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Frequency Analysis of Transient Light Transport with Applications in Bare Sensor Imaging
"... Abstract. Light transport has been analyzed extensively, in both the primal domain and the frequency domain; the latter provides intuition of effects introduced by free space propagation and by optical elements, and allows for optimal designs of computational cameras for tailored, efficient informat ..."
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Abstract. Light transport has been analyzed extensively, in both the primal domain and the frequency domain; the latter provides intuition of effects introduced by free space propagation and by optical elements, and allows for optimal designs of computational cameras for tailored, efficient information capture. Here, we relax the common assumption that the speed of light is infinite and analyze free space propagation in the frequency domain considering spatial, temporal, and angular light variation. Using this analysis, we derive analytic expressions for crossdimensional information transfer and show how this can be exploited for designing a new, time-resolved bare sensor imaging system.
FlatCam: Thin, Bare-Sensor Cameras using Coded Aperture and Computation
, 2015
"... FlatCam is a thin form-factor lensless camera that consists of a coded mask placed on top of a bare, conventional sensor array. Unlike a traditional, lens-based camera where an image of the scene is directly recorded on the sensor pixels, each pixel in FlatCam records a linear combination of light f ..."
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Cited by 1 (0 self)
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FlatCam is a thin form-factor lensless camera that consists of a coded mask placed on top of a bare, conventional sensor array. Unlike a traditional, lens-based camera where an image of the scene is directly recorded on the sensor pixels, each pixel in FlatCam records a linear combination of light from multiple scene elements. A computational algorithm is then used to demultiplex the recorded measurements and reconstruct an image of the scene. FlatCam is an instance of a coded aperture imaging system; however, unlike the vast majority of related work, we place the coded mask extremely close to the image sensor that can enable a thin system. We employ a separable mask to ensure that both calibration and image reconstruction are scalable in terms of memory requirements and computational complexity. We demonstrate the potential of the FlatCam design using two prototypes: one at visible wavelengths and one at infrared wavelengths.
A Switchable Light Field Camera Architecture with Angle Sensitive Pixels and Dictionary-based Sparse Coding
"... We propose a flexible light field camera architecture that is at the convergence of optics, sensor electronics, and ap-plied mathematics. Through the co-design of a sensor that comprises tailored, Angle Sensitive Pixels and advanced re-construction algorithms, we show that—contrary to light field ca ..."
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We propose a flexible light field camera architecture that is at the convergence of optics, sensor electronics, and ap-plied mathematics. Through the co-design of a sensor that comprises tailored, Angle Sensitive Pixels and advanced re-construction algorithms, we show that—contrary to light field cameras today—our system can use the same measure-ments captured in a single sensor image to recover either a high-resolution 2D image, a low-resolution 4D light field using fast, linear processing, or a high-resolution light field using sparsity-constrained optimization. 1.
1FlatCam: Thin, Bare-Sensor Cameras using Coded Aperture and Computation
"... FlatCam is a thin form-factor lensless camera that consists of a coded mask placed on top of a bare, conventional sensor array. Unlike a traditional, lens-based camera where an image of the scene is directly recorded on the sensor pixels, each pixel in FlatCam records a linear combination of light f ..."
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FlatCam is a thin form-factor lensless camera that consists of a coded mask placed on top of a bare, conventional sensor array. Unlike a traditional, lens-based camera where an image of the scene is directly recorded on the sensor pixels, each pixel in FlatCam records a linear combination of light from multiple scene elements. A computational algorithm is then used to demultiplex the recorded measurements and reconstruct an image of the scene. FlatCam is an instance of a coded aperture imaging system; however, unlike the vast majority of related work, we place the coded mask extremely close to the image sensor that can enable a thin system. We employ a separable mask to ensure that both calibration and image reconstruction are scalable in terms of memory requirements and computational complexity. We demonstrate the potential of the FlatCam design using two prototypes: one at visible wavelengths and one at infrared wavelengths. I.
Robustness of Planar Fourier Capture Arrays to Colour Changes and Lost Pixels
"... ABSTRACT: Planar Fourier capture arrays (PFCAs) are optical sensors built entirely in standard mi-crochip manufacturing flows. PFCAs are composed of ensembles of angle sensitive pixels (ASPs) that each report a single coefficient of the Fourier transform of the far-away scene. Here we charac-terize ..."
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ABSTRACT: Planar Fourier capture arrays (PFCAs) are optical sensors built entirely in standard mi-crochip manufacturing flows. PFCAs are composed of ensembles of angle sensitive pixels (ASPs) that each report a single coefficient of the Fourier transform of the far-away scene. Here we charac-terize the performance of PFCAs under the following three non-optimal conditions. First, we show that PFCAs can operate while sensing light of a wavelength other than the design point. Second, if only a randomly-selected subset of 10 % of the ASPs are functional, we can nonetheless reconstruct the entire far-away scene using compressed sensing. Third, if the wavelength of the imaged light is unknown, it can be inferred by demanding self-consistency of the outputs.
Imagers and Sensors
"... Abstract—We describe the optical, mathematical and compu-tational foundations for a new class of lensless, ultra-miniature computational imagers and image sensors. Such sensors employ phase gratings that have provably optimal optical properties and are integrated with CMOS photodetector matrices. Th ..."
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Abstract—We describe the optical, mathematical and compu-tational foundations for a new class of lensless, ultra-miniature computational imagers and image sensors. Such sensors employ phase gratings that have provably optimal optical properties and are integrated with CMOS photodetector matrices. These imagers have no lens and can thus be made extremely small (∼100 µm) and very inexpensive (a few Euro cents). Because the apertures are small, they have an effective depth of field ranging from roughly 1 mm to infinity. The grating acts as a two-dimensional visual “chirp ” and preserves image power throughout the Fourier plane; thus the captured signals preserve image information. The final digital image is not captured as in a traditional camera but is instead computed from raw photodetector signals. The novel representation at the photodetectors demands powerful algorithms such as deconvolution, Bayesian estimation, or matrix
