Double Digital Watermark Research Based On Transformation Domain

Digital products have become the main means of information exchange, getting information from the Internet rises to an unprecedented depth and breadth, with the attendant illegal copying and tamper with such violations has been a topic of concern, copyright protection and the interests of the author is still a hot topic of the information security domain. As an important branch of information hiding, digital watermarking technology allows people to embedded particular significance labeling (Watermark) into digital products according to some digital watermarking algorithm under the premise of not affecting the quality of digital products, so as to achieve the goal of copyright protection content authentication.Spatial domain watermarking algorithm is relatively simple, the volume of data is relatively small, computing speed is usually faster, but the robustness of the information hidden is poor. And transforming domain watermarking algorithm, albeit complex, a large amount of data, however, the energy distribution of transforming domain focus, and determine the strength and robustness of the embedded watermark with the human visual system HVS model easily.Currently, the vast majority of digital watermarking algorithm is single in function. Or only solve the copyright issues of image, or only solve the problem of image content certification. Therefore, the study on robust, invisible double digital watermarking technology becomes the most popular and challenging direction, it has aroused great concern in the international community recent years.The study to the image digital watermarking algorithm is carried on in the paper, carrying on embedding and extraction of the digital watermark taking advantage of the wavelet transform to transforming domain, because wavelet transform signal or image can be unfolded on wavelet-level, a wavelet transform has functions of mathematical microscope ,such as zoom, deflation and shift, and may carry out more precise image mosaic, so it can image signal, as well as the nature of the image prior to the scheduled start dealing with the requirement of the series, and applied to the field of information hiding. At present the application is more image digital watermarking technology, which can improve the robustness of information hiding. the major work done and innovation spot by the following:Prime task of the article includes:First,static digital images as the study object is taken in the paper, on the basis of analyzing several typical digital watermarking algorithms about the space domain and transform domain, because the security is not high for LSB algorithm which is based on the spatial domain, so it is easy to cancel the information which hides in the lowliest place, proposes an improved digital watermarking algorithm based on wavelet transform. The method borrows ideas from the spatial domain algorithm LSB, and embedding the wavelet on image's the low-frequency band which is transformed for three levels, realizing adaptive embedded watermark image by changing the corresponding position's wavelet coefficients. Experiments show that the algorithm can resist the common attacks, it has very strong robustness.Second, analyzing principle of the singular value decomposition and the principle of wavelet transform deeply at all levels, as well as the impact to image processing and singular value decomposition wavelet analyzing, focus on single watermarking and double watermarking algorithm based on the discrete wavelet transform. Proposing a digital algorithm which modifying wavelet coefficients and singular value in sub-band of the wavelet domain combining spatial domain algorithm's idea and analysis of multi-resolution image pairs singular value of the map. The algorithm is based on the singular value decomposition and discrete wavelet transforming, carrying on the wavelet transforming to the original image, the SVD thinking is applied to coefficient matrix of the wavelet transform, and realizing embedding of gray image.Experimental results show that the algorithm has good anti-noise and anti-compression effect. Finally, on the basis of studying single digital watermarking, proposes a double digital algorithm based on SVD and DWT. The algorithm carries on dividing block according to the algorithm image texture features, first makes the first invisible watermark embedded in the original image of the low frequency domain in order to protect copyright image, and then embeds the second invisible watermark image to the intermediate frequency domain in order to authenticate image. The experiments show that the double digital water- marking system reaches the goal of copyright and content protection.Innovation spot of the article is:1. Proposes one kind of double digital watermark algorithm based on SVD and the DWT , this algorithm is one kind of robust double digital watermark algorithm, it may be applied in the field of realizing the copyright protection and the content authentication simultaneously. The algorithm embeds two invisible watermarks in the original image, embeds one invisible watermark to the low frequency domain in order to protect copyright image, embeds the other invisible watermark image to the intermediate frequency domain in order to authenticate image, it plays the role of dual protection.2. Proposes one kind of improved double digital watermark algorithm based on SVD and the DWT in view of the privacy communication, this algorithm has already realized the disorderly extraction, may realize the transmission of different duty or the confidential report in the field of military. This algorithm hides different information in image's different position using two key Key1 and Key2 in order to realize the privacy communication, the person who has the key may extract corresponding watermark information or accept different duty according to their key. It does not affect other people's information extraction or the duty acception so as to realize privacy communication.Although digital watermarking technology's application is still in the initial stage at home and abroad, establishment of the watermark company makes the watermark technology become practical and commercial, it will promote watermarking technology's vigorous development at home and abroad.