Key-dependant decomposition based image watermarking

In this paper, we propose a novel image watermarking algorithm, which is based on the scheme where the watermark is embedded into projection of an image onto the secret set of key-dependant basis functions. We propose a key-dependant image decomposition method, which involves solving a bottleneck hamiltonian path problem by an ant colony optimization technique. Combined with the decomposition technique, the original scheme is significantly improved on the aspects of speed, capacity and security. In particular, our algorithm usually shortens the running time of the original scheme by a factor of several hundred.