Research On QR Code Watermarking Technology Based On DWT-SVD

In the information age,image as an intuitive multimedia information bearing way plays a very important role in people's communication.However,illegal access and use of image has become very common accompany with the rapid development of the internet.Digital watermarking technology can be used to embed information which is needed to hide into multimedia files such as images.The hidden information also can be extracted accurately by the corresponding watermarking algorithm while needed which plays an important role in copyright authentication.QR code is a widely used information coding method which has high fault tolerance and anti-fouling ability,and the decoded information is accurate which can indirectly improve the robustness of digital watermarking algorithm.In this thesis,we research the watermarking algorithms combine gray QR code and color QR code with the carrier image respectively,and the concrete work as follows:Firstly,an improved watermarking algorithm for anti-geometric attacks based on DWT-SVD is proposed.The algorithm utilities the feature of singular value decomposition,that is,only a small number of singular values can represent most of the signal energy and also has a strong ability of anti-noise.In algorithm twice singular value decompositions(SVD)are carried out.For the first time,the data matrix of the watermark and the carrier image are decomposed respectively,and the eigenvalues of watermark are embedded into the second half part of carrier eigenvalue matrix to get a new synthetic matrix.Then decompose the synthetic matrix and take out the singular value matrix to replace that of the carrier image.It is proved that the above operation can improve the transparency of watermark.Through a variety of attack experiments,the algorithm is proved to have good transparency and robustness.Secondly,a watermark algorithm based on color QR code is also proposed in this thesis.In this algorithm,color QR code is embedded into one of the channels of the carrier image's RGB channel.According to the characteristics of color QR code,a scheme of pre-processing of color QR code is proposed.In the process of preprocessing,the discrete wavelet transform technique is used to compress QR code,and different wavelet coefficients are reserved for different color channels of QR code.Finally,combine all the reserved wavelet coefficients to obtain the new watermark image.After preprocess the main features of the original color QR code is combined into one image which solved the problem of the original color QR code's capacity.The simulation results show that the color QR code which extracted from the watermarked images with many kinds of attack can not only be correctly decoded,but also the extracted color QR code are basically the same with original color QR code which proved this algorithm has strong robustness to these attacks.