A novel scheme for selection of watermark strength in digital image watermarking based on harmony search algorithm

In this paper, selection of watermark strength in digital image using harmony search is presented. In image watermarking procedure, the image is divided into separate blocks and the watermark is embedded in the transform domain via the watermark strength and the inverse transform is carried out. Digital image watermarking has several requirements based on its applications. Transparency and robustness are two important requirements in many applications. These two requirements are in conflict and watermark strength controls them. Decreasing the watermark strength causes higher transparency and lower robustness and vice versa. Having these two features is not possible at the same time, further more it would be time consuming to determine the proper watermark strength by error and trial and using the optimization algorithms is of great importance in this case. The experimental results show that the proposed algorithm selects the proper watermark strength to have suitable transparency and robustness at the same time.