HDR Imaging With Quanta Image Sensors: Theoretical Limits and Optimal Reconstruction

Gnanasambandam, Abhiram; Chan, Stanley H.

doi:10.1109/tci.2020.3041093

Cited by 27 publications

(8 citation statements)

References 48 publications

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“…• Again, in the absence of read noise, the optimal threshold for an arbitrary exposure is the one that makes the bitdensity equal to 0.5 over the space-time volume [42]. • Dynamic range of the one-bit sensor is generally wider than a convention CMOS pixel because one-bit sensors can perform multiple exposures bracketing [41], [43]- [45].…”

Section: B What Theoretical Results Are Available?mentioning

confidence: 99%

What Does a One-Bit Quanta Image Sensor Offer?

Chan

2022

IEEE Trans. Comput. Imaging

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The one-bit quanta image sensor (QIS) is a photoncounting device that captures image intensities using binary bits. Assuming that the analog voltage generated at the floating diffusion of the photodiode follows a Poisson-Gaussian distribution, the sensor produces either a "1" if the voltage is above a certain threshold or "0" if it is below the threshold. The concept of this binary sensor has been proposed for more than a decade and physical devices have been built to realize the concept. However, what benefits does a one-bit QIS offer compared to a conventional multi-bit CMOS image sensor? Besides the known empirical results, are there theoretical proofs to support these findings?The goal of this paper is to provide new theoretical support from a signal processing perspective. In particular, it is theoretically found that the sensor can offer three benefits: (1) Low-light: One-bit QIS performs better at low-light because it has a low read noise and its one-bit quantization can produce an error-free measurement. However, this requires the exposure time to be appropriately configured. (2) Frame rate: One-bit sensors can operate at a much higher speed because a response is generated as soon as a photon is detected. However, in the presence of read noise, there exists an optimal frame rate beyond which the performance will degrade. A Closed-form expression of the optimal frame rate is derived. (3) Dynamic range: Onebit QIS offers a higher dynamic range. The benefit is brought by two complementary characteristics of the sensor: nonlinearity and exposure bracketing. The decoupling of the two factors is theoretically proved, and closed-form expressions are derived.

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Section: B What Theoretical Results Are Available?mentioning

confidence: 99%

What Does a One-Bit Quanta Image Sensor Offer?

Chan

2022

IEEE Trans. Comput. Imaging

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“…When Vetterli and colleagues presented the analysis of the quanta image sensor in 2012 [7], this definition was already used to derive the Cramer-Rao lower bound. Subsequent papers such as [12] and [14] by Chan and colleagues also rely on this definition. A version for single-photon avalanche diode (SPAD) is presented by Gupta and colleagues [15].…”

Section: B Defining the Snrmentioning

confidence: 99%

“…The solution to (32) has been derived and reported by Gnanasambandam and Chan in [14]. It was found that the optimal weight is…”

Section: A High Dynamic Range Image Reconstructionmentioning

confidence: 99%

Exposure-Referred Signal-to-Noise Ratio for Digital Image Sensors

Gnanasambandam¹,

Chan²

2021

Preprint

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“…These effects are so important parts of the photographic experience that even virtual reality photography simulates them [2]. While the special or individual choice of exposure time (and the corresponding aperture) allows for expressing the photographer's creativity and feelings about the scene, technical systems may use various exposure times to create optimal results, e.g., in High Dynamic Range (HDR) photography [3][4][5][6]. Imaging systems are utilized in various technical fields, where the shutter speed is set to achieve the requirements of the application; e.g., when high speed fluid flows are measured using interferometry, the exposure time is set very short (as low as a few microseconds) to prevent motion blur [7,8], while in astronomical photography extremely long exposures times (even days) may be used to provide good signal to noise ratio [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

The Way to Modern Shutter Speed Measurement Methods: A Historical Overview

Simon

Vakulya

Ratosi

2022

Sensors

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Exposure time is a fundamental parameter for the photographer when the photo is composed, and the exact length of the exposure may be an essential determinant of performance in certain camera-based applications, e.g., optical camera communication (OCC) systems. There can be several reasons to measure the shutter speed of a camera: shutter speed may be checked at the time of manufacturing; it may be necessary to recheck in case of an elder camera model; it may be necessary to be measured if its exact value is not provided by the manufacturer; or a precise measurement may be necessary for a demanding application. In this paper various methods for shutter speed measurement are reviewed, presenting and analyzing methods that are still relevant today either for manufacturers, service personnel, amateur photographers, or the developers of camera-based systems. Each presented method is illustrated by real measurement results and the performance properties of the methods are also presented.

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HDR Imaging With Quanta Image Sensors: Theoretical Limits and Optimal Reconstruction

Cited by 27 publications

References 48 publications

What Does a One-Bit Quanta Image Sensor Offer?

What Does a One-Bit Quanta Image Sensor Offer?

Exposure-Referred Signal-to-Noise Ratio for Digital Image Sensors

The Way to Modern Shutter Speed Measurement Methods: A Historical Overview

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