Abstract: The digital watermarking is a process of information hiding. Digital watermarks allow users to legally use content, while adding security to the content to prevent illegal usage. Digital image watermarking algorithms based on the discrete wavelet transform have been widely recognized to be more powerful than others. This is due to the wavelets' excellent spatial localization, frequency spread, and multi-resolution characteristics, which are similar to the theoretical models of the human visual system. This paper presents a review on different digital image watermarking techniques based on discrete wavelet transform.

Keywords: Information hiding, discrete wavelet Transform, spatial localisation, multi-resolution, human visual system.