摘要： 根据图像最大DCT归一化系数的近似不变特性，提出一种基于扩频编码的图像数字水印算法，采用扩频编码策略，在原始图像中嵌入较大容量的水印，对打印扫描攻击具有较好的鲁棒性。仿真实验结果表明，该算法能同时避免打印扫描过程产生的像素失真和几何失真，可以应用于电子印章和纸质证件的数字水印防伪。

关键词: 水印, 扩频, 安全性

Abstract: According to the similarity constant character of image maximum DCT normalization coefficient, an image digital watermark algorithm based on spread spectrum coding is proposed, which uses spread spectrum strategy to insert larger quantity of watermark into original images. It has better robustness to printing scanning attacks. Simulation experimental results show this algorithm can avoid both pixel distortion and geometry distortion at the same time produced in process of printing and scanning, and fit for applications of electronic seal and paperwork digital watermark anti-counterfeiting.

Key words: watermark, spread spectrum, security

中图分类号: 

• TP309