The Research Of Digital Image Watermarking Technique Based On Wavelet Transform

With the development of multimedia technology and the popularity of Internet, the protection of the intellectual property rights has become increasingly important. Digital media offers several distinct advantages, such as high quality, easy editing, high fidelity copying. Digital information can be duplicated and distributed easily has led to the need for effective copyright protection tools. Digital watermarking which is one of the research focus in the academic world presents a candidate key to those questions.This paper has make some research on the digital image watermarking based on wavelet transform and proposed a digital watermarking algorithm combining the discrete wavelet transform(DWT) with singular value decomposition(SVD). The algorithm's main idea is that after the original image is decomposed with DWT and the low sub-band is decomposed by SVD, the gray image watermarking is embed into the singular value with adaptive intensity. It is well robust to the attack of image cropping and JPEG compression. By analyzing the quantization -based wavelet domain digital watermarking algorithms, a novel blind watermarking scheme with double watermarks in wavelet domain is presented in this paper. The double watermarks is embed into both low sub-band and high sub-band using the way of quantization-based wavelet domain. To enhance the invisible capability of the algorithm, considering the HVS characteristics of human eyes, the visible error thresholds are calculated for coefficients of HL and LH sub-bands to determine whether a coefficient is robust or not. By selecting the quantization factor adaptively, the algorithm's embedding capacity and robustness are enhanced. In the end, we introduced the digital image watermarking system—DIWS, which is based on the research of the digital watermarking algorithms in this paper.