基于像素评估与运动补偿预测误差扩展的视频水印算法

Video Watermarking Algorithm Based on Pixel Evaluation and Motion Compensated Prediction Error Extension

目的为了解决当前视频水印技术因忽略了视频像素特性与时间的相关性,从而出现嵌入失真和水印容量较低等不足,设计一种基于像素评估和运动补偿预测误差扩展的自适应视频水印算法。方法首先,引入运动补偿预测误差扩展方法,预估每个视频帧的像素灰度值,从而获取其对应的运动补偿预测误差。再依据预测误差,计算像素的运动补偿局部标准差,将整个视频分割为平滑和非平滑子块。依据运动补偿局部标准差,结合像素选择阈值,从平滑块中选择出合适的像素用于嵌入水印。依据评估的水印容量与选择的视频像素,针对不同的像素,设计不同的水印嵌入机制,将水印信息隐藏到视频特定的像素中,通过完成边信息的嵌入,从而输出水印视频。最后,构建水印提取方法,从水印图像中检测出初始水印。结果测试数据显示,与当前视频水印方法相比,所提算法具有更高的水印容量和更低的失真度,其最大水印容量为2 bits,提取水印信息的PSNR值在40 dB以上。结论所提算法具有良好的不可感知性与较低的失真,在版权保护、信息防伪等领域具有一定的应用价值。

The work aims to design an adaptive video watermarking algorithm based on pixel evaluation and motion compensated prediction error expansion in order to solve these defects as embedding distortion and low mark capacity induced by ignorance of the correlation between the video pixel characteristics and the time in current video watermarking technology. Firstly, the motion compensated prediction error expansion was introduced to predict the gray values of each video frame and obtain the corresponding motion compensated prediction error. Then, the local standard deviation of pixel motion compensation was calculated according to the prediction error, and the whole video was divided into smooth and non-smooth sub-blocks. A pixel suitable for embedding watermark was selected from the video according to the local standard deviation of motion compensation and the pixel selection threshold. The watermark embedding mechanism was designed for different pixels based on the watermark capacity and the chosen video pixel to hide the watermark information into the video specific pixels. Finally, the watermark extraction method was constructed to recover the initial watermark information from the watermark image. The test data showed that this algorithm had higher watermark capacity and lower distortion when compared with the current video watermarking method. The maximum watermark capacity was 2 bits and the PSNR value of watermark information was more than 40 dB. This algorithm has good imperceptibility and low distortion, so it has a certain application value in copyright protection, information security and other fields.