An invisible dual watermarking scheme for authentication and copyrights protection

This paper focuses on two problems, authentication and copyrights protection, faced by digital media in general and digital images in particular. We discuss how two algorithms defined separately can be combined to produce a secure digital camera which provides a solution to these problems. First, a robust quantization based wavelet domain scheme is applied to embed a robust watermark in the image for the purpose of owner identification. After that, a semi-fragile scheme is used to watermark the robust watermarked image for authentication. Experimental results show that recovered robust watermark had high correlation with the embedded robust watermark after different attacks. Under perfect conditions, recovered fragile watermark also showed perfect correlation with embedded fragile watermark, but after attacks, the similarity index dropped indicating that image is not authentic.