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Hybrid Light Field Imaging for Improved Spatial Resolution and Depth Range

Abstract:

Light field imaging involves capturing both angular and spatial distribution of light; it enables new capabilities, such as post-capture digital refocusing, camera aperture adjustment, perspective shift, and depth estimation. Micro-lens array (MLA) based light field cameras provide a cost-effective approach to light field imaging. There are two main limitations of MLA-based light field cameras: low spatial resolution and narrow baseline. While low spatial resolution limits the general purpose use and applicability of light field cameras, narrow baseline limits the depth estimation range and accuracy. In this paper, we present a hybrid stereo imaging system that includes a light field camera and a regular camera. The hybrid system addresses both spatial resolution and narrow baseline issues of the MLA-based light field cameras while preserving light field imaging capabilities.

Publication(s):

"Hybrid stereo imaging including a light field and a regular camera,"
M Zeshan Alam and Bahadir K Gunturk,
Proceedings of 24th IEEE Signal Processing and Communication Application Conference (SIU), 2016 ,
Pages: 1293--1296
[PDF]

Funding:

TUBITAK grant 1003

Images:

Hybrid imaging system including a regular and a light field camera. The maximum baseline of the light field camera is limited by the camera main lens aperture, and is much less (about an order of magnitude) than the baseline (about 4cm) between the light field and the regular camera.

(Optical design)

Hybrid imaging system including a regular and a light field camera. The maximum baseline of the light field camera is limited by the camera main lens aperture, and is much less (about an order of magnitude) than the baseline (about 4cm) between the light field and the regular camera. 

(Optical hardware)

  Illustration of the resolution enhancement process.
Speeding up the optical flow estimation process.
(Top) Residual between the regular camera image and light field sub-aperture images before warping. Two sub-aperture images are highlighted. (Bottom) Residual between the regular camera image and light field subaperture images after warping.
Resolution enhancement of light field sub-aperture images. (a) One of the bicubically resized Lytro sub-aperture image. (b) Resolution-enhanced sub-aperture image using alpha blending. (c) Resolution-enhanced sub-aperture image using wavelet-based fusion.
Post-capture digital refocusing using shift-and-sum technique. (Top row) Lytro light field refocusing. (Middle row) Resolution-enhanced light field (using alpha blending) refocusing. (Bottom row) Comparison of zoomed-in regions. (a) Close-depth focus. (b) Middle-depth focus. (c) Far-depth focus.
(a) Disparity map between the leftmost and rightmost Lytro sub-aperture images. (b) Disparity map between the middle Lytro sub-aperture image and the regular camera image. (c) Disparities of the target object centers.