Improvement of Image Watermarking System Based on Discrete Fourier Transform Using Fuzzy Logic

In this paper, a new image watermarking method in Discrete Fourier Transform (DCT) domain based on Fuzzy logic and human vision system is proposed. In first stage, input image is divided into 8*8 blocks and then the Fuzzy system allocates a coefficient for each block based on texture features and illumination which results in more robustness and clarification in watermark process. Next, by calculation of Discrete Fourier Transform (DFT) for each block, the resulting magnitude and phase are separated from each other and watermark is hidden in magnitude. The process of watermark extraction is blind which corresponds to higher security. The shortcoming of the general watermark system DCT-based is that the human vision system is neglected and therefore in order to prevent degradation of image quality, less robustness is resulted. The experimental results show that the proposed method provides more illumination and more robustness against cutting attacks, brightness and darkness of image, additive noise, image filtering and compression in comparison with popular DCT-based methods.