Search

In this paper, we present a novel high capacity reversible image authentication scheme based on digital watermarking. The proposed technique slightly shifts the histogram of the difference image generated from the original cover image, thus modifies pixel values tenderly while obtaining a high embedding capacity. The distortion caused by embedding can be completely removed after the hidden data has been extracted if the watermarked image is authentic. The watermark data is blockwisely embedded so the tampered positions in a forgery image can be blockwisely detected wherever any disturbance is imposed. Experimental results demonstrate that the capacity of the proposed watermarking scheme is much higher than some state-of-art schemes with comparable PSNR values, while the computation complexity is kept low.

Digital watermarking has been proposed as a solution to the problem of copyright protection of multimedia files in networked environments. In this paper, a block-based adaptive image watermarking scheme using Just Noticeable Difference (JND) is proposed. The proposed scheme is performed in both pixel domain and Discrete Cosine Transform (DCT) domain. It first divides host image into 8×8 blocks. After that, it calculates the capacity of each block to embed information without being perceptible. This capacity can be determined by JND threshold, which is one feature of Human Visual System (HVS) model and it measures the smallest difference between watermarked and host image that is just detectable for human vision. The DCT coefficients of each block are adaptively modified according to the JND threshold values. Watermarks will be embedded in the modified DCT coefficients. Performance and experimental results of proposed scheme are presented. As expected, high robustness of watermarked images without image quality distortion can be achieved.

This paper introduces a novel approach of watermarking for copyright protection applications using the singular value decomposition (SVD) in the Dual Tree Complex Wavelet Transform (DT-CWT) domain. After applying the 2-level DT-CWT to the cover grayscale image, we apply the SVD to each high-pass subband obtained. The singular values in each subband are then modified by the singular values of the DT-CWT-transformed visual watermark. Modification in all subbands allows the development of a watermarking scheme that is robust to a wide range of attacks. Experimental results demonstrate that the proposed watermarking scheme is highly robust to various attacks.