Research On Blind Detection Of Digital Watermarking Still Image

The technology of blind detection on the digital watermarking of still image needs to work without any necessary information, such as the original carrier information, watermarks information, schemes and key of embedding or extraction etc. The technology is usually used to detect existence of watermarks or some watermarks information. The dissertation proposed some blind detection schemes aiming at different type watermarking. Detailed analysis on properties and computer simulations are given for every scheme. The main topics of this dissertation are as the follows:Firstly, two algorihms of blind detection on LSB (Least Significant Bit) digital watermarking of still image are proposed. With the aid of image engineering, one algorithm based on statistic property uses the Laplace value of the pixel and other pixels around it to deduce length formula of watermarks in the test image. The algorithm has good detection results on both concentrated and dispersed watermarking information. It also could keep high detection probability at low embedding rate. The algorithm based on image segmentation utilizes the locality property of actual watermarking to segment the test images. It studies the distribution of node degree in MSTs. It carries out blind detection on digital watermarking according to Fisher principle. The algorithm has good detection results on the information both of replacement embedding and matching embedding.Secondly, the algorithm of blind detection on DCT (Discrete Cosine Transformation) digital watermarking of still image is proposed. By energy of noise, the stochastic resonance system is utilized to increase amplitude of watermarking information greatly. As a result, the difference between stego watermarking information and original information increases. Based on SVM algorithm, the blind detection is carried out on two general DCT watermark embedding methods which are concentrative embedding algorithm and dispersed embedding algorithm. Simulation results show high detection probability at low embedding strength.Thirdly, the algorithm of blind detection on DWT (Discrete Wavelet Transform) digital watermarking of still image is proposed. The algorithm utilizes KFDA (Kernel Fisher Discrimination Analysis) theory. With the help of research results of blind detection on DCT digital watermarking, the algorithm passes the test information by stochastic resonance system so as to amplify weak signals. Then the algorithm chooses suitable sample vector by computation. KFDA theory which is a kind of learning machine with high precision is used to realize blind detection. Both theoretical analysis and simulation results show that the algorithm improves detection probability at low embedding strength. At the same time the algorithm also decreases false alarm rate.Finally, algorithms of transmitter identification (TxID) method for DVB-H(Digital Video Broadcasting-Handheld) system are proposed. They are both based on digital watermarking technology. The spatial embedding algorithm embeds digital watermarking signals in the time domain of DVB-H transmitter. Receiver identifies the transmitter by detecting the embedded information. The algorithm is easy to be realized. The performance of BER shows that the distortion induced by digital watermarking information can be ignored. While the frequency embedding algorithm signals are embedded in the frequency domain of transmitter. Receiver identifies the transmitter by detecting the embedded information with the method of iteration and feedback. Compared with the spatial embedding algorithm, the frequency one improves dependence on system. According the theory of watermarking, two algorithms proposed can detect watermarking information even in wireless environment with low embedding rate. And the algorithms can improve PRPA of transmitter in some way. Although extral information is embedded, utilization rate of frequency spectrum is unchanged.