A night-time outdoor data set for low-light enhancement

2020 ◽  
Author(s):  
Yudong Zhou ◽  
Ronggang Wang ◽  
Yang Zhao
Keyword(s):  
Night Time ◽  
Low Light ◽  
Data Set ◽  
Light Enhancement

scholarly journals Photogrammetric Digital Surface Model Reconstruction in Extreme Low-Light Environments

2021 ◽  
Vol 13 (7) ◽  
pp. 1261
Author(s):  
Riccardo Roncella ◽  
Nazarena Bruno ◽  
Fabrizio Diotri ◽  
Klaus Thoeni ◽  
Anna Giacomini
Keyword(s):  
Image Quality ◽  
Image Quality Assessment ◽  
High Sensitivity ◽  
Sensor Technology ◽  
Surface Model ◽  
Night Time ◽  
Low Light ◽  
Reduction Techniques ◽  
Geometrical Information ◽  
Imaging Sensors

Digital surface models (DSM) have become one of the main sources of geometrical information for a broad range of applications. Image-based systems typically rely on passive sensors which can represent a strong limitation in several survey activities (e.g., night-time monitoring, underground survey and night surveillance). However, recent progresses in sensor technology allow very high sensitivity which drastically improves low-light image quality by applying innovative noise reduction techniques. This work focuses on the performances of night-time photogrammetric systems devoted to the monitoring of rock slopes. The study investigates the application of different camera settings and their reliability to produce accurate DSM. A total of 672 stereo-pairs acquired with high-sensitivity cameras (Nikon D800 and D810) at three different testing sites were considered. The dataset includes different camera configurations (ISO speed, shutter speed, aperture and image under-/over-exposure). The use of image quality assessment (IQA) methods to evaluate the quality of the images prior to the 3D reconstruction is investigated. The results show that modern high-sensitivity cameras allow the reconstruction of accurate DSM in an extreme low-light environment and, exploiting the correct camera setup, achieving comparable results to daylight acquisitions. This makes imaging sensors extremely versatile for monitoring applications at generally low costs.

Perceptual Quality Assessment of Low-light Image Enhancement

2021 ◽  
Vol 17 (4) ◽  
pp. 1-24
Author(s):  
Guangtao Zhai ◽  
Wei Sun ◽  
Xiongkuo Min ◽  
Jiantao Zhou
Keyword(s):  
Image Quality ◽  
Quality Assessment ◽  
Image Enhancement ◽  
Dynamic Range ◽  
State Of The Art ◽  
Perceptual Quality ◽  
Low Light ◽  
Light Image ◽  
Light Enhancement

Low-light image enhancement algorithms (LIEA) can light up images captured in dark or back-lighting conditions. However, LIEA may introduce various distortions such as structure damage, color shift, and noise into the enhanced images. Despite various LIEAs proposed in the literature, few efforts have been made to study the quality evaluation of low-light enhancement. In this article, we make one of the first attempts to investigate the quality assessment problem of low-light image enhancement. To facilitate the study of objective image quality assessment (IQA), we first build a large-scale low-light image enhancement quality (LIEQ) database. The LIEQ database includes 1,000 light-enhanced images, which are generated from 100 low-light images using 10 LIEAs. Rather than evaluating the quality of light-enhanced images directly, which is more difficult, we propose to use the multi-exposure fused (MEF) image and stack-based high dynamic range (HDR) image as a reference and evaluate the quality of low-light enhancement following a full-reference (FR) quality assessment routine. We observe that distortions introduced in low-light enhancement are significantly different from distortions considered in traditional image IQA databases that are well-studied, and the current state-of-the-art FR IQA models are also not suitable for evaluating their quality. Therefore, we propose a new FR low-light image enhancement quality assessment (LIEQA) index by evaluating the image quality from four aspects: luminance enhancement, color rendition, noise evaluation, and structure preserving, which have captured the most key aspects of low-light enhancement. Experimental results on the LIEQ database show that the proposed LIEQA index outperforms the state-of-the-art FR IQA models. LIEQA can act as an evaluator for various low-light enhancement algorithms and systems. To the best of our knowledge, this article is the first of its kind comprehensive low-light image enhancement quality assessment study.

Quantifying heating biases in marine air temperature observations, ~1790 - present

2021 ◽  
Author(s):  
Thomas Cropper ◽  
Elizabeth Kent ◽  
David Berry ◽  
Richard Cornes ◽  
Beatriz Recinos-Rivas
Keyword(s):  
Air Temperature ◽  
Diurnal Cycle ◽  
Surface Air Temperature ◽  
Night Time ◽  
Data Set ◽  
Near Surface ◽  
Marine Surface ◽  
Heating Model ◽  
Marine Air

<p>Accurate, long-term time series of near-surface air temperature (AT) are the fundamental datasets on which the magnitude of anthropogenic climate change is scientifically and societally addressed. Across the ocean, these (near-surface) climate records use Sea Surface Temperature (SST) instead of Marine Air Temperature (MAT) and blend the SST and AT over land to create datasets. MAT has often been overlooked as a data choice as daytime MAT observations from ships are known to contain warm biases due to the storage of accumulated solar energy. Two recent MAT datasets, CLASSnmat (1881 – 2019) and UAHNMAT (1900 – 2018), both use night-time MAT observations only. Daytime MAT observations in the International Comprehensive Ocean–Atmosphere Data Set (ICOADS) account for over half of the MAT observations in ICOADS, and this proportion increases further back in time (i.e. pre-1850s). If long-term MAT records over the ocean are to be extended, the use of daytime MAT is vital.</p><p> </p><p>To adjust for the daytime MAT heating bias, and apply it to ICOADS, we present the application of a physics-based model, which accounts for the accumulated energy storage throughout the day. As the ‘true’ diurnal cycle of MAT over the ocean has not been, to-date, adequately quantified, our approach also removes the diurnal cycle from ICOADS observations and generates a night-time equivalent MAT for all observations. We fit this model to MAT observations from groups of ships in ICOADS that share similar heating biases and metadata characteristics. This enables us to use the empirically derived coefficients (representing the physical energy transfer terms of the heating model) obtained from the fit for use in removal of the heating bias and diurnal cycle from ship-based MAT observations throughout ICOADS which share similar characteristics (i.e. we can remove the diurnal cycle from a ship which only reports once daily at noon). This adjustment will create an MAT record of night-time-equivalent temperatures that will enable an extension of the marine surface AT record back into the 18<sup>th</sup> century.</p>

LERANet: Low-light Enhancement Network based on Retinex and Attention

2021 ◽  
Author(s):  
Renjie He ◽  
Xintao Guo ◽  
Wei Zhou ◽  
Mingyi He
Keyword(s):  
Low Light ◽  
Light Enhancement

Effect of low light intensity at night on cow traffic in automatic milking systems

2014 ◽  
Vol 54 (10) ◽  
pp. 1784
Author(s):  
Fanny Hjalmarsson ◽  
Ingemar Olsson ◽  
Sabine Ferneborg ◽  
Sigrid Agenäs ◽  
Emma Ternman
Keyword(s):  
Light Intensity ◽  
Dairy Cows ◽  
Milk Yield ◽  
Negative Impact ◽  
Night Time ◽  
Low Light ◽  
Milking Frequency ◽  
Automatic Milking ◽  
Automatic Milking Systems ◽  
Reduced Light

Several studies have shown benefits of long-day (16 h) photoperiod in lactating dairy cows, but have not identified a suitable light intensity for the dark hours. It is known that the locomotion pattern of dairy cows is altered at low light intensities and this may translate to reduced cow traffic and milking frequency, which would have a negative impact on system productivity. However, it is also recognised that a significant disturbance of rest may have a negative impact on the health and productivity of high-yielding dairy cows. This study examined the effect of three different night-time light intensities (LOW: 11 ± 3, MED: 33 ± 1 and HIGH: 74 ± 6 lx) on number of gate passages, milking frequency and milk yield in dairy cows in automatic milking systems. The study was conducted in Sweden during the winter of 2012–13 and the treatments were applied in a crossover design to three herds with an automatic milking system. Minimum day time light intensity was 158 lx. Data on gate passages, milking frequency and milk yield for 172 ± 49 (mean ± s.d.) cows during the last 22 days of each 34-day study period were analysed for treatment differences and differences in daily distribution over 24 h, during day time and night time. Light intensity did not affect total number of gate passages per 24-h period and cow, but number of gate passages per hour and cow was in all treatments lower during night time than during day time. Milking frequency was increased in MED compared with both HIGH and LOW (P < 0.05). Milk yield decreased with reduced light intensity, and differed significantly between HIGH and LOW treatments, 45 ± 1 kg and 44 ± 1 kg, respectively (P < 0.001). Our conclusion is that reducing light intensity to 11 lx at night time does not affect cows’ general activity as gate passages remained the same for all treatments. However, milk yield decreased with reduced light intensity, which might be related to a lower feed intake. We argue that providing night light for dairy cows, as required by many welfare acts, might be related to production level rather than welfare aspects and that the recommendations should be revised.

Day- and night-time parental investment by incubating Wilson's Plovers in a tropical environment

1995 ◽  
Vol 73 (5) ◽  
pp. 879-886 ◽  
Author(s):  
Michel Thibault ◽  
Raymond McNeil
Keyword(s):  
Breeding Season ◽  
Nest Predation ◽  
Time Lapse ◽  
Video Camera ◽  
Nest Attendance ◽  
Night Time ◽  
Low Light ◽  
Charadrius Wilsonia ◽  
Infrared Lamps ◽  
Time Lapse Video

With the use of a time-lapse video camera and infrared lamps, we quantified diurnal and nocturnal incubation sex roles in 17 pairs of Wilson's Plovers (Charadrius wilsonia cinnamominus) breeding in northeastern Venezuela. More than 82% of nests reached the hatching stage. Between the laying of the last egg and hatching of the first one, parents devoted 83% of their time incubating. Males spent more time incubating than females. Males incubated mainly at night and females mostly during daytime. Males also spent significantly more time incubating during daytime than did females during nighttime. During incubation, females relieved males at dawn and males relieved females at dusk. By relieving each other under conditions of low light intensity, parents probably reduced nest predation. Outside the breeding season, the Wilson's Plovers forage almost exclusively during nighttime. In contrast, during the breeding season, males foraged mainly during daytime low tides, probably as a consequence of their nocturnal nest attendance. During short daytime periods, on cloudy days, incubating plovers, particularly the females, abandoned their eggs to forage.

scholarly journals Peculiarities of the environmental light pollution in Chernivtsi Region

2021 ◽  
pp. 66-75
Author(s):  
А. V. Zhuk ◽  
O. D. Zarochentseva
Keyword(s):  
Web Application ◽  
Industrial Development ◽  
Urban Expansion ◽  
Wildlife Habitat ◽  
Light Pollution ◽  
Analysis Tool ◽  
Night Time ◽  
Data Set ◽  
Rural Landscapes ◽  
Medical Disorders

Introduction. Every year industrial development and economic growth make light pollution worsen on a global scale. It is a well-known fact that artificial outdoor lighting causes destruction of wildlife habitat, impacts circadian rhythms of all living beings, disrupts animal behavior and leads to medical disorders of humans. Over the last decade scientists switched their focus from artificial sky glow over large cities to light pollution of rural landscapes, protected areas and roadways.  The purpose of this paper consists in assessing night-time light emissions over Chernivtsi Region as well as over city of Chernivtsi using satellite measurements. Methods. Measurements of night-time light emissions were obtained with the help of GIS web application Radiance Light Trends and the light trends analysis tool. The application allows examination of changes in light pollution across selected areas since 1992 and performs time-series analysis with fitting an exponential curve into the data set. Results. The trend in light emissions observed by satellites for Chernivtsi Region indicated brightening at the rate of 2.45 % per year from 1992 to 2014, and 2.93 % per year from 2014 to 2021. The marked increase in the intensity of atmospheric light pollution over Chernivtsi Region is largely attributable to urban expansion of district centers, national & international routes and resort complexes. At the same time, the spatial pattern of the light environment over city of Chernivtsi indicated a nearly constant level of aggregate annual light radiance for the last 8 years. A large irregularly shaped "light spot" was detected on the territory of the Prut-Siret interfluve. It crosses the region from the northwest to the southeast and covers the regional center with its suburbs and the national highway H-10. The night light radiance constitutes 47.49∙10-9 mW/cm2 sr in the center of the spot and more than 1∙10-9 mW/cm2 sr at its edges. The highest level of light pollution in Chernivtsi Region was registered in January, and the lowest – in March. Night-time light emission over two most illuminated highways remains relatively constant regardless of the season. Conclusion. The study highlights that despite low population and low economic activity, rural landscapes demonstrate a trend towards increasing brightness of the night sky. The findings provide a quantitative reference for light pollution management in the region and for further research in the area. 

scholarly journals ANALYSIS OF APPLICATION OF CONTEMPORARY NIGHT VISION GOGGLES ON THE BASIS OF ELECTRONIC-OPTICAL CONVERTER BY THE HELICOPTER CREWS. PROSPECTIVE HELICOPTER OPTOELECTRONIC SYSTEMS OF AERIAL RECONNAISSANCE/SURVEILLANCE

2020 ◽  
pp. 50-55
Author(s):  
O. Kuzmich ◽  
V. Kuznetsov ◽  
M. Andrushko
Keyword(s):  
Search And Rescue ◽  
Night Vision ◽  
Target Acquisition ◽  
Optoelectronic System ◽  
Night Time ◽  
Low Light ◽  
Spectral Bands ◽  
Light Levels ◽  
Aerial Reconnaissance ◽  
Optoelectronic Systems

The paper studies the matters of using of night vision goggles by the helicopter crews of the State Aviation of Ukraine. The analysis of the perspective systems that can replace night vision goggles based on electronic-optical converter and provide round-the-clock and all-weather flights, landing of the helicopter on unprepared and unlit areas in poor visibility was treated. Currently, the practice of using combat and transport helicopters involves their wider use in the night-time conditions (air warfare, delivery of goods, search-and-rescue operations). Due to low light levels, until recently, most night-time target acquisition tasks have been related with the necessities of providing the artificial target illumination, but in certain instances such illumination deteriorates visibility through an lighttight, phosphorescent atmospheric shells or it just can‟t be carried out. The need for a large number of channels included in the optoelectronic system, caused by the variety of tasks that are solved by it, as well as the imperfection of each individual channel. This forces them to be combined to improve the efficiency of the optoelectronic systems themselves, so that the disadvantages of one channel are offset by the advantages of another. In fact, it is only possible way to ensure the fulfilment of combat task by combining channels operating in different spectral bands in one scheme and by combining detection devices. It can be stated that, despite the undisputed advantages of optoelectronic systems as compared to night-vision goggles, in case of the selecting for installing on a helicopter of optoelectronic systems, it should take into account the much higher cost of optoelectronic systems compared with night-vision goggles. Therefore, the rationale for installing optoelectronic systems must be determined based on the scope of the executing tasks, which are to be conducted by a specific helicopter.

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