Semi-fragile image watermarking algorithm based on visual features

In order to improve the invisibility and the robust ness of semi-fragile watermark,at first the paper puts forward the idea which embedded watermark based on the attacks´ characteristic, then the characteristic and its representation in DWT transform domain based on visual feature model, finally the Quantized Central Limit Theorem which applies to adjusting the coefficients i n general transform domain. These all make semi-fragile watermark embedded through dynamic quantization achieve the greatest robustness. It gives DWT coefficient redressal algorithm and the best restore probability of the pixel value adjusting in experiments when the images are under attack. It leads up to a better invisibility of carrier image and a better robustness to the image processing, such as JPEG compression, noise ad ding, filtering, and a larger amount of embedded information. What´s more, the watermark bits are quarter of original image s size, and it can ascertain the position of vicious attack exactly.