Modified Color Image Watermarking Scheme using DWT and DCT Coefficients of R, G and B Color Channels
Vasireddy Venkatadri · 2013
The rapid growth of networked multimedia systems has created an urgent need for copyright enforcement technologies that can protect copyright ownership of multimedia objects. Digital image watermarking is one such technology that has been developed to protect digital images from illegal manipulations. In particular, digital image watermarking algorithms which are based on the discrete wavelet transform have been widely recognized to be more prevalent 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 new scheme of how watermark bits are embedding into R,G and B color channels based on DWT-DCT coefficients. In this scheme color image is decomposed into R, G and B color channels. Later 2 level DWT is applied B channel and after that divide that image into 4X4 blocks then DCT is applied on the each block. Then select the middle frequency coefficients to embed the watermark bits. Performance evaluation results show that combining the two transforms improved the performance of the watermarking algorithms that are based solely on the DWT transform.