Object-based image watermarking technique using wavelets
We present a wavelet-based image watermarking algorithm that is able to embed the watermark information into objects within an image. In the proposed algorithm, the zerotrees in the wavelet coefficient domain corresponding to the selected object(s) are identified. Then the watermark is embedded into the bandpass wavelet coefficients with large amplitudes within these zerotrees by using an appropriate quantization process. The bitmap of the zerotrees corresponding to the selected objects, the wavelet used for the transform, and the parameters for the transform and quantization are chosen as the keys for the proposed algorithm. The effectiveness of the proposed watermarking technique and its robustness against some commonly encountered image processing operations are demonstrated through simulation studies.