一种基于PDF文档的数字水印算法

针对网络环境中对多媒体文本文档的篡改、盗版严重的问题,通过分析PDF文档的页面操作符以及具体参数的详细分析,提出并实现了一种基于PDF文档的数字水印算法.将水印信息添加到PDF(Portable Document Format)文档中文本字符码的特征信息中,通过检测从PDF文档中提取的水印信息与字符码的一致性来辨别该文档的真实性.试验结果表明,该算法具有很好的视觉透明性,而且便于出错信息的定位,是一种切实可行的数字水印算法.

Digital Watermarking Algorithm based on PDF Document

With the development of the network system, the sophistication and pirating of multimedia text documents become more and more popular. In this paper, the operators and material parameters of PDF (Portable Document Format) is analyzed in detail. So that a digital watermarking algorithm based on PDF document is proposed and implemented. Modifying the character spaces, the watermark with the features of the PDF character codes is embedded into the PDF document. By means of comparing the watermark distilled from the document with the features of the character codes, the document can be authenticated. The results demonstrated that the document with watermark has very good visual transparence and the location of the problematic message, such as character changing, is comparatively easier. So it is a feasible algorithm for PDF documents.