 0. 996 1 and 0. 986 3 respectively when the MPEG-2 compression bit rate is 4 Mb/s.