An improved preprocessed Yaroslavsky filter（IPYF）is proposed to avoid the nick effects and obtain a better denoising result when the noise variance is unknown.Different from its predecessors,the similarity between t...An improved preprocessed Yaroslavsky filter（IPYF）is proposed to avoid the nick effects and obtain a better denoising result when the noise variance is unknown.Different from its predecessors,the similarity between two pixels is calculated by shearlet features.The feature vector consists of initial denoised results by the non-subsampled shearlet transform hard thresholding（NSST-HT）and NSST coefficients,which can help allocate the averaging weights more reasonably.With the correct estimated noise variance,the NSST-HT can provide good denoised results as the initial estimation and high-frequency coefficients contribute large weights to preserve textures.In case of the incorrect estimated noise variance,the low-frequency coefficients will mitigate the nick effect in cartoon regions greatly,making the IPYF more robust than the original PYF.Detailed experimental results show that the IPYF is a very competitive method based on a comprehensive consideration involving peak signal to noise ratio（PSNR）,computing time,visual quality and method noise.展开更多
A novel scheme for photonic envelope detection and fiber transmission of 24 GHz impulse radio ultra-wideband(IRUWB) signal is proposed based on phase modulator(PM). In the system, an optics assisted envelope detection...A novel scheme for photonic envelope detection and fiber transmission of 24 GHz impulse radio ultra-wideband(IRUWB) signal is proposed based on phase modulator(PM). In the system, an optics assisted envelope detection unit(OAEDU) is used for filtering one of the first sidebands at the output of PM, then this narrow band optical signal transfers over single-mode fiber(SMF), and the envelope of 24 GHz IR-UWB signal is obtained after photodetection(PD) and low pass filter(LPF). The numerical simulation results show that the combination of PM and OAEDU can alleviate the fiber chromatic dispersion(CD) effectively. The proposed system may provide a simple and cost-effective solution for IR-UWB receiver.展开更多
基金Supported by Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University)(PL N1303)Open Fund of State Key Laboratory of Marine Geology(Tongji University)(MGK1412)+1 种基金Fundation of Graduate Innovation Center in NUAA(kfjj201430)the Fundamental Research Funds for the Central Universities
文摘An improved preprocessed Yaroslavsky filter（IPYF）is proposed to avoid the nick effects and obtain a better denoising result when the noise variance is unknown.Different from its predecessors,the similarity between two pixels is calculated by shearlet features.The feature vector consists of initial denoised results by the non-subsampled shearlet transform hard thresholding（NSST-HT）and NSST coefficients,which can help allocate the averaging weights more reasonably.With the correct estimated noise variance,the NSST-HT can provide good denoised results as the initial estimation and high-frequency coefficients contribute large weights to preserve textures.In case of the incorrect estimated noise variance,the low-frequency coefficients will mitigate the nick effect in cartoon regions greatly,making the IPYF more robust than the original PYF.Detailed experimental results show that the IPYF is a very competitive method based on a comprehensive consideration involving peak signal to noise ratio（PSNR）,computing time,visual quality and method noise.
基金supported by the National High Technology Research and Development Program of China(Nos.2013AA013303,2013AA013301 and 2013AA013403)
文摘A novel scheme for photonic envelope detection and fiber transmission of 24 GHz impulse radio ultra-wideband(IRUWB) signal is proposed based on phase modulator(PM). In the system, an optics assisted envelope detection unit(OAEDU) is used for filtering one of the first sidebands at the output of PM, then this narrow band optical signal transfers over single-mode fiber(SMF), and the envelope of 24 GHz IR-UWB signal is obtained after photodetection(PD) and low pass filter(LPF). The numerical simulation results show that the combination of PM and OAEDU can alleviate the fiber chromatic dispersion(CD) effectively. The proposed system may provide a simple and cost-effective solution for IR-UWB receiver.
