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Autofocus for multispectral camera using focus symmetry |
Applied Optics, Vol. 51, Issue 14, pp. 2616-2623 (2012)
http://dx.doi.org/10.1364/AO.51.002616
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Abstract
A multispectral camera acquires spectral color images with high fidelity by splitting the light spectrum into more than three bands. Because of the shift of focal length with wavelength, the focus of each channel should be mechanically adjusted in order to obtain sharp images. Because progressive adjustment is quite time consuming, the clear focus must be determined by using a limited number of images. This paper exploits the symmetry of focus measure distribution and proposes a simple yet efficient autofocus method. The focus measures are computed using first-order image derivatives, and the focus curve is obtained by spline interpolation. The optimal focus position, which maximizes the symmetry of the focus measure distribution, is then computed according to distance metrics. The effectiveness of the proposed method is validated in the multispectral camera system, and it is also applicable to relevant imaging systems.
© 2012 Optical Society of America
OCIS Codes
(100.3020) Image processing : Image reconstruction-restoration
(330.1710) Vision, color, and visual optics : Color, measurement
(110.4234) Imaging systems : Multispectral and hyperspectral imaging
ToC Category:
Imaging Systems
History
Original Manuscript: January 3, 2012
Revised Manuscript: February 15, 2012
Manuscript Accepted: March 10, 2012
Published: May 8, 2012
Virtual Issues
Vol. 7, Iss. 7 Virtual Journal for Biomedical Optics
Citation
Hui-Liang Shen, Zhi-Huan Zheng, Wei Wang, Xin Du, Si-Jie Shao, and John H. Xin, "Autofocus for multispectral camera using focus symmetry," Appl. Opt. 51, 2616-2623 (2012)
http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-51-14-2616
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