Image Watermarking Based on DC Component in DCT

The peak signal-to-noise ratio (PSNR) is a simple and widely used fidelity measure in the image watermarking. The position of watermarking plays an important role when the tradeoff between robustness and invisibility is considered. In the paper we analyze the mathematical relationship between the embeddable position and the PSNR in the DCT (discrete cosine transform) domain. We consider DC (direct current) coefficient to tradeoff robustness and invisibility. And a blind watermarking scheme is implemented through quantization index modulation (QIM) technology. Experimental results show watermarking is robust to common signal processing operation such as additional noise, filtering, resizing and JPEG compressing, and invisibility is satisfaction.