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题名:
大气湍流退化扩展目标的高分辨成像研究
作者: 罗林
学位类别: 博士
答辩日期: 2006-09-07
授予单位: 中国科学院光电技术研究所
授予地点: 光电技术研究所
导师: 沈忙作
关键词: 盲反卷积 ; 斑点成像 ; 大气湍流 ; 图像恢复
其他题名: Study of blind deconvolution high resolution imaging for extended object degraded by atmospheric turbulence
学位专业: 光学工程
中文摘要: 地基大孔径光学系统观察天体目标,大气湍流、光子噪声和光学系统像差等因素严重降低了观察图像的分辨率。斑点成像和图象盲反卷积是提高天体目标图像分辨率的有效手段,本文着重研究了利用少数帧目标记录图像,在缺乏目标其他信息条件下,对扩展目标的高分辨成像方法。 根据最大似然估计原理,建立了天体目标成像所满足的最大似然估计关系,分别提出了严格约束的期望最大化和梯度优化的最大似然估计图像盲反卷积算法。通过减少函数值计算量,建立了快速的单变量搜索算法,并结合最速下降法和共轭梯度法的特点,建立了改进的图像盲反卷积混合梯度优化算法。 深入研究了约束条件对图像盲反卷积算法收敛性的影响,其中变量非负、能量守恒、带宽有限和多帧图像等约束是保证盲反卷积收敛的重要条件。提出了用光学系统参数确定带宽有限约束的方法,有效避免了无效解和图像的伪信息。为减少光子噪声,提出了低通平滑滤波抑制光子噪声,有效地提高了盲反卷积对低信噪比目标图像的恢复能力。利用斑点成像恢复目标相位的方法,作为盲反卷积算法的约束条件,建立了斑点成像和盲反卷积的混合处理算法,使算法的收敛性得到进一步提高。 理论上分析了图像盲反卷积的超分辨特性,通过实验证明了图像盲反卷积可以恢复出超过光学系统衍射极限以外的目标频率信息。研究了斑点成像和图像盲反卷积恢复光学像差目标图像的能力,实验验证了在一定可控制的随机扰动下,斑点成像和图像盲反卷积可以消除目标图像的光学像差。 进行了计算机模拟图像、实验室和天文台图像的实验,实验结果表明,论文提出和建立的天体目标图像高分辨成像算法,可以有效克服大气湍流、光子噪声和光学系统像差,提高目标图像的分辨率,其恢复图像的分辨率达到接近和超过光学衍射极限水平。
英文摘要: The resolution power of the ground-based telescope is severity decreased by the factor such as atmospheric turbulence, photon noise and optical system aberrations. The several effective approaches called the speckle imaging and image blind deconvolution can improve the observed images equality. In this paper, the method of high resolution image restoration with only several observed space extended object data and no other information about truth object is examined. Based on the maximum-likelihood approach, a strict constraint image blind deconvolution algorithm, which using expectation-maximization and gradient optimization method, is presented. By reducing the computation of optimized objective function and combined with the advantage of gradient-descent and conjugate-gradient techniques, an effective hybrid gradient method for image blind deconvolution is proposed. The convergence of image blind deconvolution is mainly influenced by the constraints such as positivity, total energy conservation and band-limited. The method of determining band limitation of the point-spread function with the optical imaging system parameters is newly stated and avoids trivial solution and image artifact. A novel method,which used to reducing photon noise, edge effects and ringing of restoration images,is developed and increasing capacity of restoring the low signal-noise rates images. The phase constrained of blind deconvolution algorithm is formed by using speckle imaging method to reconstruct object phase from a few short-exposure images and speed convergence of image blind deconvolution. The super-resolution of image blind deconvolution is proved by theoretic analysis and simulation experiments. Experiment results suggest that the frequency of restoration images is beyond out the diffraction-limited. The capacity of removing optical aberration of image blind deconvolution is examined. The speckle imaging and image blind deconvolution method can remove optical aberrations by the controlled random wave front disturbance. A series restoration results of simulation data, laboratory and real astronomical data show that proposed method of high resolution image restoration is validity for overcoming effects of atmospheric turbulence, photon noise and instrument-induced aberrations, and improving the resolution of real observed astronomical images, and partly removing the diffraction effect of optical system on restoration images.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/157
Appears in Collections:光电技术研究所博硕士论文_学位论文

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Recommended Citation:
罗林. 大气湍流退化扩展目标的高分辨成像研究[D]. 光电技术研究所. 中国科学院光电技术研究所. 2006.
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