Effective interference reduction method for spread spectrum fingerprinting

The iterative detection method was proposed in IH2008 specified for the CDMA-based fingerprinting scheme which embedding procedure was additive watermarking method. Such a detection method is applicable for the multiplicative watermarking method that modulates a fingerprint using the characteristic of a content. In this study, we study the interference among fingerprints embedded in a content in the hierarchical version of Cox´s scheme, and propose the effective detection method that iteratively detects colluders combined with a removal operation. By introducing two kinds of thresholds, the removal operation is adaptively performed to reduce the interference without causing serious false detection.