In this paper we propose a practical blind detection multibit watermarking system. The proposed system is analogous to code division multiplexing in spread spectrum communications. Performance improvements with respect to existing multibit systems are obtained by means of informed embedding. With informed embedding we exploit perceptual modeling by using a wavelet-based multiplicative mask and exploit the digital content information to improve watermark detection. We implemented the proposed system for fragile and semi-robust multibit watermarks. The obtained results con.rm the good system performance considering watermark properties of fidelity, efficiency, data payload and robustness against valumetric distortion sources.