DCT Watermarking Technique Using Image Normalization

This paper presents a modified algorithm for colour digital image watermarking. The 24 bits/pixel RGB images are used and the watermark is placed on the green channel of the RGB image. The embedding and extraction processes have been carried out using the discrete cosine transform DCT. Image normalization process has been integrated and used to improve the robustness against geometric attacks. Handwritten signature has been used as a watermark and embedded into the host image using different watermarking strengths. Comparison between the original and modified algorithm is presented. Experimental results show that the normalization process has been useful to overcome the drawbacks in the original algorithm and improve robustness against geometric attacks such as translation, rotation, and scaling.