Research Of Adaptive Robust Watermarking Algorithm For Digital Images On Transform Domain

With the coming of information era,the rapid development of computer network technology,multimedia information technology and related fields,digital products has been widely used and digital information becomes more and more important in modern life.Digital multimedia works are easy to store,copy and disseminate,which results in illegal copying and copyright theft and other information security issues increasing,as well as brings serious social problems.In ensuring the speed of information transmission at the same time,we also need to guarantee the security of personal information,trade secrets and intellectual property.In the field of copyright protection,digital watermarking plays an important role,which can hide the tags containing watermark information into multimedia digital works to protect their safety.However,the robustness and transparency of digital watermarking are contradictory to each other,under the premise of ensuring transparency,how to improve the robustness as far as possible is particularly critical.In order to solve the problem of copyright protection in traditional digital image watermarking and improve the security of digital works,an improved algorithm is proposed to balance the transparency and robustness of digital watermarking,as wells as enhance the ability of resisting various attacks.The main contents and innovative points of this paper are as follows:? The development background and research status of digital watermarking are systematically discussed,and the related basic knowledge is analyzed,as well as the related design method of image watermarking algorithm is studied,which provides a sufficient theoretical basis for the realization of this algorithm.? In order to improve the watermarking robustness and to solve the contradiction between the transparency and robustness of the watermarking,a digital image watermarking algorithm in wavelet domain based on singular value decomposition(SVD)and human visual system(HVS)is proposed.Firstly,the carrier image is decomposed by two level discrete wavelet transform(DWT),and its second level low frequency sub-band is divided into blocks.Then,each sub-block is carried on SVD,the modified cosine similarity measurement method is used to calculate the best watermarking embedding position according to HVS sensitivity to the average brightness.Finally,the encrypted watermarking is embedded into the selected singular values by the quantizing way,the embedding strength is adaptively adjusted according to singular value of the carrier image sub-block.The experimental results show that the transparency of the watermarking is very good,and it has high robustness against noise,filtering,cropping,JPEG compression and so on.? Aiming at the contradiction between invisibility and robustness in digital image watermarking,a digital image watermarking algorithm based on discrete cosine transform(DCT)and low density parity check(LDPC)code is proposed.Firstly,the binary watermarking image is processed by scrambling encryption and error correction encoding using Arnold transform and LDPC code.Next,the carrier image is divided into 88 ? blocks,and each sub-block is handled by discrete cosine transform.Finally,the values of selected middle frequency DCT coefficients are adaptively modified to embed the processed watermarking.The experimental results show that the security and transparency of the watermarking is good,which can also effectively resist the attack of filtering,JPEG compression,noise,rotation,cropping,translation,Gamma correction,histogram equalization and scaling,achieves the adaptive embedding and blind extraction of the watermarking as well.