Locally adaptive active pixel sensors

Deval, Anant; Khan, Amjad; Akers, L.A.

doi:10.1109/iscas.1997.608948

Cited by 8 publications

(5 citation statements)

References 5 publications

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“…The actual decision of which mode to use has to be taken by an adaptive mechanism, whose goal is to keep the resulting pixel photocurrent within the range of downstream signal processing circuits [27]. Real-time local brightness adaptation was achieved by a 16-transistor controller which commands a 4-pixel cell [29].…”

Section: Multimode Image Sensorsmentioning

confidence: 99%

Predictive Multiple Sampling Algorithm With Overlapping Integration Intervals for Linear Wide Dynamic Range Integrating Image Sensors

Acosta-Serafini

Masaki

Sodini

2004

IEEE Trans. Intell. Transport. Syst.

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Machine vision systems are used in a wide range of applications such as security, automated quality control and intelligent transportation systems. Several of these systems need to extract information from natural scenes in the section of the electromagnetic spectrum visible to humans. These scenes can easily have intra-frame illumination ratios in excess of 10 6 : 1. Solid-state image sensors that can correctly process wide illumination dynamic range scenes are therefore required to to ensure correct reliability and performance.This thesis describes a new algorithm to linearly increase the illumination dynamic range range of integrating-type image sensors. A user-defined integration time is taken as a reference to create a potentially large set of integration intervals of different duration (the selected integration time being the longest) but with a common end. The light intensity received by each pixel in the sensing array is used to choose the optimal integration interval from the set, while a pixel saturation predictive decision is used to overlap the integration intervals within the given integration time such that only one frame using the optimal integration interval for each pixel is produced. The total integration time is never exceeded. Benefits from this approach are motion minimization, real-time operation, reduced memory requirements, programmable light intensity dynamic range increase and access to incremental light intensity information during the integration time. The algorithm is fully described with special attention to the resulting sensor transfer function, the signal-to-noise ratio, characterization of types and effects of errors in the predictive decision, calculation of the optimal integration intervals set given a certain set size, calculation of the optimal number of integration intervals, and impact of the new algorithm to image data compression.An efficient mapping of this algorithm to a CMOS process was done by designing a proof-of-concept integrated circuit in a 0.18µm 1.8V 5-metal layer process. The major components of the chip are a 1/3" VGA (640 × 480) pixel array, a 4bit per pixel memory array, an integration controller array and an analog-to-digital converter/correlated double sampled (ADC/CDS) array. Supporting components include pixel and memory row decoders, memory and converter output digital multiplexers, pixel-to-ADC/CDS analog multiplexer and test structures. The pixels have a fill factor of nearly 50%, as most of the needed system additions and complexity were taken off-pixel. The prototype is fully functional and linearly expands the dynamic range by more than 60dB.

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Section: Multimode Image Sensorsmentioning

confidence: 99%

Predictive Multiple Sampling Algorithm With Overlapping Integration Intervals for Linear Wide Dynamic Range Integrating Image Sensors

Acosta-Serafini

Masaki

Sodini

2004

IEEE Trans. Intell. Transport. Syst.

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“…Deval et al 20 proposed another version of this multimode sensor. Their version selects between bipolar and diode modes.…”

Section: Multimode Sensorsmentioning

confidence: 99%

Wide-dynamic-range sensors

Yadid-Pecht

1999

Opt. Eng

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The work done to provide image sensors (CCDs and CMOS) with a wide dynamic range is reviewed. The different classes of solutions, which consist of logarithmic sensors, ''clipped'' sensors, multimode sensors, frequency-based sensors, and sensors with control over integration time are described. The pros and cons of each solution are discussed, and some new experimental results are shown. Active pixel sensors with a wide dynamic range are analyzed and possible future directions are pointed out. © 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)01610-4] Subject terms: image sensors; wide dynamic range; detector arrays; image quality; image reconstruction; very large scale integration; complementary metal oxide semiconductor image sensor; charge-coupled device; active pixel sensor.Paper 980463

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“…5 Adaptive circuitry has also been developed which varied the shutter speed and gain to prevent saturation and improve sensitivity in photodetectors. 6 The integrated electrostatic chopper will provide a mechanism for simple, more precise control of chopper function such that the device can adjust to variability in the sensing environment. For example, dynamic thermal recalibration can be achieved for IR staring arrays by varying the duty cycle in order to provide reasonable gain and level *dausch@mcnc.…”

Section: Introductionmentioning

confidence: 99%

Chopping of near- and mid-infrared radiation using a curled electrostatic MEMS actuator

Dausch

Goodwin

2003

SPIE Proceedings

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An electrostatic MEMS actuator known as the "Artificial Eyelid" can be used as a micromechanical chopper for IR detectors. The actuator structure consists of a curled polymer/metal film stack which is microfabricated and released from an IR transparent substrate. The film stack is uncurled by applying an electric field between the curled film and the transparent fixed electrode on the substrate. These flexible film actuators can act as IR choppers, providing transmission of radiation to the sensor elements when open (curled) and reflection when closed (uncurled). Arrays of actuators were fabricated on ITOcoated glass substrates and ranged in size from 4 x 4 mm to 7.5 x 15 mm with individual elements ranging from 250 to 500 µm on a side. Actuation for devices with average radius of curvature of 120 µm was consistently achieved at 150-170 V operation with 98-100% of the elements functioning and long lifetimes. IR chopper characteristics were measured using a blackbody source and pyroelectric detector by applying sine and square wave voltage to the actuators at a frequency of 30 Hz. The capability of the artificial eyelid for chopping near-and mid-IR radiation, including future fabrication of devices using NiCo 2 O 4 or NiRh 2 O 4 films for IR transparent electrodes, will be discussed.

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Locally adaptive active pixel sensors

Cited by 8 publications

References 5 publications

Predictive Multiple Sampling Algorithm With Overlapping Integration Intervals for Linear Wide Dynamic Range Integrating Image Sensors

Predictive Multiple Sampling Algorithm With Overlapping Integration Intervals for Linear Wide Dynamic Range Integrating Image Sensors

Wide-dynamic-range sensors

Chopping of near- and mid-infrared radiation using a curled electrostatic MEMS actuator

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