Abstract: Watermarking plays an important role in the applications of copyright protection and data authentication. In this paper, we apply the commonly used discrete cosine transform (DCT), and embed two watermarks into color images. For the first watermark we choose the QR code, and for the second one we employ the binary random sequence. With the classification of watermarking, robust watermarking is suitable for copyright protection, while fragile watermarking aims at authentication purposes. We embed the two watermarks into the low and mid frequency bands, respectively. When intentional attacks are applied, the first watermark can be extracted, while no attack is applied, both watermarks can survive. Simulations have demonstrated the capabilities of multi-purpose watermarking with our method.
