Multi-resolution image watermarking scheme in the spectrum domain

Many spectrum domain watermarking schemes have been proposed in recent years, but they seldom deal with the problem of progressively detecting the embedded watermark, which is desirable in some situations. This paper addresses this problem by embedding the watermark in the DCT domain of an image in a multiresolution way. The DCT coefficients are treated as wavelet transform coefficients, and each watermark bit is embedded into a block of coefficients repeatedly layer by layer using a wavelet watermarking scheme, so that the embedded watermark can be detected progressively. Furthermore, for the scheme to be robust against geometric transformations, a second spread spectrum circular watermark is embedded in the DFT domain. Experimental results show that this scheme is robust against common signal processing procedures such as compression, median filtering and additive noise, as well as geometric transformations such as rotation and translation.