移位相加法日间探测低信噪比恒星 -

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移位相加法日间探测低信噪比恒星

doi:10.3788/CO.20160904.0405

王昊京^1,,,
吴量^{1, 2},
王建立¹,
张世学¹,
杨轻云¹

1.
中国科学院长春光学精密机械与物理研究所, 吉林长春 130033
2.
中国科学院大学, 北京 100049

基金项目:

国防科技创新基金资助项目No.CXJJ-10-M53

详细信息

通讯作者:
王昊京(1983-),男,河南郑州人,助理研究员,2007年于吉林大学获得学士学位,2012年于中国科学院长春光学机密机械与物理研究所获博士学位,主要从事图像处理、辐射测量、导航等方面的研究。E-mail:wanghaojing@vip.qq.com

中图分类号:TP394.1;TH691.9
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- 被引次数:0
出版历程
- 收稿日期:2016-03-24
- 修回日期:2016-04-28
- 刊出日期:2016-08-01

Low SNR star detection by shift-and-add method in daytime

1.
Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
2.
University of Chinese Academy of Sciences, Beijing 100049, China

Funds:

National Defense Science and Technology Innovation Fund ProjectNo.CXJJ-10-M53

More Information

Corresponding author:E-mail:wanghaojing@vip.qq.com

摘要

摘要:为实现白天红外光电测量系统对低信噪比恒星的质心及能量高精度计算，本文给出一种高效的方法。首先，分析了红外光学系统白天恒星的成像特征。其次，先对采集的图像序列进行预处理操作得到预处理图像。接着对预处理图像序列执行叠加求均值和下采样操作得到下采样图像。在下采样图像中以亮度为特征求取恒星的疑似位置后，在预处理图像序列上建立与疑似位置相对应的目标区域，在目标区域内顺序求取质心序列。对目标区域的图像序列以质心偏移为基础进行移位相加后获取目标图像。在目标图像上以信噪比为判据完成恒星提取，以及质心和能量的计算。再次，分析指出此方法能增强目标信噪比的原理，并给出其适用范围以及相关参数的确定方法。最后通过实验表明，采用移位相加法可增强目标的信噪比，并提高提取正确率；且对于SNR不大于4.8的恒星可将其质心和能量计算精度平均提高0.06 pixel和28.5%。移位相加法对低信噪比的恒星可较为精确地计算其质心和能量。
- 低信噪比/
- 移位相加法/
- 图像叠加/
- 质心提取/
- 能量计算
Abstract:In order to accurately calculate star's centroid and energy in infrared electro-optical measuring system in daytime for low SNR star, an efficient method is presented. Firstly, according to the optical characteristics of electro-optical measuring system, the imaging characteristics of stars during the day are analyzed. Secondly, in order to obtain pre-processing sequence, these operations, which include non-uniformity correction, bad point's correction and background subtraction, are performed orderly in the acquired image sequence. Then a down-sampled image is got by performing image-stacking and down-sampling operation in the pre-processing sequence. Stellar suspected position is obtained by brightness characteristics in the down-sampled image, and a target area is located at stellar corresponding suspected position in the pre-processing sequence, then centroid sequence is extracted from the pre-processing sequence inside the target area. The sub images inside target area whose center is at the centroid are shifted and averaged to get a target sub image. Star extraction, centroid extraction and energy calculation are performed in the target image by stellar SNR criterion. Thirdly, the principle of this method to improve target SNR is revealed, its scope of application and the ways to determine the relevant parameters are analyzed. Experimental results indicate that the proposed shift-and-add method can improve target SNR and the extraction accuracy, for stars with SNR less than 4.8, its centroid extraction and energy calculation accuracy are increased by 0.06 pixel and 28.5% in average, respectively. Thus the shift-and-add method can achieve more accurate calculation of centroid and energy for low SNR star.
- low SNR/
- shift-and-add method/
- image-stacking/
- centroid extraction/
- energy calculation

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图 1目标和背景区域标记

Figure 1.Target and background regions′ notation

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图 2子图像SubI_i-1平移前后与子图SubI_i的位置关系

Figure 2.Position relationship between before and after translation

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图 3仿真生成的不同信噪比星点

Figure 3.Different SNR star points produced by simulation

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图 4移位相加法信噪比的提升倍数

Figure 4.SNR improvement by the shift-add method

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图 5移位相加法与原图上直接求取的SNR′的比值

Figure 5.SNR′ ration with the shift-add method and direct method which got SNR′ in a preprocessed image

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图 6移位相加法质心提高的数值

Figure 6.Centroid accuracy improved by shift-add method

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图 7移位相加法对能量误差比率减小的数值

Figure 7.Energy error ratio reduced by shift-add method

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图 8中波相机放置在1.23 m望远镜的轴头上

Figure 8.MIR camera placed in a 1.23 m telescope axis head

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表 1移位相加法的结果

Table 1.Results obtained with shift-add method

SNR	提取率(均值)/%	SNR′(均值)	质心误差PtErr(pixel)	能量误差比率EgErr/%
0.619	28	1.23	0.879	71.50
0.975	88	1.39	0.537	24.90
1.331	99	1.66	0.395	11.90
1.687	100	2.10	0.293	12.10
2.043	100	2.40	0.221	7.30
2.399	100	2.74	0.175	5.10
2.755	100	3.08	0.161	4.00
3.111	100	3.49	0.137	2.50
3.467	100	3.80	0.124	0.30
3.823	100	4.21	0.104	2.00
4.179	100	4.55	0.106	1.60
4.535	100	5.01	0.089	1.70
4.892	100	5.27	0.076	0.40

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表 2在预处理过的图像直接求取的结果

Table 2.Results acquired in the pre-processed images

SNR	提取率(均值)/%	SNR′(均值)	质心误差PtErr(pixel)	能量误差比率EgErr/%
0.619	2	1.07	0.971	148.29
0.975	9	1.12	0.664	72.25
1.331	11	1.07	0.523	64.98
1.687	38	1.15	0.369	48.19
2.043	69	1.21	0.295	33.29
2.399	91	1.28	0.254	28.93
2.755	100	1.42	0.201	26.01
3.111	100	1.57	0.162	20.44
3.467	100	1.78	0.150	18.53
3.823	100	1.85	0.122	15.15
4.179	100	2.00	0.113	15.07
4.535	100	2.13	0.103	13.39
4.892	100	2.20	0.089	10.78

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表 3白天移位相加法提取的信噪比结果

Table 3.SNR results of the shift-add method in daytime experiment

SNR′₂	提取率(均值)/%	SNR′₁	SNR′₁/SNR′₂
1.53	100	3.21	2.10
1.93	100	4.27	2.21
2.15	100	4.97	2.31
2.33	100	5.12	2.19

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表 4质心提取的对比实验结果

Table 4.Contrast experiment results of centroid extraction

SNR′₁	kμ₂/pixel	μ₁/pixel
3.21	0.157	0.193
4.27	0.112	0.123
4.97	0.094	0.110
5.12	0.081	0.970

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