The Research Of Image Filtering With Multidirectional Wavelet Transform And Conditional Access System In DTV

This thesis deals with two projects, which are " Image Filtering with Wavelet Transform" and "Conditional Access System and Set Top Box Integration in DTV". The thesis is divided into two parts to study the problems in two projects .Part 1 studies the problems of image filtering with multidirectional wavelet transform. From two different scopes of wavelet transform, three image filters are presented in this part.First, an image filter, which is "Spatially Multidirectional Selectivity with Neighborhood Characteristics Filter (MSNC)" is presented. MSNC Filter substitutes the multidirectional selective filter for horizontal-vertical selective filter in Spatially Selective Filter (SS) to select the multidirectional edges of image. Then further step to restrain noise in minimum wavelet scale is processed according to Neighborhood Characteristics. By different processing with edges and noise the algorithm can efficiently protect image edges and restrain Gaussian noise.Second, image filtering with new downsampling lattice are present. With introducing Directional Wavelet, the method brings out a new downsampling lattice. With the new lattice, images can be decomposed in 45 and 135 degree with multiscale separable directional wavelet transform. On this basis, two image filters are presented, which are "Diagonal Direction Wavelet Transform (DDWT)" and "Four Direction Wavelet Transform (FDWT)". For the new lattice is more reasonable, the effect of these two method are both better than the standard separable 2-D wavelet filtering.Part 2 studies the process of integration of conditional access system with set top box of Fujitsu's SmartMPEG. Firstly, the scrambling part in program transmission end and the descrambling part in set top box and smartcard are introduced. DVB simulcrypt and multicrypt technique are also introduced. Secondly, the hardware platform and software structure of SmartMPEG and operation system Necleus are interpreted. Then ca-core and the process of integrating ca software, receiving B-mail and watching IPPV with set top box are illuminated. Finally, the software implementation of ca driver and ca-core' s correspondence and the process of obtaining ECM and EMM' s PID are discussed in detail.