基于MTF识别的大气模糊图象复原(英文)

RSTORATION OF IMAGES BLURRED BY THE ATMOSPHERE,BASED ON MEAN MTF IDENTIFICATION

大气传递函数（ＭＴＦ），Ｈ，所引起的图象畸变可看作两个成分的贡献之和：一个确定成分＜Ｈ＞和一个随机成分△Ｈ而＜Ｈ＞又是大气扰动的平均ＭＴＦ和尘埃雾气微粒ＭＴＦ的和实际大气的Ｈ是完全未知的，要通过实验测量确定Ｄ．Ｓａｄｏｔ等人提出了一种改进的滤波器，其中以确定成分＜Ｈ＞作为滤波器的传函，而把△Ｈ作为噪音成分对待，但传函＜Ｈ＞的获取要依赖于实时实验测量显然，伴随ＰＳＦ实验测量的方法将难以履行某些应用场合（如卫星摄影测绘）的图象复原此外，经由该方法的复原结果已被表面噪音过重由于＜Ｈ＞的精确解析式已被Ｆｒｉｅｄ等人在总结前人研究的基础上给出，并被实验所证实，但解析式中的Ｆｒｉｅｄ参数ｒ０（表征能见度）仍然是未知的，依然要通过实验测量给出如果能从模糊图象本身中识别出参数ｒ０，则可解析求得平均扰动传函＜Ｈ＞所以关键是如何从识别ｒ０本文提出一种大气畸变图象复原的新方法该技术的先进性在于避开昂贵且费时的实验测量，而直接从模糊图象中识别＜Ｈ＞我们开发的这种识别是基于以下物理事实：１）＜Ｈ＞包含尘雾微粒ＭＴＦ和扰动ＭＴＦ的平均效果，它在秒级照相曝光时间内是确定不变的；２）模糊图象可由具有Ｇａｕｓ传函Ｈｇ的?

A new blind method of restoration of images distorted by atmosphere is presented in this paper.In imaging through the atmosphere,the system MTF can be decomposed into the sum of its mean <H>,and random component ΔH.The <H> have been studied by Fried 6 who derived analytical expressions.This technique deals with identification of Fried parameter r 0 in expression of <H>.The identification of r 0 is based on the facts:1)<H>,including average turbulence MTF and aerosol MTF,is determinate in a few second exposure times,and located at low frequency areas;2)A approximate restoration can be obtained by Wiener filter with Caussian H g;3)<H> has the same zero cross point as the H g and the image degraded by this <H>.It will be seen that a corrected r 0 can result in a good restoration result.This is due to the main contribution on blur is <H>,while the random MTF,ΔH,can be removed by Wiener filter.