Semi-blind RGB colour image watermarking using DCT and two-level SVD

Abstract

This paper presents semi blind RGB color image wate rmarking using DCT and two-level SVD. First, RGB image is divided into red, green, and blue channels . The blue component is divided into blocks accordi ng to the watermark size. Second, DCT is applied to ea ch block to form a new block in the transform domai n. DC component is retrieved and assembled from each b lock to form a new matrix of 128x128 pixels. SVD is applied to the resultant matrix to obtain matrices, U, S and V. The watermark is embedded into the S matrix. The watermark can be extracted without orig inal host image, however, matrices U1, S and V1 are required. Experimental results indicate that the pr oposed algorithm can satisfy imperceptibility and i t is more robust against common types of attacks such as filtering, adding noise, geometric and compression attacks.