Feature Watermarking in Digital Documents for Retrieval and Authentication

As a result of wide proliferation of digital media a lot of effort has been put to copyright protection, annotation and authentication. In this paper, we use invisible watermarking as a means for authentication of two-color text documents. Two variations have been made to the watermarking algorithm of Pan et. al.. We use this improved scheme as our watermarking method. This scheme uses a secret matrix key and therefore is completely secure. It also has a high capacity and does not degrade the quality of the host image. As we employ a loss-less method to compact important features and embed the coded features many times in the document image, the implemented system is able to detect image altercations in these features. It can completely retrieve them, even if a hacker has changed them in that document. Therefore, we can provide a valid authentication for the retrieved document.

Keywords:

Text Watermarking , Digital Document Authentication