OBLIVIOUS SCHEMES OF GHOST-BASED WATERMARKING FOR DCT COEFFICIENTS

In this paper we present oblivious schemes of ghost-based watermarking for DCT coefficients and examine the funda-mental resistance to some attacks. First we introduce a bipo-lar ghost model, which consists of a composite signal and its complementary signal, and formulate the power cepstrum for the model. Next we define the cepstral difference be-tween the composite and complementary signals to improve the cepstral performance, and examine some properties of the cepstral difference. After that, we explain two types of oblivious algorithms for the ghost-based watermarking in DCT domain taking the above properties into account. The experimental results for some test images show that the watermark information in each image can be detected sen-sitively by our schemes even when the watermarked images are subjected to processing technique such as clipping. 1