Research On Image Reconstruction Method Of Sparse Aperture Imaging Systems

Sparse-aperture imaging technology uses multiple small-aperture telescopes arranged into a certain form of sparse-aperture array to achieve the equivalent imaging effect of large-aperture telescopes.It is currently one of the effective methods to realize large-aperture remote sensing systems.Because the sparse aperture system is a partial filling of its equivalent large aperture,the light-passing area is reduced,resulting in a reduction in the contrast of the image,and a serious drop in the middle and low frequencies.In order to obtain a better image,image reconstruction is essential.This article mainly focuses on the image reconstruction of sparse aperture system,including the following aspects:Firstly,the basic imaging principle of the sparse aperture imaging system is studied,the imaging model of the sparse aperture system is constructed,and the differences between different types of sparse aperture systems are compared and analyzed.The influence of characteristic indexes such as aperture structure,equivalent aperture and fill factor on the imaging quality of sparse aperture is analyzed.The typical pupil arrangement of the sparse aperture imaging system is simulated,and the characteristics of the PSF and MTF of the system under the typical pupil arrangement are compared and analyzed.Secondly,the sparse aperture system image reconstruction is simulated.The degradation model of the sparse aperture system is established,the degraded image obtained by the simulation is preprocessed,and the appropriate filter is selected to denoise.Then,Wiener filtering,Richardson-Lucy,constrained least squares and algorithms based on Laplacian operator and parametric Wiener filtering are used to perform theoretical image restoration on sparse aperture images of various array structures.The simulation results are evaluated subjectively and objectively.Through the simulation results,we know that the algorithm based on Laplacian operator and parameter Wiener filtering used in this paper has a certain reconstruction effect for sparse aperture images of various array structures,and can effectively improve the definition.And the signal-to-noise ratio,and improve the low-frequency information in the image.Finally,an optical sparse aperture imaging experiment was designed and built,and an Circle-7 sparse aperture system was used for imaging experiments.The experiment first measured the point spread function of the system,and then shot three sets of experimental images,namely the national standard N3 discrimination rate board,the dynamic target UAV,and the static target tower crane.Using the algorithm based on Laplacian operator and parameter Wiener filter used in this paper,the three sets of target images are reconstructed,and the reconstruction results are evaluated by subjective and objective evaluation indicators.It is verified that the algorithm in this paper has a good reconstruction effect on the image formed by the actual sparse aperture imaging system.