When estimating a sharp image from a blurred one, blur kernel noise often leads to inaccurate recovery. We develop an effective method to estimate a blur kernel which is able to remove kernel noise and prevent the production of an overly sparse kernel. Our method is based on an iterative framework which alternatingly recovers the sharp image and estimates the blur kernel. In the image recovery step, we utilize the total variation (TV) regularization to recover latent images. In solving TV regularization, we propose a new criterion which adaptively terminates the iterations before convergence. While improving the efficiency, the quality of the final results is not degraded. In the kernel estimation step, we develop a metric to measure the usefulness of image edges, by which we can reduce the ambiguity of kernel estimation caused by small-scale edges. We also propose a hybrid ℓp norm, which is composed of ℓ2 norm and ℓp norm with 0.7≤p<1, to construct a sparsity constraint. Using the hybrid ℓp norm, we reduce a wider range of kernel noise and recover a more accurate blur kernel. The experiments show that the proposed method achieves promising results on both synthetic and real images.
Constraint-based wavelength routing comes with the cost of higher blocking probability to provide Quality of Service (QoS) guarantee in Service-guaranteed optical networks; thus a load balancing method is presented in this paper to improve the performance of constraint-based wavelength routing. Also the Modified Backward-Forward heuristic (MBFH) is proposed, which can be utilized to select an optimal lightpath with one constraint. Simulation results show that with the application of load balancing method, constraint-based wavelength routing based on the MBFH can achieve better performances in terms of blocking probability and resource utilization ability.
The Information Optoelectronic Technology Research Institute (IOTRI) in Tsinghua University brings together research activities and research projects in various optoelectronic devices, integrated photonic devices, optical fiber telecommunication and networks, optical display, optical storage and optical fiber sensing systems. The researches on the optical components for the all optical networks are executed in the area of Fiber Bragg Grating, Wavelength Converters, Tunable filters, Fiber Amplifiers, DFB+EA integrated light source chips and modules, optical nonlinear macromolecule material and its application, Fiber Amplifiers, etc. and the forecast researches on photonic crystal and nanophotonics are also started. Up to now, about 10 research projects on optical component for all optical networks are kept on going in IOTRI with the projects supports by the government through the National High-tech R&D Program ("863" program), the National Fundamental Research and Development Program (“973” Program), the National Natural Science Foundation (NSFC), Tsinghua 985 Project, Foundation project of Tsinghua University, and some cooperated projects. All these projects cover the following research areas: Fiber Bragg Grating and its application in DWDM systems such as broadband dispersion and dispersion slope compensation, polymer optical waveguide and its applications, photonic crystal's theoretical analysis and design, wide-band dynamic gain equalized FRA+EDFA hybrid module and related components, wavelength converters and its application in optical networks, tunable PMD compensators, Fiber optical parametric amplification, Gain Coupling in high-speed integrated light sources, etc. Some projects are just carried on, and some of them achieved a lot. About 30 papers in the above areas are posted in the last 3 years.