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| 光学系统参数确定带宽约束的天文图像盲反卷积 | |
| 引用本文： | 罗林,樊敏,沈忙作.光学系统参数确定带宽约束的天文图像盲反卷积[J].天文学报,2007,48(3):374-382. |
| 作者姓名： | 罗林 樊敏 沈忙作 |
| 作者单位： | 1. 西南交通大学理学院,成都,610031;中国科学院光电技术研究所,成都,610209 2. 成都信息工程学院,成都,610041 3. 中国科学院光电技术研究所,成都,610209 |
| 基金项目： | 国家高技术研究发展计划(863计划);四川省应用基础研究计划 |
| 摘 要： | 大气湍流极大限制了地基大口径望远镜观测天文目标图像的空间分辨率.根据最大似然估计原理,提出了用实际光学带宽约束的可有效减小天文观测图像中大气湍流影响的盲反卷积方法,通过共轭梯度优化算法使卷积误差函数趋向最小.建立了望远镜光学系统参数和图像频域带宽的关系,采用变量正性约束、点扩散函数带宽有限约束,提高算法的收敛性.为避免图像处理中有效傅立叶变换频率超出截止频率,要求采集望远镜焦面图像时单个成像单元(如CCD像素单元)应小于四分之一衍射斑直径.算法中未用目标支持域约束,所提出的方法适用于全视场天文图像恢复.用计算机模拟和对实际天文目标双鱼座图像数据的恢复结果验证了所提出方法的有效性. |
| 关 键 词： | 望远镜 仪器 高角分辨率 技术 图像处理 |
| 修稿时间： | 2005-12-08 |
Blind Deconvolution of Astronomical Images with Band Limitation Determined by Optical System Parameters |
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| LUO Lin,FAN Min,SHEN Mang-zuo.Blind Deconvolution of Astronomical Images with Band Limitation Determined by Optical System Parameters[J].Acta Astronomica Sinica,2007,48(3):374-382. | |
| Authors: | LUO Lin FAN Min SHEN Mang-zuo |
| Institution: | 1 Science College, Southwest Jiaotong University, Chengdu 610031; 2 Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209; 3 Chengdu University of Information Technology, Chengdu 610041 |
| Abstract: | Atmospheric turbulence greatly limits the spatial resolution of astronomi- cal images acquired by the large ground-based telescope.The record image obtained from telescope was thought as a convolution result of the object function and the point spread function.The statistic relationship of the images measured data,the estimated object and point spread function was in accord with the Bayes conditional probability distribution,and the maximum-likelihood formulation was found.A blind deconvolution approach based on the maximum-likelihood estimation technique with real optical band limitation constraint is presented for removing the effect of atmospheric turbulence on this class images through the minimization of the convolution error function by use of the conjugation gradient opti- mization algorithm.As a result,the object function and the point spread function could be estimated from a few record images at the same time by the blind deconvolution algorithm. According to the principle of Fourier optics,the relationship between the telescope optical system parameters and the image band constraint in the frequency domain was formulated during the image processing transformation between the spatial domain and the frequency domain.The convergence of the algorithm was increased by use of having the estimated function variable(also is the object function and the point spread function)nonnegative and the point-spread function band limited.Avoiding Fourier transform frequency compo- nents beyond the cut off frequency lost during the image processing transformation when the size of the sampled image data,image spatial domain and frequency domain were the same respectively,the detector element(e.g.a pixels in the CCD)should be less than the quarter of the diffraction speckle diameter of the telescope for acquiring the images on the focal plane.The proposed method can easily be applied to the case of wide field-view turbulent-degraded images restoration because of no using the object support constraint in the algorithm.The performance validity of the method is examined by the computer simulation and the restoration of the real Alpha Psc astronomical image data.The results suggest that the blind deconvolution with the real optical band constraint can remove the effect of the atmospheric turbulence on the observed images and the spatial resolution of the object image can arrive at or exceed the diffraction-limited level. |
| Keywords: | Telescopes Instrumentation High Angular Resolution Techniques Image Processing |
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