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Novel watermark embedding technique based on human visual system

Good watermark needs to be perceptually invisible, undetectable without key and robust to spatial/temporal data modification. In this paper, we utilize the characteristics of the human visual system (HVS) where the response of visual cortex decomposes the image spectra into perceptual channels that are bands in spatial frequency. In the HVS, the spatial frequency domain is divided into octave-bands division in the radial axis. Based on the octave-bands division, a watermark is inserted into the channels which have same number of bits of the watermark. In doing so, more bits of the watermark are embedded into significant portions, which locate in the low-middle frequency region in the frequency domain. The above watermark insertion scheme gives a robustness because the watermark of significant portion can resist against strong attack of image. Experimental results show that the proposed method based on HVS method gives more robustness to the attacks compared with the conventional DCT, wavelet and DFT watermarking methods.