DocumentCode :
1278282
Title :
Geometric Calibration of Lens and Filter Distortions for Multispectral Filter-Wheel Cameras
Author :
Brauers, Johannes ; Aach, Til
Author_Institution :
Inst. of Imaging & Comput. Vision, RWTH Aachen Univ., Aachen, Germany
Volume :
20
Issue :
2
fYear :
2011
Firstpage :
496
Lastpage :
505
Abstract :
High-fidelity color image acquisition with a multispectral camera utilizes optical filters to separate the visible electromagnetic spectrum into several passbands. This is often realized with a computer-controlled filter wheel, where each position is equipped with an optical bandpass filter. For each filter wheel position, a grayscale image is acquired and the passbands are finally combined to a multispectral image. However, the different optical properties and non-coplanar alignment of the filters cause image aberrations since the optical path is slightly different for each filter wheel position. As in a normal camera system, the lens causes additional wavelength-dependent image distortions called chromatic aberrations. When transforming the multispectral image with these aberrations into an RGB image, color fringes appear, and the image exhibits a pincushion or barrel distortion. In this paper, we address both the distortions caused by the lens and by the filters. Based on a physical model of the bandpass filters, we show that the aberrations caused by the filters can be modeled by displaced image planes. The lens distortions are modeled by an extended pinhole camera model, which results in a remaining mean calibration error of only 0.07 pixels. Using an absolute calibration target, we then geometrically calibrate each passband and compensate for both lens and filter distortions simultaneously. We show that both types of aberrations can be compensated and present detailed results on the remaining calibration errors.
Keywords :
calibration; cameras; data acquisition; distortion; geometrical optics; image colour analysis; optical filters; color image acquisition; electromagnetic spectrum; filter distortions; geometric calibration; lens; multispectral filter-wheel cameras; optical filters; Cameras; Lenses; Optical distortion; Optical imaging; Optical sensors; Passband; Wheels; Camera calibration; chromatic aberration; geometric distortion; multispectral image processing; multispectral imaging model;
fLanguage :
English
Journal_Title :
Image Processing, IEEE Transactions on
Publisher :
ieee
ISSN :
1057-7149
Type :
jour
DOI :
10.1109/TIP.2010.2062193
Filename :
5530383
Link To Document :
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