Colour image watermarking in the complex wavelet domain

Digital image watermarking has become a very active research area. One key requirement in designing a watermarking system is that there should be no perceptible difference between the watermarked and original image, and the watermark should be difficult to remove or alter without damaging the host image. However, these two somewhat different requirements are usually closely related. This paper is concerned with an investigation of different methods to increase imperceptibility and robustness of colour watermarks embedded in colour host images using the Complex Wavelet Transform (CWT). The Complex Wavelet Transform was chosen because experimentation results from have shown the CWT to be more robust than other transforms under compression, additive noise, median and mean filtering attacks. Fusion based watermarking has been chosen since it provides a visual authentication of the watermark.