共查询到17条相似文献，搜索用时 156 毫秒
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本文以ＣＣＤ图象为技术背景，指出ＣＣＤ图象噪声主要将以与信号有关的泊松噪声形式存在。根据图象形成的模型及图象统计特性，提出了最大似然法，最大后验概率法及最大复原方法，针对ＭＡＰ法提出了具体算法和参数估计方法，并提出应用图象分割法来提高计算机复原速度，节省存储空间。 相似文献
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本文详细地介绍了利用二维离散付里叶变换(DFT)进行图象复原的方法。文中给出了一种利用频谱拟合来准确地求得系统的光学传递函数的方法。在云台CCD系统上进行实际试验的结果表明将系统的空间分辨率提高了2.75倍,将原来连在一起的双星明显地分开了。最后,文章还对DFT图象复原的优缺点进行了讨论。 相似文献
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在简要介绍了由Hofmann等提出的迭代最小二乘法天文像复原法砌砖法(Building
block)的原理后，提出用斑点干涉术等方法对被观测目标像的范围大小进行大概估计的预处理方案，这样将做到对砖块的区域限定投放，避免大量无效的砖块投放迭代步骤。天文高分辨率像复原实验表明，砌砖法的效率被大大地提高了。 相似文献
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在简要介绍了由Hofmann等提出的迭代最小二乘法天文像复原法：砌砖法（Building block)的原理后，提出用斑点干涉术等方法对被观测目标像的范围大小进行大概估计的预处理方案，这样将做到对砖块的区域限定投放，避免大量无效的砖块投放迭代步骤，天文高分辨率像复原实验表明，砌砖法的效率被大大地提高了。 相似文献
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We have developed a new Bayesian image reconstruction method that has been shown to be superior to the best implementations of other methods, including Goodnessof-Fit (e.g. Least-Squares and Lucy-Richardson) and Maximum Entropy (ME). Our new method is based on the concept of the pixon, the fundamental, indivisible unit of picture information. Use of the pixon concept provides an improved image model, resulting in an image prior which is superior to that of standard ME. 相似文献
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A principle of restoration methods based on multichannel blind deconvolution (MBD) is introduced. The methods assume that
for every un-degraded unobservable image several degraded observed images are available. It is better conditioned than classical
single channel approach. The first algorithm represents a generalization of iterative deconvolution scheme introduced for
single images. The second MBD algorithm is based on so-called subspace technique. The subspace method is not iterative and
this possibly implies an implementation that can be computationally more efficient. Both methods are presented in applications
to artificial image data (computer-generated multichannel degraded data) with known ideal image to get a comparison with restored
one. Performance in a real situation on solar photosphere images is shown. 相似文献
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The effectiveness of equal power spectrum filtering in image restoration is analyzed via digital simulation. We start with a gray-scale map of concentric rings with different grey values. To obtain a dirty image, the original image is first transformed via a linear space-invariant system. Then, white noise is mixed into the image. The equal power spectrum filter is then used for the image restoration. The signal to noise ratio (SNR) and a defined steepness of the steps, together with the visual impression, are accepted to characterize the performance of the image restoration. It is concluded that a satisfactory restoration can be realized when the SNR > 15. When SNR < 5, the image is completely un-restorable. The effect of system's transfer function on image restoration is also discussed. The effectiveness of the presented model of equal power spectrum filter is confirmed by applying it to the restoration of an actual astronomical image. Finally, a typical application of the equal power spectrum filter is given. 相似文献
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利用计算机数值模拟的方法，对等功率谱滤波方法的图像恢复效果进行测定，原始清晰图像选用以（0，0）为圆心的台阶式灰度图，且台阶灰度值非常接近，这些清晰图像首先进行系统退化，然后加入噪声（本文选用白噪声）生成脏图，图像恢复采用等功率谱滤波器，并将信噪比简化为常数k，图像恢复效果的好坏，用恢复后图像的信噪经和台阶的陡度（台阶的下底宽减上底宽，单位为像素个数）来定量测量，并结合普通图像的恢复，进行定性的视觉观察，主要测量退化图像的信噪比对图像恢复效果的影响，结果是：当信噪比＞15：1，图像恢复效果较好，当信噪比小于该值时，图像恢复效果较差，当信噪比下降到5：1时，图像恢复效果极差，几乎无法辨认，其次是系统传递函H对图像恢复效果的影响，也进行了一些讨论，最后，通过对实际的天文图像进行恢复，验证了测量过程的合理性和结果的正确性，并列举了等功率谱波器的一个典型应用，即在同态滤波器中使用等功率谱滤波器的传递函数。 相似文献
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《天文和天体物理学研究(英文版)》2014,(8)
In order to implement an observing strategy,image degradation that occurs during optical observation of space debris is ineluctable and has distinct characteristics. Image restoration is presented as a way to remove the influence of degradation in CCD images of space debris,based on assumed PSF models with the same FWHM as images of the object. In the process of image restoration,the maximum entropy method is adopted. The results of reduction using observed raw CCD images indicate that the precision in estimating positions of objects is improved and the effects of degradation are reduced. Improving the astrometry of space debris using image restoration is effective and feasible. 相似文献
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《Chinese Astronomy and Astrophysics》2013,37(1):97-106
The CCD field of view of the Near Earth Object Survey Telescope (NEOST) is 1.94°xl.94°. As a wide-field telescope, the focusing based on a single star will lead to an uneven distribution of PSF (Point Spread Function) on the CCD image due to the field curvature. The features of the PSF distribution on the CCD image are studied. By fitting the relation between the defocusing and the FWHM (Full Width at Half Maximum) of PSF, the curved focal surface is simulated and therefore the best imaging plane is determined. Hereby, a focusing method based on the optimum imaging plane determined by judging the histogram of FWHM is proposed. 相似文献