Exposition (photographie)

L'exposition en photographie, anciennement nommée lumination, désigne la quantité totale de lumière reçue par la surface sensible (pellicule argentique ou capteur numérique) pendant la prise de vue. L’exposition est mesurée en lux.seconde (lx.s) et peut être calculée à partir de l’indice de lumination et de la luminance de la scène. De nombreux supports photographiques sont également sensibles à la lumière invisible, ce qui peut être un inconvénient ou un effet recherché, comme en photographie infrarouge. thumb|upright=3|La même scène photographiée avec un temps de pose compris entre 1,3 et 15 secondes et une ouverture constante. Exposition optimale D’un point de vue artistique, l’exposition « correcte » est celle qui restitue au mieux l’effet recherché par le photographe. Gamme dynamique D’un point de vue plus technique, une surface sensible a une « latitude de pose », ou « gamme dynamique », limitée. Si la luminosité d’une partie de la scène est au-delà

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1ère année: bases nécessaires à la représentation informatique 2D (3D). Passage d'un à plusieurs logiciels: compétence de choisir les outils adéquats en 2D et en 3D. Mise en relation des outils de CAO et DIM: regard critique et aptitude à choisir les méthodes nécessaires au résultat recherché.

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A 500 x 500 Dual-Gate SPAD Imager With 100% Temporal Aperture and 1 ns Minimum Gate Length for FLIM and Phasor Imaging Applications

Andrei Ardelean, Claudio Bruschini, Edoardo Charbon, Paul Mos, Arin Can Ülkü, Michael Alan Wayne

In this article, we report on SwissSPAD3 (SS3), a 500 x 500 pixel single-photon avalanche diode (SPAD) array, fabricated in 0.18-mu m CMOS technology. In this sensor, we introduce a novel dual-gate architecture with two contiguous temporal windows, or gates, guaranteed by the circuit architecture to be nonoverlapping and covering the totality of the sensor's exposure period. The gates can be adjusted with a temporal resolution of 17.9 ps, and the minimum measured gate width is 0.99 ns; to our knowledge, the shortest reported to date among large-format SPAD imagers. In the dual-channel mode, the burst frame rate is 49.8 and 97.7 kframes/s in the single-channel mode. A 2690-MB/s PCI express (PCIe) interface has been added to the data acquisition framework, enabling continuous operation at approximately 44 and 88 kframes/s. Due to optimizations of the gate-signal tree, we achieved a significant reduction to gate skew and gate width variation, which is negligible with respect to the SPAD temporal jitter. These improvements, along with sub-10-cps dark count rate (DCR) per pixel and 50% maximum photon detection probability (PDP), result in a sensor particularly well suited for fast acquisition fluorescence lifetime imaging microscopy (FLIM) experiments, for which we demonstrate reduced dispersion versus a single-gated sensor.

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2022

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Robust Multi-View Change Detection

Jérôme Berclaz, François Fleuret, Pascal Fua, Alessandro Lanza

We present a multi-view change detection approach aimed at being robust with respect to common “disturbance factors” yielding image changes in realworld applications. Disturbance factors causing “slow” or “fast-and-global” image variations, such as light changes and dynamic adjustments of camera parameters (e.g. auto-exposure and auto-gain control), are dealt with by a proper single-view change detector run independently on each view. The computed change masks are then fused into a “synergy mask” defined into a common virtual top-view, so as to detect and filter-out “fast-and-local” image changes due to physical points lying on the ground surface (e.g. shadows cast by moving objects and light spots hitting the ground surface).

2007

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Pro-oxidant effects of nano-TiO2 on Chlamydomonas reinhardtii during short-term exposure

Paul Bowen, Amarnath Jayaprakash, Volodymyr Koman, Olivier Martin, Lionel André Maurizi, Christian Santschi, Nadia Rachel Von Moos

This study sheds light on the short-term dynamics of pro-oxidant processes related to the exposure of C. reinhardtii microalgae to nano-TiO2 using (a) conventional fluorescence probes for cellular pro-oxidant process and (b) a recently developed cytochrome c biosensor for the continuous quantification of extracellular H2O2. The main aims are to investigate nano-TiO2 toxicity and the modifying factors thereof based on the paradigm of oxidative stress and to explore the utility of extracellular H2O2 as a potential biomarker of the observed cellular responses. This is the first study to provide continuous quantitative data on abiotic and biotic nano-TiO2-driven H2O2 generation to systematically investigate the link between extracellular and cellular pro-oxidant responses. Acute exposures of 1 h were performed in two different exposure media (MOPS and lake water), with nominal particle concentrations from 10 mg L-1 to 200 mg L-1, with and without UV pre-illumination. Abiotic and biotic extracellular H2O2 were continuously measured with the biosensor and complemented with endpoints for abiotic ROS (H2DCF-DA), oxidative stress (CellROX (R) Green) and damage (propidium iodide) measured by flow cytometry at the beginning and end of exposure. Results showed that nano-TiO2 suspensions generated ROS under UV light (abiotic origin) and promoted ROS accumulation in C. reinhardtii (biotic origin). However, extracellular and intracellular pro-oxidant processes differed. Hence, extracellular H2O2 cannot per se serve as a predictor of cellular oxidative stress or damage. The main predictors best describing the cellular responses included "exposure medium", "exposure time", "UV treatment" as well as "exposure concentration".

Royal Soc Chemistry2016

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Photographie

vignette|Mère migrante (Migrant Mother), photographie de Dorothea Lange, 1936. thumb|redresse|Dali Atomicus, photographie de Philippe Halsman mettant en scène Salvador Dalí. vignette|Une photographie

Pellicule photographique

:Les pellicules utilisées par le cinéma et la photo sont assez proches ; cet article ne traite toutefois que de celles destinées à réaliser des photographies.Pour les pellicules utilisées par le

Ouverture (photographie)