scholarly journals Measuring Facial Illuminance with Smartphones and Mobile Devices

2021 ◽  
Vol 11 (16) ◽  
pp. 7566
Author(s):  
Rosa María Salmerón-Campillo ◽  
Arthur Bradley ◽  
Mateusz Jaskulski ◽  
Norberto López-Gil
Keyword(s):  
Light Exposure ◽  
Light Sources ◽  
Ambient Light ◽  
Myopia Progression ◽  
Full Field ◽  
High Linearity ◽  
Light Sensor ◽  
Environmental Light ◽  
The Face ◽  
Office Lighting

Introduction: To uncover a relationship between light exposure and myopia is complicated because of the challenging nature of measuring visually relevant illumination experienced by children. Objective: To find a methodology to measure face illuminance using a mobile device. Methods: Accuracy and precision of the mobile device’s built-in ambient light sensor were tested under three different lighting conditions: full-field, a single small light, and one mimicking typical office illumination. Face illuminance was computed in six faces with different skin reflectances using pixel values in face images captured by the device camera placed at 30 cm in front of the face. The results were compared with those obtained with a commercial light meter situated at the face. Results: The illuminance measured by the device’s ambient light sensor showed high linearity (R2 > 0.99) slightly under-estimating or conversely over-estimating face illuminance with full-field or single light sources but accurate for office lighting. Face illuminance measured by the devices’ camera under indoor conditions using the new methodology showed a mean relative error of 27% and a high linearity (R2 > 0.94). Conclusions: Introduction of an app can be used to assess the association between visually relevant environmental light levels and myopia progression.

scholarly journals Invalidity of light sensor data in field studies and a proposal of an algorithmic approach for detection and filtering of non-wear time

2021 ◽  
Author(s):  
Larissa C Hunt ◽  
Josef Fritz ◽  
Michael Herf ◽  
Céline Vetter
Keyword(s):  
Light Exposure ◽  
Area Under The Curve ◽  
Field Studies ◽  
Population Based ◽  
Light Signal ◽  
Sensor Data ◽  
Youden Index ◽  
Wear Time ◽  
Light Sensor ◽  
Environmental Light

Wearable light sensors are increasingly used in intervention and population-based studies investigating the consequences of environmental light exposure on human physiology. An important step in such analyses is the reliable detection of non-wear time. We observed in light data that days with less wear-time also have lower variability in the light signal, and we sought to test if the standard deviation of the change between subsequent samples can detect this condition. In this study, we propose and validate an easy-to-implement algorithm designed to discriminate between days with a non-wear time >4h ('invalid days') vs. ≤4h ('valid days') and investigate to which extent values of commonly used physiologically meaningful light variables differ between invalid days, valid days, and algorithm-selected non-wear days. We used 83 days of light data from a field study with high participant compliance, complemented by 47 days of light data where free-living individuals were instructed not to wear the sensor for varying amounts of time. Light data were recorded every two minutes using the pendant-worn f.luxometer light sensor; validity was derived from daily logs where participants recorded all non wear time. The algorithm-derived score discriminated well between valid and invalid days (area under the curve (AUC): 0.77, 95% CI: 0.67-0.87). The best cut-off value (i.e., highest Youden index) correctly recognized valid days with a probability of 87% ('sensitivity'), and invalid days with a probability of 63% ('specificity'). Values of various light variables derived from algorithm selected days only (median: 264.3 (Q1: 153.6, Q3: 420.0) for 24h light intensity (in lux); 496.0 (404.0, 582.0) for time spent above 50-lux) gave values close to those derived from self reported valid days only. However, these values did not significantly differ when derived across all days compared to self-reported valid days. Our results suggest that our proposed algorithm discriminates well between valid and invalid days. However, in high compliance cohorts, distortions in aggregated light measures of individual-level environmental light recordings across days appear to be small, making the application of our algorithm optional, but not necessary.

scholarly journals Daily indoor light exposure: A spectral analysis of ambient light sources and its relevance to occupational dermatology

2017 ◽  
Vol 76 (4) ◽  
pp. 763-765 ◽  
Author(s):  
Teo Soleymani ◽  
Lorcan M. Folan ◽  
Nicholas A. Soter ◽  
Nada Elbuluk ◽  
David E. Cohen
Keyword(s):  
Spectral Analysis ◽  
Light Exposure ◽  
Light Sources ◽  
Ambient Light ◽  
Occupational Dermatology

scholarly journals Preliminary study of simple methods to get the average speed using a smartphone's light sensor

2018 ◽  
Vol 197 ◽  
pp. 02003 ◽  
Author(s):  
Ea Cahya Septia Mahen ◽  
Seni Susanti ◽  
Bebeh Wahid Nuryadin ◽  
Ade Yeti Nuryantini
Keyword(s):  
Light Sources ◽  
Ambient Light ◽  
Position Information ◽  
Average Speed ◽  
Light Sensor ◽  
Straight Line ◽  
Android Applications ◽  
Preliminary Study ◽  
Physics Experiments

This paper reports on the result of a preliminary study of utilization of a smartphone ambient light sensor for get the average speeds of motion along a straight line based on experiments. We attach a smartphone to a dynamics train that travels across multiple light sources where the distance is already set. The main source of this experiment is obtained from the luminosity curve obtained from free android applications. From the curve, we can get position information against time. So from the data we can get the value of average speed. Then the use of the smartphone light sensor in physics experiments can be done easily and fun.

scholarly journals Characterization of linear light sources with the smartphone’s ambient light sensor

2018 ◽  
Vol 56 (8) ◽  
pp. 562-563 ◽  
Author(s):  
Isabel Salinas ◽  
Marcos H. Giménez ◽  
Juan A. Monsoriu ◽  
Juan C. Castro-Palacio
Keyword(s):  
Light Sources ◽  
Ambient Light ◽  
Light Sensor

Integrated Ambient Light Sensor with an LTPS Noise-Robust Circuit and a-Si Photodiodes for AMLCDs

2010 ◽  
Vol E93-C (11) ◽  
pp. 1583-1589
Author(s):  
Fumirou MATSUKI ◽  
Kazuyuki HASHIMOTO ◽  
Keiichi SANO ◽  
Fu-Yuan HSUEH ◽  
Ramesh KAKKAD ◽  
...  
Keyword(s):  
Ambient Light ◽  
Light Sensor ◽  
Noise Robust

An LTPS Ambient Light Sensor System with Sensitivity Correction Methods in LCD

2019 ◽  
Vol E102.C (7) ◽  
pp. 558-564
Author(s):  
Takashi NAKAMURA ◽  
Masahiro TADA ◽  
Hiroyuki KIMURA
Keyword(s):  
Sensor System ◽  
Ambient Light ◽  
Light Sensor

Research on Improved Gamma Transform Face Image Preprocessing Fusion Algorithm under Complex Lighting Conditions

2020 ◽  
Vol 13 ◽  
Author(s):  
Xiaolin Tang ◽  
Xiaogang Wang ◽  
Jin Hou ◽  
Huafeng Wu ◽  
Ping He
Keyword(s):  
Edge Detection ◽  
Face Image ◽  
Light Sources ◽  
Fusion Algorithm ◽  
Edge Information ◽  
Image Preprocessing ◽  
Lighting Conditions ◽  
Weighted Fusion ◽  
The Face ◽  
Sobel Edge Detection

Introduction: Under complex illumination conditions such as poor light sources and light changes rapidly, there are two disadvantages of current gamma transform in preprocessing face image: one is that the parameters of transformation need to be set based on experience; the other is the details of the transformed image are not obvious enough. Objective: Improve the current gamma transform. Methods: This paper proposes a weighted fusion algorithm of adaptive gamma transform and edge feature extraction. First, this paper proposes an adaptive gamma transform algorithm for face image preprocessing, that is, the parameter of transformation generated by calculation according to the specific gray value of the input face image. Secondly, this paper uses Sobel edge detection operator to extract the edge information of the transformed image to get the edge detection image. Finally, this paper uses the adaptively transformed image and the edge detection image to obtain the final processing result through a weighted fusion algorithm. Results: The contrast of the face image after preprocessing is appropriate, and the details of the image are obvious. Conclusion: The method proposed in this paper can enhance the face image while retaining more face details, without human-computer interaction, and has lower computational complexity degree.

scholarly journals The Environmental Light Influences the Circulatory Levels of Retinoic Acid and Associates with Hepatic Lipid Metabolism

Endocrinology ◽  
2008 ◽  
Vol 149 (12) ◽  
pp. 6336-6342 ◽  
Author(s):  
Wenqiang Pang ◽  
Chunying Li ◽  
Yue Zhao ◽  
Shiming Wang ◽  
Wei Dong ◽  
...  
Keyword(s):  
Gene Expression ◽  
Retinoic Acid ◽  
Adenosine Receptors ◽  
Light Exposure ◽  
Retinoic Acid Receptor ◽  
Hepatic Lipase ◽  
Mouse Retina ◽  
Acid Receptor ◽  
Hepatic Lipid ◽  
Environmental Light

Environmental light is involved in the regulation of photochemical reaction in mouse retina. It remains unclear whether light-mediated increase in all-trans retinoic acid (ATRA) synthesis in retina will result in altering the circulatory levels of ATRA and regulating downstream gene expression and physiological function. Here we showed circulatory levels of ATRA decreased in mice under constant darkness and elevated by light exposure. Fat gene pancreatic lipase-related protein 2 (mPlrp2) and its partner procolipase (mClps), but not hepatic lipase (mHl), activated in livers for responding to lack of light illuminating. Light-triggered alterations in circulatory ATRA levels regulated ecto-5′-nucleotidase gene expression by retinoic acid receptor retinoic acid receptor-α and modulated 5′-AMP levels in blood and were associated with mPlrp2 and mClps expression in the livers. Mice deficient in adenosine receptors displayed mPlrp2 and mClps expression in livers under 12-h light, 12-h dark cycles. Caffeine blocked adenosine receptors and induced hepatic mPlrp2 and mClps expression in wild-type mice. Mice activated in hepatic mPlrp2 and mClps expression lowered hepatic and serum lipid levels and markedly elevated circulatory levels of all-trans retinol. Our results suggest environmental light influence hepatic lipid homeostasis by light-modulated retinoic acid signaling associated with mPlrp2 and mClps gene expression in livers.

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