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Open AccessArticle

Accurate and Rapid Auto-Focus Methods Based on Image Quality Assessment for Telescope Observation

1
School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
2
Laboratory of Imaging Detection and Intelligent Perception, University of Electronic Science and Technology of China, Chengdu 611731, China
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School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China
4
China air to Air Missile Research Institute, Luoyang 471099, China
*
Author to whom correspondence should be addressed.
Appl. Sci. 2020, 10(2), 658; https://doi.org/10.3390/app10020658
Received: 13 December 2019 / Revised: 9 January 2020 / Accepted: 13 January 2020 / Published: 16 January 2020
(This article belongs to the Section Optics and Lasers)
Aiming at improving the speed and accuracy of auto-focus for telescope observation, algorithms for image estimation and auto-focus were investigated and are discussed in this article. Based on the image quality assessment, the auto-focusing process of the telescope system is realized by using the mountain-climb search method. Several evaluation functions were tested in different scenarios. It is demonstrated that the Tenengrad image estimation function (IEF) is suitable for an instant and accurate auto-focus process of the telescope. Furthermore, we implemented sampling and dynamic adaptive focusing window (ES-DAFW) methods with the Tenengrad IEF to enhance the sensitivity and accuracy of the auto-focus process. The experimental results showed that our ES-DATW method can provide more accurate results in less time for the auto-focus process compared to the conventional approaches, especially for a sparse image. These results promise significant applications to the auto-focusing of other telescopes with image quality assessment. View Full-Text
Keywords: auto-focus; telescope observation; image quality; dynamic adaptive focusing window; Tenengrad function auto-focus; telescope observation; image quality; dynamic adaptive focusing window; Tenengrad function
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MDPI and ACS Style

Yang, C.; Chen, M.; Zhou, F.; Li, W.; Peng, Z. Accurate and Rapid Auto-Focus Methods Based on Image Quality Assessment for Telescope Observation. Appl. Sci. 2020, 10, 658.

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