An Improved Robust and Adaptive Watermarking Algorithm Based on DCT

This paper proposes an improved watermarking algorithm based on DCT (Discrete Cosine Transform). We carried out the algorithm as described as follows. First, we extended both rows and ranks of the watermark by using the proposed method before the embedding stage. After expansion, Sine chaotic system is employed in encrypting the watermark. In the embedding stage, an effective and adaptive embedding method is proposed to embed the watermark into the blocked DCT coefficients. Experimental results demonstrate that the proposed algorithm in this paper works well in resisting both geometry attack and noise attack. It also does well in recovering the watermark after stego image suffered from JPEG compression.