Optimum decoder for multiplicative spread spectrum image watermarking with Laplacian modeling
نویسندگان
1 Electrical Engineering Department, Sharif University of Technology, Tehran, Iran Advanced Communications Research Institute, Sharif University of Technology, Tehran, Iran
2 Electrical Engineering Department, Sharif University of Technology, Tehran, Iran Information Systems and Security Lab. (ISSL), Electrical Engineering Department, Sharif University of Technology, Tehran, Iran
doi
10.22042/isecure.2016.8.2.4چکیده
This paper investigates the multiplicative spread spectrum watermarking method for the image. The information bit is spreaded into middle-frequency Discrete Cosine Transform (DCT) coefficients of each block of an image using a generated pseudo-random sequence. Unlike the conventional signal modeling, we suppose that both signal and noise are distributed with Laplacian distribution, because the sample loss of digital media can be better modeled with this distribution than the Gaussian one. We derive the optimum decoder for the proposed embedding method thanks to the maximum likelihood decoding scheme. We also analyze our watermarking system in the presence of noise and provide analytical evaluations and several simulations. The results show that it has the suitable performance and transparency required for watermarking applications.
