Reversible watermarking for image authentication using IWT

This paper proposes a 'Reversible Watermarking scheme for Image Authentication' (RWIA) using Integer Wavelet Transform that satisfies the requirements of imperceptibility, capacity, and robustness. The proposed algorithm hides the data and the bookkeeping information in the high frequency subbands of CDF (2,2) integer wavelet coefficients whose magnitudes are similar to a certain predefined threshold. Histogram modification is applied as a preprocessing to prevent overflow/underflow. The embedding technique is based on the parent-child structure of the transformed coefficients called quadruple wavelet tree (QWT). The paper provides a comprehensive analysis of the existing methods. The experimental results evaluated by the proposed technique on different grayscale images and a comparison with existing methods is found better. The watermark is extracted to an acceptable degree of normalized cross correlation even in the presence of attacks like geometric transformations and JPEG compression.