Spread-spectrum robust image watermarking for ownership protection

In this paper a new robust, spread-spectrum image watermarking approach is proposed. A two level wavelet transform is applied to the host image. Then three high frequency sub-bands in level 2 are selected and the watermark is embedded by an spread-spectrum technique. Selected sub-bands are divided into square blocks. Each block carries N_b bits of watermark information. Watermark data is added as uncorrelated pseudo-random sequences. In extraction process the same pseudo-random sequence is generated by the same seed. Experimental results approve robustness of the proposed method against JPEG compression, Gaussian noise and median filtering. The proposed method can be used in ownership protection specially where JPEG compression and Gaussian noise attacks occur.