A Robust Wavelet-Domain Watermarking Algorithm for Color Image

This paper presents a chaos-based watermarking algorithm in the wavelet transform domain for color images. In contrast to conventional approaches, in which the wavelet transform coefficient is used for watermarking and the whole image is transformed into frequency coefficient, the wavelet transform is applied only to local subblock. DWT is used to transform the subimage, which is extracted from the original image randomly. And then the watermark image is adaptively embedded into part of the subband coefficients by computing their statistic characteristic. Without using the original image, the watermark is extracted by computing the statistic summation of the watermarked detail coefficients, where the threshold is chosen. Simulation results show that the proposed method possesses high fidelity and high robustness, especially under the typical attack of geometric operations