Digital watermarking algorithm based on Kalman filtering and image fusion

A digital watermarking algorithm based on Kalman filter and image fusion is proposed. The digital watermarking can be viewed as a process that embedding a weak signal (watermark) to a strong signal (original image), so the process of watermarking can be viewed as a process of image fusion. In the proposed watermarking algorithm, the watermark embedding and extraction process are expressed as the state estimate process, and Kalman filter is used as an optimal estimation algorithm in the process of image fusion. An optimal estimation model is built according to the watermark image and the original image, and then the state equation and the corresponding measurement equation are built. The optimal estimation is archived in case of the minimum estimation error variance. Crossentropy and mutual information are used to evaluate the performance of image fusion. Experimental results show that the proposed algorithm has a good performance in both robustness and invisibility.