A secure partition-based document image watermarking scheme

Abstract

In this paper, a new document image watermarking method based on a secure partitioning scheme is proposed and tested. In the method, a document image is securely divided into weight-invariant partitions, followed by selectively modifying characters to embed watermarks. The high security of a watermark results from applying a probabilistic metaheuristic algorithm, namely the Ant Colony System (ACS), to approximate the involved Bottleneck Hamiltonian Path Problem to generate key-dependent image partitions. For better efficiency, the farthest point heuristic and the multi-scale strategy are introduced into the ant colony system. Our experimental results demonstrate that the proposed watermarking scheme is secure, efficient, and robust to common attacks. The proposed secure partition scheme could serve as a general framework to introduce high security to prevailing watermarking techniques. Copyright © 2010 Inderscience Enterprises Ltd.