Abstract: An image watermarking algorithm in a discrete cosine transform domain based on QR code and grey relational analysis is presented in this paper. Literal information is encoded with a QR code as the digital watermark, and the watermark image is scrambled before embedding. The host image is divided into some non-overlapping blocks, and each block is processed with a two-dimensional discrete cosine transform. According to the correlation among image pixels, non-smooth regions of the host image are selected to embed watermark information by computing a double-direction grey correlation degree. Watermark embedding is selected from two schemes. One is based on the singular value decomposition (SVD), and the other is based on the orthogonal triangle decomposition (QR decomposition). Contrast experiment results show that the watermarking algorithm named QR code-GRA-SVD using the watermark embedding scheme based on singular value decomposition not only ensures the imperceptibility of the watermarking algorithm but also owns strong robustness. 

Key words: Watermarking, Discrete Cosine Transform, QR Code, Grey Relational Analysis, Singular Value Decomposition