Digital Watermarking Algorithm based on PDF Document
Liao Ke-yu · Modern Computer · 2005
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.