A Hybrid Fractal-Wavelet Digital Watermarking Technique with Localized Embedding Strength

We propose a hybrid image watermarking technique making use of the advantages of fractal theory and wavelet transforms. Generally, the strength of watermarking is set to be a fixed value for the entire image. In our work the strength of watermarking in cover image is customized according to the complexity of image portions. The image is separated into complex and smooth regions based on fractal dimension. Fractal dimension measured with differential box counting (DBC) method is used to estimate the complexity of image portions. A higher value of embedding strength is used for complex regions, whereas a smaller embedding strength for smooth regions which are more sensitive to human vision system. Results show that the method produces imperceptible watermarks with higher detector response.