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Image capture and processing for a microoptical compound-eye sensor

: Tudela, R.; Brückner, A.; Duparre, A.; Bräuer, A.


Schelkens, P. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Optical and Digital Image Processing : 7.-10.4.2008, Strasbourg, France
Bellingham, WA: SPIE, 2008 (SPIE Proceedings Series 7000)
ISBN: 978-0-8194-7198-7
ISBN: 0-8194-7198-4
ISSN: 0277-786X
Paper 700019
Conference "Optical and Digital Image Processing" <2008, Strasbourg>
Fraunhofer IOF ()

An artificial compound-eye imaging system has been developed consisting of one planar array of microlenses positioned on a spacing structure and coupled to a commercial CMOS optoelectronic detector array of different pitch, providing different viewing directions for the individual optical channels. Each microlens corresponds to one channel, which can be related to one or more pixels due to the different fill factors of the microlens array and the image sensor. Also alignment problems resulting from the matching of the microlens focal spots and the pixels during the assembly and the possible residual rotation between the artificial compound-eye objective and the pixel matrix are considered. We have written a program to automatically select the illuminated pixels of the sensor which correspond to each channel in order to form the final image. This calibration method is based on intensity criterions besides the geometric disposition of the microlens array. An image capture program that uses only the channels selected by the calibration is also presented. This program additionally implements image post-processing methods adapted to the microoptical compound-eye sensor. They are applied to the captured images in real time and allow increasing the contrast of the captured images. One of the methods used is the Wiener filter that is computed by taking into account an approximation of the multichannel imaging process of microoptical compound-eye sensors. Experimental results are presented, which show a noticeable increase in the frequency response when the Wiener filter is used, partially compensating the characteristic low spatial resolution of the artificial compound eyes.