| With the rapid development of aerospace industry,small satellite has set off a new commercial wave due to its advantages in light weight,low cost and wide range of applications.Due to the limitation of small satellite in both weight and volume,it puts forward higher requirements.How to design an imaging system with smaller volume and weight and higher resolution has become a focus in the field of small satellites.The resolution of the imaging system mainly depends on the aperture of the main lens(mirror).From the perspective of optical system design,it is a popular idea to design the optical imaging system as a folded shape.However,this kind of folding will inevitably lead to special shaped lens(mirror),which will certainly bring new influence on the clarity of the acquired image.In this paper,the technical route and approach of image restoration for the folded lens(mirror)imaging system are studiedFirstly,based on the related knowledge of image restoration and the causes of image degradation,this paper studied the non constraint,constraint class,maximum entropy,blind restoration and other restoration methods of image restoration.On the basis of programming,it carries out the simulation image blur experiment,realized the convolution blur and motion image blur of image,and gave the programming ideas of inverse filter and Wiener filter.The blurred image was restored,and the image restoration effect under different algorithms was studied.Secondly,this paper studied the common noise in the process of satellite image acquisition,including the types of noise,the causes of noise,the noise distribution function and so on.Through the computer simulation experiment of common noise,the situation of image polluted by noise was simulated.On this basis,the image denoising technology was studied,and the denoising effect of the existing denoising technique was simulated and compared.At the same time,the evaluation algorithm of image restoration quality was studied,which was used to evaluate the quality of image restoration and denoising.Finally,based on the analysis of optical imaging system of folding satellite,the concept of heteromorphic imaging system was proposed.A satellite imaging system in cross shape was proposed in this paper.The special point spread function(PSF)of the cross-shape imaging system was estimated,and how to obtain a high resolution image of the cross-shape imaging system was discussed.Through numerical simulation and calculation,it was verified that the processing effect of the image with near ideal definition could be obtained by the inverse filtering method,which was implemented by considering the ideal PSF of the cross-shape imaging system.In the case of suffering a noise,this paper proposed a PSF correction method to carried out the image inverse filtering restoration.The key point was that the PSF of inverse filtering was the product of the image PSF with a correction coefficient.So the optimization on the correction coefficient was required in order to obtain a satisfied restoration effect. |
