Wavelet tree quantization for copyright protection watermarking

This paper proposes a wavelet-tree-based blind watermarking scheme for copyright protection. The wavelet coefficients of the host image are grouped into so-called super trees. The watermark is embedded by quantizing super trees. The trees are so quantized that they exhibit a large enough statistical difference, which will later be used for watermark extraction. Each watermark bit is embedded in perceptually important frequency bands, which renders the mark more resistant to frequency based attacks. Also, the watermark is spread throughout large spatial regions. This yields more robustness against time domain geometric attacks. Examples of various attacks will be given to demonstrate the robustness of the proposed technique.

I. Introduction

There has been great interest in applying watermarks to digital multimedia data for copyright protection, copy protection, image authentication, proof of ownership, etc. Watermarking techniques apply minor modifications to the original data in a perceptually invisible or almost invisible manner with the modifications bearing the watermark information. By detecting the existence of these modifications, we can prove the ownership and even trace an illegal copy source.