S. Sudirman (UK)
Digital image watermark, wavelet transform, non-linear, high order polynomial
This paper presents the result of an investigation into the use of high order polynomial function when embedding signature data into digital images for watermarking purposes. Watermark signature, which is often in the form of a sequence of pseudo randomly generated number, is traditionally embedded using a linear function of the sequence and the image signal. The use of a high order or non-linear embedding function is proposed in this paper in order to improve the robustness of the watermark from attacks such as low pass filtering, additive noise and cropping. The embedding process is carried out in the wavelet domain as it is considered as the most robust domain for watermarking in the literature. Experiment results show that the correlation coefficient, a measure to detect the presence of a weak signal in a composite signal, produced using the proposed technique is in the order of magnitude higher than those produced via a traditional method for a given PSNR value. This in effect proves that the proposed technique is more robust that the latter.
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