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.
Proc. SPIE. 4475, Mathematics of Data/Image Coding, Compression, and Encryption IV, with Applications
KEYWORDS: Signal to noise ratio, Image compression, Detection and tracking algorithms, Image processing, Error analysis, Interference (communication), Digital watermarking, Computer simulations, Image quality, Signal detection
Time-domain and frequency-domain spreading algorithms are presented in this paper. However, detection algorithm does not rely on correlation method, but based on patchwork method. Time-domain algorithm can survive translation and clipping attacks. Frequency-domain algorithm is robust against compression attack. Embedding and detection functions are presented. Simulation results show the effectiveness of the algorithms.