Light-Field Imaging Toolkit

Bolan, Jeffrey; Hall, Elise; Clifford, Christopher J.; Thurow, Brian S.

doi:10.1016/j.softx.2016.05.004

Cited by 18 publications

(11 citation statements)

References 8 publications

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“…The raw image of I ( s , t ) is initially calibrated to assign the center position of individual microimages and then converted to the 4D radiance arrays of L ( u , v , s , t ) with the light‐field imaging toolkit (LFIT v2.4). [ 33 ] The disparity map is estimated using a cost volume‐based stereomatching algorithm, [ 16 ] which measures the similarity between the center view and the sub‐aperture images and matches the cost of different disparity labels to estimate the stereo‐correspondences with sub‐label precision. In addition, the camera matrices, that is, intrinsic ([ K ]) and extrinsic matrices ([ R | t ]), are calculated from a raw checker board image with a known pattern size using the geometric calibration algorithm [ 34 ] (more light‐field reconstruction and depth map results in Figure S4, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Machine‐Learned Light‐Field Camera that Reads Facial Expression from High‐Contrast and Illumination Invariant 3D Facial Images

Bae

Lee

Kwon

et al. 2021

Advanced Intelligent Systems

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Facial expression conveys nonverbal communication information to help humans better perceive physical or psychophysical situations. Accurate 3D imaging provides stable topographic changes for reading facial expression. In particular, light‐field cameras (LFCs) have high potential for constructing depth maps, thanks to a simple configuration of microlens arrays and an objective lens. Herein, machine‐learned NIR‐based LFCs (NIR‐LFCs) for facial expression reading by extracting Euclidean distances of 3D facial landmarks in pairwise fashion are reported. The NIR‐LFC contains microlens arrays with asymmetric Fabry−Perot filter and NIR bandpass filter on CMOS image sensor, fully packaged with two vertical‐cavity surface‐emitting lasers. The NIR‐LFC not only increases the image contrast by 2.1 times compared with conventional LFCs, but also reduces the reconstruction errors by up to 54%, regardless of ambient illumination conditions. A multilayer perceptron (MLP) classifies input vectors, consisting of 78 pairwise distances on the facial depth map of happiness, anger, sadness, and disgust, and also exhibits exceptional average accuracy of 0.85 (p<0.05). This LFC provides a new platform for quantitatively labeling facial expression and emotion in point‐of‐care biomedical, social perception, or human−machine interaction applications.

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Section: Resultsmentioning

confidence: 99%

Machine‐Learned Light‐Field Camera that Reads Facial Expression from High‐Contrast and Illumination Invariant 3D Facial Images

Bae

Lee

Kwon

et al. 2021

Advanced Intelligent Systems

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“…DHMx runs under Linux and is open-source (https://github.com/ dhm-org/dhm_suite). FLFM reconstruction was performed using another group's open-source package [14]. Full amplitude and phase reconstructions were made using custom Fiji plug-ins that we have published previously [15].…”

Section: Resultsmentioning

confidence: 99%

ELVIS: A Correlated Light-Field and Digital Holographic Microscope for Field and Laboratory Investigations

et al. 2020

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“…The raw microimages were separated into R, G, and B channels, and then reconstructed into a 4D radiance array of L ( u , v , s , t ) for each channel microimage using the Light‐field imaging toolkit. [ 31 ] The 4D arrays with different color channels were combined to form 5D radiance arrays of L ( u , v , s , t , c ). Light‐field images from the 5D arrays contain optical aberrations caused by the objective lens and the MLA as shown in Figure S10, Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

“…The captured raw microimages were calibrated for high contrast light‐field imaging by using the Light‐field Imaging Toolkit [ 31 ] and finally reconstructed for a disparity map by using an open disparity calculation toolbox based on cost volume filtering [ 32 ] The light‐field data consist of 5D matrices (43 × 43 × 116 × 85 × 3), including spatial and directional 4D data and RGB color indices. The photograph of fully integrated ULFC is as shown in Figure a.…”

Section: Figurementioning

confidence: 99%

High Contrast Ultrathin Light‐Field Camera Using Inverted Microlens Arrays with Metal–Insulator–Metal Optical Absorber

Bae

Kim

Jang

et al. 2021

Advanced Optical Materials

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Light‐field imaging has attracted much attention in constructing 3D objects with a simple configuration and capturing all the spatial and directional data in a single photographic exposure. Here, an ultrathin light‐field camera (ULFC) for high contrast and high‐resolution light‐field imaging using a metal–insulator–metal optical absorber based inverted microlens arrays (MIM‐iMLA) is reported. A metal–insulator–metal based optical absorber (MIM‐OA) between microlenses exhibits high light absorption in the full visible region, thereby highly blocking microlens crosstalk. The MIM‐iMLA double the image contrast and improve MTF50 by up to 32%, compared to conventional light‐field image. In addition, the MIM‐iMLA substantially reduces an image plane distance and brings the objective lens position closer to the MLA. The ULFC exhibits a short total track length of 5.1 mm, demonstrating high contrast light‐field image acquisition and high accuracy 3D depth map estimation after light‐field rendering. This ultrathin and high contrast light‐field camera can provide a new platform for miniaturized 3D cameras in biomedical applications, biometrics, automated inspection, or mobile camera applications.

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Light-Field Imaging Toolkit

Cited by 18 publications

References 8 publications

Machine‐Learned Light‐Field Camera that Reads Facial Expression from High‐Contrast and Illumination Invariant 3D Facial Images

Machine‐Learned Light‐Field Camera that Reads Facial Expression from High‐Contrast and Illumination Invariant 3D Facial Images

ELVIS: A Correlated Light-Field and Digital Holographic Microscope for Field and Laboratory Investigations

High Contrast Ultrathin Light‐Field Camera Using Inverted Microlens Arrays with Metal–Insulator–Metal Optical Absorber

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