Digital watermark method based on estimating harmonics frequency

In this paper, a new digital watermarking algorithm is presented. In this algorithm, the watermark embedded in image is constructed by several harmonics with known frequencies. When detected, the harmonics frequencies of the watermark extracted from the watermarked image will be estimated and compared with the original watermark. If the estimated and the original frequencies are equal within the permitted error limits, we say it is a successful detection. Because the harmonic estimating algorithm used in the paper can deal with complicated additive noise, the watermark algorithm presented in the paper is rather robust. Simulation results are provided to support the algorithm.