Robust and Fragile Watermarking Techniques for Documents Using Bi-directional Diagonal Profiles

Abstract

A number of techniques have been recently proposed to prevent unauthorized user from illegal copying or redistribution of multimedia contents. One approach for copy protection is robust watermarking technique that purposes to resist several attacks such as signal processing, geometric distortion, etc. On the country to robust watermarking, the other approach is fragile watermarking that purposes to detect slight changes to the watermarked contents. In this paper we find out the problems of a marking and identification scheme for document images using one directional diagonal profile that we proposed. And then we suggest robust watermarking technique to resolve these problems using bi-direction diagonal profiles; left-directional diagonal profile and right-directional diagonal profile. According to this robust watermarking technique, it can reduce the side information, which needs in watermark extraction procedure and find the pixel position on document image with only the indexes of bi-directional diagonal profiles. Finally, in addition to robust watermarking scheme, we suggest fragile watermarking technique that can locate or characterize the forged region using the feature of bi-directional diagonal profiles and reverse process.