4 October 2016 Coded aperture solution for improving the performance of traffic enforcement cameras
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A coded aperture camera is proposed for automatic license plate recognition (ALPR) systems. It captures images using a noncircular aperture. The aperture pattern is designed for the rapid acquisition of high-resolution images while preserving high spatial frequencies of defocused regions. It is obtained by minimizing an objective function, which computes the expected value of perceptual deblurring error. The imaging conditions and camera sensor specifications are also considered in the proposed function. The designed aperture improves the depth of field (DoF) and subsequently ALPR performance. The captured images can be directly analyzed by the ALPR software up to a specific depth, which is 13 m in our case, though it is 11 m for the circular aperture. Moreover, since the deblurring results of images captured by our aperture yield fewer artifacts than those captured by the circular aperture, images can be first deblurred and then analyzed by the ALPR software. In this way, the DoF and recognition rate can be improved at the same time. Our case study shows that the proposed camera can improve the DoF up to 17 m while it is limited to 11 m in the conventional aperture.
© 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
Mina Masoudifar, Hamid Reza Pourreza, "Coded aperture solution for improving the performance of traffic enforcement cameras," Optical Engineering 55(10), 104101 (4 October 2016). https://doi.org/10.1117/1.OE.55.10.104101 . Submission:


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