An adaptive algorithm operating in the Contourlet domain is presented. Contourlet is a new image sparse representation, which is better than a wavelet for piecewise smooth images with smooth contours. Because of flexi...An adaptive algorithm operating in the Contourlet domain is presented. Contourlet is a new image sparse representation, which is better than a wavelet for piecewise smooth images with smooth contours. Because of flexible multiresolution, local and directional sensitivity of Contourlet transform, our approach also defines significant-tree in the Contourlet domain. By analyzing the relation of the Contourlet coefficients, we embed the watermarking into all the coefficients of each significant-tree. Then referring to the statistical properties of the coefficients, the masking characteristics of texture are defined for adaptively controlling the embedding strength. Experimental results show that the proposed algorithm is highly robust to various attacks, such as JPEG compression, medium filtering, cropping and rotation. Furthermore, comparisons with a classical method in the wavelet domain prove the validity of the new algorithm.展开更多
An algorithm using fixed-lag smooth filtering to improve the precision of EIS algorithm is presented in this paper. Ftrstly, gray projection algorithm （GPA） is used to calculate the interframe global motion vectors....An algorithm using fixed-lag smooth filtering to improve the precision of EIS algorithm is presented in this paper. Ftrstly, gray projection algorithm （GPA） is used to calculate the interframe global motion vectors. Secondly, the fixed-lag smooth filter is used to smoothen the motion track of the original video sequence, according to different motion models. At last, the original sequence is compensated by using the compensation vectors calculated from filtering. This algorithm has been proved superior in filtering precision by experiments of video sequences in different motion scenes. This algorithm also satisfies the real-time request.展开更多
We study theoretically transport properties of two-dimenslonal electron gases through antiparallel magneticelectric barrier structures. Two kinds of magnetic barrier configurations are employed： one is that the stren...We study theoretically transport properties of two-dimenslonal electron gases through antiparallel magneticelectric barrier structures. Two kinds of magnetic barrier configurations are employed： one is that the strength of the double δ-functlon in opposite directions is equal and the other is that the strength is unequal Similarities and differences of electronic transports are presented. It is found that the transmission and the conductance depend strongly on the shape of the magnetic barrier and the height of the electric harrier. The results indicate that this system does not possess any spin filtering and spin polarization and electron gases can realize perfect resonant tunneling and wave-vector filtering properties. Moreover, the strength of the effect of the inhomogeneous magnetic field on the transport properties is discussed.展开更多
基金the National High Technology Research and Development Program of China(No.2003AA148040)the National Natural Science Foundation of China(No.10471151,60216263,6990312)
文摘An adaptive algorithm operating in the Contourlet domain is presented. Contourlet is a new image sparse representation, which is better than a wavelet for piecewise smooth images with smooth contours. Because of flexible multiresolution, local and directional sensitivity of Contourlet transform, our approach also defines significant-tree in the Contourlet domain. By analyzing the relation of the Contourlet coefficients, we embed the watermarking into all the coefficients of each significant-tree. Then referring to the statistical properties of the coefficients, the masking characteristics of texture are defined for adaptively controlling the embedding strength. Experimental results show that the proposed algorithm is highly robust to various attacks, such as JPEG compression, medium filtering, cropping and rotation. Furthermore, comparisons with a classical method in the wavelet domain prove the validity of the new algorithm.
文摘An algorithm using fixed-lag smooth filtering to improve the precision of EIS algorithm is presented in this paper. Ftrstly, gray projection algorithm （GPA） is used to calculate the interframe global motion vectors. Secondly, the fixed-lag smooth filter is used to smoothen the motion track of the original video sequence, according to different motion models. At last, the original sequence is compensated by using the compensation vectors calculated from filtering. This algorithm has been proved superior in filtering precision by experiments of video sequences in different motion scenes. This algorithm also satisfies the real-time request.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 19847004 and 10474025.
文摘We study theoretically transport properties of two-dimenslonal electron gases through antiparallel magneticelectric barrier structures. Two kinds of magnetic barrier configurations are employed： one is that the strength of the double δ-functlon in opposite directions is equal and the other is that the strength is unequal Similarities and differences of electronic transports are presented. It is found that the transmission and the conductance depend strongly on the shape of the magnetic barrier and the height of the electric harrier. The results indicate that this system does not possess any spin filtering and spin polarization and electron gases can realize perfect resonant tunneling and wave-vector filtering properties. Moreover, the strength of the effect of the inhomogeneous magnetic field on the transport properties is discussed.
