A digital image watermarking algorithm based on discrete wavelet transform and Discrete Cosine Transform

The technique of digital watermarking is one of the valid methods for copyright protection. In this paper, we propose a digital watermarking algorithm with gray image based on 2 dimensions discrete wavelet and cosine transform in order to protect digital media copyright efficiently. We transform the image into discrete wavelet domain for three timely and split the image into sub-blocks, which is lower in horizontal direction and high in vertical direction, and then transform every block into discrete cosine domain, the watermarking components, which is also transformed into discrete cosine domain, are embedded into cover image. Finally, the secret image is obtained by reverse transform of wavelet and cosine domain. The experimental results show that the watermarking is robust to the common signal processing techniques including JPEG compressing, noise, lowpass filtering and cutting.