基于扩频的数字水印技术，水印信息分布于载体作品的多个频率系数，每个频率系数上负荷的水印能量很小，平衡水印的鲁棒性和不可感知性上的矛盾。-Digital watermarking based on spread spectrum technology, the watermark is found in a number of frequency coefficient vector works, each frequency coefficient on the load of the wate