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A VQ-based robust multi-watermarking algorithm

We propose a new algorithm for digital image watermarking based on the characteristics of vector quantization (VQ). In contrast with the conventional watermark embedding algorithms to embed only one watermark at a time into original source, we present an algorithm to embed multiple watermarks for copyright protection. The embedding and extraction processes are efficient for implementing with the conventional VQ techniques. After embedding, the embedder would output one watermarked reconstruction image and secret keys associated with the embedded watermarks. These secret keys are then registered to the third party to preserve the ownership of the original source in order to prevent attackers from inserting counterfeit watermarks. Simulation results show that if there are some intentional attacks, all the watermarks could survive to protect the copyright. Therefore, we are able to claim robustness, usefulness, and ease of implementation of our algorithm.