A Method to Estimate Watermark Invisibility before Embedding in DWT Domain

For invisible and robust watermarking schemes, estimation of watermark invisibility is necessary. Most of schemes estimate their watermark invisibility after watermark being embedded through experiments. In this paper, invisibility of watermark in DWT domain is analyzed. According to the properties of orthogonal DWT, we get the relation between variance of embedded watermark in DWT domain and the variance of noise it causes in spatial domain. Using this relation, we can estimate the PSNR of watermarked host image without experiments. This method is useful for watermarking scheme design. Experiments are done to testify the validity of this estimation method.