A Blind Watermarking Algorithm Based on the Relationship of Coefficients in DCT Domain
DU Gao-feng · 2007
A blind watermarking algorithm based on the relationship of coefficients in the Discrete Cosine Transform(DCT) domain is proposed.Firstly,the original image is divided into non-overlapping 8×8-pixels blocks,and each block is independently transformed to frequency domain through 2D-DCT.Secondly,according to the relationship of DC and middle-frequency coefficients,a polarity matrix is obtained;and then compare the polarity matrix with binary watermark image after scrambling.Finally,the middle-frequency coefficients of the original image are modified in terms of the comparation result to get the watermarked image.The binary watermark is extracted from the watermarked image without the original image.The experimental results show that the algorithm is invisible and robust against the general image processing methods.