Study On Adaptive Blind Watermarking Algorithem Based On Integer Wavelet Transform

Recently, with the popularity and the development of Internet, the copyright of digital image has aroused extensive interests, among which digital watermarking which is inserting copyright information into the data is deemed as an effective way for copyright protection. There are two watermarking schemes according to whether or not needing original image at the extraction processing. They are blind watermark schemes and non-blind watermark schemes.This paper describes in detail the basic theory of wavelet. Applying the good localized features in both the time domain and the frequency domain and the characteristics of multi-resolution analysis of the two-dimension DWT, This paper proposes a new blind watermark technique by adjusting the numbers of zerotrees derived from the integer to integer wavelet transform coefficients to embed and extract watermark based on EZW theory. For setting pre-defined thresholds is very important for performance of host image and in watermark processing, they are determined by experiment in most articles. In this paper, An adaptive blind watermarking algorithem based on image feature is presented. First, the host image is partitioned into 8 x 8 non-overlapped blocks. Second, we perform integer to integer wavelet transform on the selected blocks. Third, Integrating the Humanvisual System (HVS), The energy ratio feature and difference feature of each DWT transformed block is classified as different kinds, so the threshold of each block DWT can be adaptively determined. Last, the band where the coefficients will be changed is selected in according to region homogeneity measure. The watermark signal can be recovered without the host image. For applying integer to integer wavelet transform, the algonthem avoid the error in the quantity processing of traditional wavelet transform and works fast. Experiment results show the superior performance in both qualities of the resultant watermarked image and robustness of the embedded watermark signal against common signal processing such as noise adding, cutting and JPEG compression scheme. etc.