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Proceedings Paper

Evaluation of sharpness measures and search algorithms for the auto focusing of high-magnification images
Author(s): Yi Yao; Besma Abidi; Narjes Doggaz; Mongi Abidi
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Paper Abstract

Digital imaging systems with extreme zoom capabilities are traditionally found in astronomy and wild life monitoring. More recently, the need for such capabilities has extended to long range surveillance and wide area monitoring such as forest fires, airport perimeters, harbors, and waterways. Auto-focusing is an indispensable function for imaging systems designed for such applications. This paper studies the feasibility of an image based passive auto-focusing control for high magnification systems based on off-the-shelf telescopes and digital cameras/camcorders, with concentration on two associated elements: the cost function (usually the image sharpness measure) and the search strategy. An extensive review of existing sharpness measures and search algorithms is conducted and their performances compared. In addition, their applicability and adaptability to a wide range of high magnifications (50×~1500×) are addressed. This study builds up the foundation for the development of auto-focusing schemes with particular applications to high magnification systems.

Paper Details

Date Published: 12 May 2006
PDF: 12 pages
Proc. SPIE 6246, Visual Information Processing XV, 62460G (12 May 2006); doi: 10.1117/12.664751
Show Author Affiliations
Yi Yao, The Univ. of Tennessee (United States)
Besma Abidi, The Univ. of Tennessee (United States)
Narjes Doggaz, The Univ. of Tennessee (United States)
Mongi Abidi, The Univ. of Tennessee (United States)


Published in SPIE Proceedings Vol. 6246:
Visual Information Processing XV
Zia-ur Rahman; Stephen E. Reichenbach; Mark A. Neifeld, Editor(s)

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