Research On Adaptive Digital Image Watermarking Algorithms Based On Human Visual System

With the growth of network and multimedia technology, the copyright protection becomes more and more important. Digital watermark technology, as a main method of providing copyright protection, has been a hotspot in academic.This thesis mainly studies adaptive digital image watermarking algorithms based on human visual system (HVS). It introduces the basic concepts of the digital watermarking and application domains, explicates the representative characteristics of HVS and its importance in image watermarking, summarizes and classifies the existing adaptive image watermarking algorithms based on HVS, the innovation in this thesis is that different classifying rules of image are used and two kinds of new adaptive watermark algorithms based on HVS are proposed.The first algorithm uses a binary image as watermarking, the embedding strength varies with the features of the subblock of the image in DCT domain, and the Arnold matrix is also used in this algorithm to receive good security. The second algorithm uses gray image as watermarking, combines with JPEG compression method and classifies the subblock of image in spatial domain based on HVS, then embeds the pre-processed watermarking into original image adaptively. Emulating results show: the two proposed algorithms can resist several attacks such as JPEG lossy compression, addition of noise, median filtering, cropping, and contrast enhancement. The two methods can be used to copyright protection.