Public Key Method for Watermark Based on Dual-Transform Technique

A public key method for watermark based on dual transform technique is described in the paper. In order to meet the demands of intellectual property rights (IPR) protection on the world wide web ,both public watermark and private watermark are designed in this method. According to the characteristics and tree structure relations of the wavelet coefficients,the hybrid code of the two kinds of watermarks are embedded into the original image by combining principal component analysis (PCA) with wavelet transformation.The hidden datas are imperceptible and highly robust.Additionally,this method not only allows anyone to verify the public watermark which IPR authority designs but also guarantees that creator can extract his own private watermark as copyright evidence.,and so a new train of thought is therefore proposed for multimedia copyright protection.The experimental results show that the embedded watermarks are robust enough against the common image processing techniques.