Energy Quantization Modulation Approach for Image Watermarking

For copyright protection of digital image, we present an energy quantization modulation approach for digital image watermarking in this paper. First, we introduce the concept of local energy index of a coefficient block in approximation sub-band of an image. Second, an energy quantization modulation technique is developed to modulate the local energy index of each coefficient block. Moreover, in order to realize the energy quantization modulation technique, we employ a coefficient modification strategy that proportions the modification amount, and develop corresponding coefficient modulation rules. The energy quantization modulation approach not only can ensure good imperceptibility, but also can effectively improve the robustness against attacks. The proposed watermarking algorithm has simple computation complexity, and can effectively reduce image’s distortion. Performance of the proposed approach is evaluated under JPEG compression, additive noise, filtering, etc. It is shown that the proposed energy quantization modulation technique is superior to conventional quantization-based techniques.