An Algorithm and Architecture Design for Light Field Based Digital Refocusing
Date Issued
2010
Date
2010
Author(s)
Chen, Chih-Chieh
Abstract
In this thesis, a computational photography system is utilized to sample 4D light fields. The system is implemented using a normal DSLR camera with a mask printed using Kodak LVT technique. We reconfigure the camera by inserting a pinhole array mask in front of the sensors. The mask blocks part of light and samples the rest that passes through the pinholes. With these 4D light field data, the refocused images are obtained by rearranging the captured sub-images. Thus, with our algorithm, we can adjust focus distances without a complex lens set..
Also, depth estimation of light field data obtained from the pinhole-masked camera system is proposed. In the first approach, the sharpness of objects in the refocused images is evaluated using FFT method, from which an empirical formula can be obtained to estimate the depth of objects. The second method uses the raw data in sub-images to calculate an index, Average Absolute Difference (AAD), for depth estimation purposes. The advantages and disadvantages of two proposed approaches are discussed and compared.
Finally, to speed up the process for future real-time application, we also implement hardware processor of our algorithm. The chip is implemented with TSMC 130 nm technology. The chip size is 2.178mm2, power consumption is 50.28mV, and the chip operates at 100 MHz when processing a captured image into a 640×480 image.
Subjects
light field
pinhole array mask
digital refocusing
depth estimation
Type
thesis
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