Watermark Detection Rate and Outliers

Spread-spectrum watermarking scheme adds random noise w into the host signal x to generate watermarked signal s. Blind detector computes inner product 〈w, s〉 or its variants and decides embedded bits by its sign of the inner product. Such detection method is not robust due to high false-positive or false-negative rate. This paper introduces a novel method to reduce detection errors considerably by excluding outliers in the signal. Stable and robust definition of outlier is adopted. Informed watermarking scheme for spread-spectrum is exploited to reduce false-positive and false-negative errors. Such detectors can also enhance detection rate in other watermarking schemes.