Digital watermarking using multiresolution wavelet transform

A novel technique for digital watermarking of still image based on the concept of wavelet transform is proposed. This algorithm takes advantages of multiresolution signal decomposition to obtain the frequency components of the image. Unlike most previous tree-based wavelet methods that embed a watermark into multiple subbands to enhance the robustness, the proposed method embeds a visually recognizable watermark pattern by modifying the single middle-frequency part of the original image. The experimental results show that the proposed method keeps image fidelity and is robust to common image processing operations, such as JPEG/JPEG 2000 lossy compression, filtering, and incorporating attacks. Some quantitative measures are adopted to objectify performances. Compared with other known watermarking schemes, the proposed method demonstrates its potential for reliable and secure copyright protection technique of multimedia data.