| As there is an urgent need for high-resolution remote sensing images,TDI(Time Delay and Integration)CCD(Charge-coupled Device)is widely used in the satellite sensors because it does not increase the carrying load but also improve the resolution of the remote sensing spacecraft?The working premise of TDICCD is to keep the consistency of the photo generated charge packet transfer and the focal plane of the object's motion,otherwise it will lead to a decline in image quality.During the satellite orbit,sports on moving parts cause the camera lens to shake,resulting in serious degradation of the image quality.Therefore,the study of the influence of flutter on the imaging quality of high-resolution remote sensing satellite images and the image restoration is a very significant research work.The main work of this paper is as follows:(1)Based on the working principle of TDICCD,a simulation model of TDICCD imaging with high speed camera is proposed.(2)Using ground electric triaxial vibration table,select the appropriate excitation parameters and establish the flutter environment.Under the action of an excitation source,vibration table vibratesin the X axis(satellite flight direction)and Y axis(perpendicular to satellite flight direction).Simulation images with different frequency,amplitude and exposure time are obtained by changing the parameters.Using high speed image analysis software PFA(FASTCAM Analysis Photron),we can get the offset and speed of each image.(3)Then the effect of flutter on the TDICCD imaging quality is analyzed.Through the simulation model,the effects of amplitude,frequency,exposure time and integral series on the TDICCD imaging quality are analyzed respectively under the random wave and the sine wave.(4)Achieve the recovery of image quality,compare the effect before and after correction and evaluated the image quality of the image before and after correction.At first,the image is corrected by using the offset of the simulation image of each level.Then superpose the simulation image of each level of integration to achieve the restoration of image quality.The correction effects of single axis sine wave,double axis sine wave,single axis random wave and double axis random wave are compared,and image quality evaluation was carried out.The conclusion drawn from the above work:(1)The effect of amplitude on image quality is the biggest.The larger the amplitude,the more blurred image.(2)If the integral time is greater than the vibration period,the effect of the vibration frequency on the image quality is very small;If the integration time is less than the vibration period,when the initial phase is the same,the shorter the vibration period,the more blurred image.(3)When the exposure time is less than the vibration period,the longer the exposure time,the more blurred the single stage simulation image.(4)When the integration time is greater than the vibration period,the increase of the integral series will not change the fuzzy degree of the image;when the integral time is less than the vibration period,the increase of the integral series will aggravate the fuzzy degree of the image.(5)Because the random wave is made up of a plurality of sine waves of different frequencies and amplitudes,so the impact of amplitude and frequency on the image quality is the same as the sine wave.(6)The images of PSNR(Peak Signal to Noise Ratio),SSIM(Structural SIMilarity)and VIF(Visual Information Fidelity)have improved significantly after correcting the images of the above four kinds of vibration wave.It shows that the image restoration method in the paper is applicable to the image under different vibration wave,and has better correction effect.This shows that it is feasible to restore the image quality based on the similarity of instantaneous field of view energy signal.It provides the basis for building the image compensation or restoration model for the state of the motion platform and the characteristics of the imaging system. |
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