A Performance Analysis of Spread-Spectrum Watermarking Based on Redundant Transforms

Spread-spectrum watermarking, in which random noise is added to transform coefficients and detected with a correlation operator, has become a preferred paradigm for many watermarking applica-tions. This paper analyzes the performance of such a watermark-ing system when the underlying transform is a tight frame rather than a traditional orthonormal expansion. The analysis indicates that a tight frame offers no inherent performance advantage over an orthonormal transform in the watermark-detection process de-spite the well known ability of redundant transforms to accommo-date greater amounts of added noise for a given distortion. 1