Effect Of Ambient Light Research Articles

A Novel Gaze Input System Based on Iris Tracking With Webcam Mounted Eyeglasses

AbstractDue to the high cost of eye-tracking systems based on pupillary corneal reflections, efforts to develop a webcam-based eye-tracking system have increased to provide an affordable alternative to disabled people in recent years. However, due to the camera specification and location, ambient light changes and positional changes of the users, the gazing point of the eyes has not yet been determined precisely by such a system. Therefore, only 8 different gaze directions or up to 10 gaze regions could be detected in the previous webcam-based human–computer interaction studies. In this study, a novel gaze input system has been proposed to make the best use of the limited performance of webcam-based eye tracking and offer an economical alternative for disabled people. To reduce the impact of head movements, the webcam has been mounted to an ordinary glasses frame and positioned in front of the eye. For estimation of the gaze regions, a feature-based method (Hough transformation) was used by considering the circular shape of the iris and the contrast between the iris and sclera. The central coordinates of the iris image captured by the webcam were given to the k-nearest neighbor classifier. We performed a series of experiments with 20 subjects to determine the performance of the system and to investigate the effect of ambient light on the system’s accuracy. The 23 regions that were gazed at by subjects were determined with an average accuracy of 99.54%. When the ambient light level was reduced by half, the accuracy decreased to 94.74%. As a result, it has been found that the proposed prototype allows more accurate recognition of a larger number of regions on the screen than previous webcam-based systems. It has been observed that system performance decreases if the ambient light is reduced byhalf.

The Display Week 2021 Symposium Preview

The Display Week 2021 Symposium Preview

Effect of ambient lighting conditions on tooth color quantification in cross-polarized dental photography: A clinical study

Statement of problemLimited data are available in the dental literature regarding the effect of ambient lighting on the consistency of color quantification in cross-polarized photography. PurposeThe purpose of this clinical study was to investigate the effects of ambient lighting conditions and postprocessing photograph calibration on color quantification in cross-polarized dental photography. Material and methodsTwelve volunteers with intact maxillary central incisors were recruited. Cross-polarized photographs were captured under light-emitting diode (LED), fluorescent ceiling, and natural lighting. The photographs were repeated after a 1-week interval, yielding a total of 72 photographs. The average Commission Internationale de l’Eclairage L∗a∗b∗ coordinates of the right central incisor were obtained with a software program before and after calibration by using a neutral gray reference card. The color difference (ΔE) values were calculated for each participant between the repeated photographs under the change and no change in illumination both before and after calibration. A 3-way repeated measures ANOVA was used to compare these values (α=.05). ResultsA statistically significant 3-way interaction was found between the illuminant type, change in illumination, and calibration (P<.001); however, all the ΔE values were within a clinically acceptable threshold (ΔE≤3.7). Before calibration, when photographs were captured under no change in illumination, LED lighting was found to have a significantly lower ΔE than fluorescent (P=.008) and natural and fluorescent lightings (P=.011), but when there was a change in illumination, no significant differences (P>.05) were found. After calibration, all the ΔE values were ≤1 and significantly lower than the values before calibration (P<.001). ConclusionsBoth the ambient illuminant type and change in illumination had minimal effects on ΔE. Calibration through the use of a neutral gray reference card was found to result in reduced and imperceptible color change (ΔE≤1) for all illuminant types.

Phase measuring deflectometry for obtaining 3D shape of specular surface: a review of the state-of-the-art

Phase measuring deflectometry (PMD) is a superior technique to obtain three-dimensional (3D) shape information of specular surfaces because of its advantages of large dynamic range, noncontact operation, full-field measurement, fast acquisition, high precision, and automatic data processing. We review the recent advances on PMD. The basic principle of PMD is introduced following several PMD methods based on fringe reflection. First, a direct PMD (DPMD) method is reviewed for measuring 3D shape of specular objects having discontinuous surfaces. The DPMD method builds the direct relationship between phase and depth data, without gradient integration procedure. Second, an infrared PMD (IR-PMD) method is reviewed to measure specular objects. Because IR light is used as a light source, the IR-PMD method is insensitive to the effect of ambient light on the measured results and has high measurement accuracy. Third, a proposed method is reviewed to measure the 3D shape of partial reflective objects having discontinuous surfaces by combining fringe projection profilometry and DPMD. Then, the effects of error sources that mainly include phase error and geometric calibration error on the measurement results are analyzed, and the performance of the 3D shape measurement system is also evaluated. Finally, the future research directions of PMD are discussed.

The Effect of Ambient Lighting on the Preferred Color Temperature of Television

In this study, the preferred correlated color temperature (CCT) of the television was evaluated according to the CCT change of lighting. In the experiment, the laboratory was set up by considering five ambient lighting CCT conditions between 2500K and 6300K. In each environment, the CCT of the TV was changed from 4000K to 11500K, and an experiment was conducted to select the most preferred TV CCT. In general, it was preferred when the CCT of the TV was changed considering the CCT of the ambient light, compared to the viewing environment in which the TV was watched in one environment regardless of the CCT of the ambient light. If the CCT of the light decreases, the CCT of the display should also be lowered. Especially in low-color lighting environments, such as incandescent lights, when the TV's CCT is lowered, the white part of the image appears to be ‘real’ white and the images were more preferred.

Light, flight and the night: effect of ambient light and moon phase on flight activity of pteropodid bats.

Fruit-feeding pteropodid bats roost under varying light conditions. Some roost in trees with high exposure to daylight (> 1000lx), while others roost in dark caves (< 0.1lx). To understand the effect of ambient light intensity and moon phase on flight activity, we examined flight times across five lunar cycles in three pteropodid species whose roosts differ in daylight exposure. We found significant interspecific differences in flight emergence and termination times. All species initiated flights after sunset but Rousettus leschenaultii, which typically roosts in caves, delayed emergence (40 ± 11min) more than the two tree-roosting species Pteropus giganteus (16 ± 6min) and Cynopterus sphinx (19 ± 7min). R. leschenaultii terminated flights earlier (30 ± 7min before sunrise) than P. giganteus (11 ± 11min) and C. sphinx (16 ± 10min). All individuals from P. giganteus and C. sphinx roosts emerged within less than an hour, while emergence times were more spread out in the R. leschenaultii colony. Peak emergence times differed across moon phases in the cave-roosting R. leschenaultii but not in the other species. Flight activity in R. leschenaultii is restricted to comparatively lower light levels than the tree-roosting species. The observed interspecific differences suggest that bat species, sharing same landscapes may respond differently to light pollution.

Effects of Ambient Bright Light on Neurobehavioral Symptoms in Dementia: A Systematic Review

Most persons living with dementia (PLwD) experience behavioral and psychological symptoms of distress in dementia (BPSDs). Despite increased utilization of bright light to improve BPSDs, the evidence of effectiveness and dosage using ambient light has not been comprehensively examined. This review synthesized research evidence on the effect of ambient light on BPSD in PLwD. A literature search conducted in Scopus, PubMed, CINAHL, and Web of Science included keywords: dementia, bright light, ambient light, indirect light, behavior symptoms, agitation, wandering, depression, aggression, and apathy. Original studies that examined the effect of ambient light on BPSDs were included. Six studies were identified. Sample size ranged from 6 to 189. Lighting delivery methods included a lighting table and ceiling-mounted fixtures in public areas and/or participant’s bedroom. Lighting intensity ranged from 1,000-3,000 lux, color temperature ranged from bluish white to warm white, and exposure duration ranged from 4 to 24 hours a day. PLwD with higher light exposure showed more pleasure and alertness. Ambient bright lighting showed mixed results in reducing agitation with one study reporting increased agitation. Three out of four studies showed positive effects upon depressive symptoms. Ambient bright light positively impacted pleasure and alertness. Mixed results on agitation and depressive symptoms may be explained by differences in illuminance, color, duration, and targeted lighting positions. Further studies are needed to confirm the positive effects of ambient light on BPSD. Accurate lighting exposure measurements related to spectral compositions and dosage for individual PLwD would help explain the underlying relationships between lighting and BPSD.

Minimising ambient illumination via ambient subtraction: smartphone assessment of jaundice in liver patients via sclera images

Using smartphone images to quantify color presents a noninvasive way to assess jaundice and other color-related biomarkers of the human body. Here we focus on assessing jaundice through accurate bilirubin measurement in adult liver patients, the first time optical imaging has been applied to this cohort. These patients can suffer from very high levels of bilirubin, indicating their severity of liver disease. A smartphone assessment technique for jaundice based around the color of the sclera (white of the eye) extracted from images is being developed, as smartphone imaging enables cheap, non-invasive and quantitative readings. Variations in ambient light cause large changes to recorded pixel values so must be accounted for to ensure that any changes detected are due to changes in jaundice level. Here we suggest the use of an ambient subtraction approach to minimise the effects of ambient light. Pairs of flash/ no-flash images are captured and the extracted values subtracted to yield data as though under a pure flash illumination. We present data demonstrating the technique with a group of healthy adult volunteers. We also present data from a patient study involving adults with liver disease. Images were captured and the bilirubin (jaundice) level predicted from these images before and after subtraction was compared to the ground truth value obtained via blood test. The linear correlation coefficient increased from 0.47 to 0.85 (p &lt; 0.001 in both cases) upon application of subtraction, demonstrating the effectiveness of the technique.

Fourier domain diffuse correlation spectroscopy with heterodyne holographic detection.

We present a new approach to diffuse correlation spectroscopy which overcomes the limited light throughput of single-mode photon counting techniques. Our system employs heterodyne holographic detection to allow parallel measurement of the power spectrum of a fluctuating electric field across thousands of modes, at the shot noise limit, using a conventional sCMOS camera. This yields an order of magnitude reduction in detector cost compared to conventional techniques, whilst also providing robustness to the effects of ambient light and an improved signal-to-noise ratio during in vitro experiments. We demonstrate a GPU-accelerated holographic demodulation system capable of processing the incoming data (79.4 M pixels per second) in real-time, and a novel Fourier domain model of diffuse correlation spectroscopy which permits the direct recovery of flow parameters from the measured data. Our detection and modelling strategy are rigorously validated by modulating the Brownian component of an optical tissue phantom, demonstrating absolute measurements of the Brownian diffusion coefficient in excellent agreement with conventional methods. We further demonstrate the feasibility of our system through in vivo measurement of pulsatile flow rates measured in the human forearm.

On the Ambient Optic Array: James Gibson's Insights About the Phenomenon of Chiaroscuro.

In 1966, James Gibson first presented his theory of the ambient optic array, and he proposed a new field of ecological optics that he hoped would advance our knowledge on this topic. This study will consider how his ideas have largely come to fruition over the past 50 years. It reviews the research on the visual perception of three-dimensional shape from shading, the effects of ambient light from surface interreflections on observers’ perceptions, the perception of the light field, and the perception of surface materials. Finally, it also considers Gibson’s impact on these developments.

Motorcycle safety after-dark: The factors associated with greater risk of road-traffic collisions

The effect of ambient light level on road traffic collisions (RTCs) involving a motorcycle was investigated. Data were drawn from the STATS19 database of UK reported RTCs for the period 2005–2015. To isolate the effect of ambient light (daylight vs darkness) an odds ratio was used to compare RTCs at specific times of day in the weeks either side of the Spring and Autumn clock changes. This work extended previous studies by using a more precise method for distinguishing between RTCs in daylight and after dark, thus avoiding the ambiguity of twilight. Data for four-wheel motor vehicle (FWMV) RTCs were also investigated to provide a datum. As expected, the risk of an RTC occurring was significantly higher after dark compared to daylight for both motorcycles and FWMVs. Investigation of contextual factors suggests that risk after dark is significantly higher for motorcycles compared to FWMVs for RTCs with two-vehicles, on roads with low speed limits (≤30 mph), at T-junctions, and junctions controlled by a give way sign. These are the situations where visual aids for increasing conspicuity after dark have the greater potential for reducing motorcycle RTCs.

Effects of low intensity ambient lighting on refractive development in infant rhesus monkeys (Macaca mulatta)

Studies in chickens suggest low intensity ambient lighting causes myopia. The purpose of this experiment was to examine the effects of low intensity ambient lighting (dim light) on normal refractive development in macaque monkeys. Seven infant rhesus monkeys were reared under dim light (room illumination level: ~55 lx) from 24 to ~310 days of age with otherwise unrestricted vision. Refractive error, corneal power, ocular axial dimensions, and choroidal thickness were measured in anesthetized animals at the onset of the experiment and periodically throughout the dim-light-rearing period, and were compared with those of normal-light-reared monkeys. We found that dim light did not produce myopia; instead, dim-light monkeys were hyperopic relative to normal-light monkeys (median refractive errors at ~155 days, OD: +3.13 D vs. +2.31 D; OS: +3.31D vs. +2.44 D; at ~310 days, OD: +2.75D vs. +1.78D, OS: +3.00D vs. +1.75D). In addition, dim-light rearing caused sustained thickening in the choroid, but it did not alter corneal power development, nor did it change the axial nature of the refractive errors. These results showed that, for rhesus monkeys and possibly other primates, low ambient lighting by itself is not necessarily myopiagenic, but might compromise the efficiency of emmetropization.

The interacting effects of total light intensity and chromatic contrast on visual signal visibility in an Anolis lizard

The sensory drive hypothesis states that selection acts on signals to make them more detectable in the habitat conditions in which they occur, resulting in signal divergence for species occupying different habitats. For colour signals, visibility depends on the luminance contrast and the chromatic contrast between the signal and the viewing background. Sensory drive has been tested in studies of the colourful dewlaps of anolines occupying different habitats. These studies found that red or orange dewlaps were more visible than yellow or white dewlaps across all habitat types, counter to the predictions of sensory drive that a species’ signal should be more visible in its own habitat than in habitats of other species. However, in these, and other sensory drive studies, chromatic contrast was calculated with a visual perception model that assumed that total light intensity has little or no effect on chromatic contrast perception. We carried out behavioural experiments testing the probability of detection of green, yellow and red stimuli presented against luminance-matched green backgrounds, at low and high light intensity typical of shaded and unshaded habitats. We found that the red stimulus was most detectable in the high light condition, while in low light, yellow and red stimuli were equally detectable. We modelled the stimuli with a receptor noise model that takes total light intensity into account. The model predictions were consistent with the behaviour results. We conclude that there is an important interaction between total light intensity and chromatic contrast in determining the visibility of colour signals, which should be taken into account in visual ecology studies. For animals with small eyes, shade level, which strongly influences total light intensity, may be as important as, or more important than habitat spectral quality in the evolution of signal colour diversity through sensory drive. • Anolis lizards signal with red and yellow throat fans. • We tested effects of ambient light on signal visibility against a green background. • In high light, typical of low shade, red is most visible. • In low light, typical of shaded habitat, yellow and red are equally visible. • Habitat shade level may drive the evolution of Anolis signal colour differences.

Relationship between Indoor Daytime Light Exposure and Circadian Phase Response under Laboratory Free-Living Conditions

ABSTRACT In this study, we measured the physical quantity of light (irradiance) in several wavelength bands at eye and wrist level for 8 h under laboratory conditions simulating daily life. Twenty-two healthy male participants (mean age ± SD, 29.95 ± 8.13 years) were able to move freely, and eye-level data were compared with irradiance data obtained at the wrist. We estimated circadian phase shift from the differences of DLMO before and after light exposure while considering natural drift. In addition, we investigated the influence of activities and body positions on light exposure and validated the effect of irradiance on circadian phase response. We found lower average irradiance at eye level compared with wrist level in all three RGB bands. The blue light irradiance measured at eye level was significantly correlated with circadian phase shift, possibly because the irradiance at eye level more accurately reflected its effect on the biological clock than did the measurement at the wrist. It follows that quantitative measurements of wavelength spectra at eye level are necessary to assess the effect of ambient light on the human biological clock.

Optical Pixel Sensor Based on a-Si:H TFTs to Detect Combined Optical Signals for Multiuser Interactive Displays

This article presents new optical pixel sensors that are based on hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) for detecting secondary color optical signals to increase the number of colors of sensed light. Three types of series-connected structure with different photo TFTs enable the sensors to receive secondary color optical input signals that combine any two primary colors, such as magenta (blue and red), cyan (green and blue), and yellow (red and green). The secondary color optical sensors also prevent from being affected by light of a single color to integrate with primary color optical sensors for realizing a six-color sensing mechanism. Moreover, only one photo TFT is used to suppress the effect of ambient white light by compensating photocurrents without increasing the complexity of the proposed sensor structure. The measurements demonstrate that the difference in the output voltages is 15.6 V even under ambient white light with an intensity of 10000 lux, proving that the proposed sensor can yield significantly different sensing results with and without an optical input signal under intense ambient white light. Thus, the proposed sensors increase the number of sensed color light that can be integrated with a large TFT-LCD panel for multiuser interaction.

Ambient light robust gamut mapping for optical see-through displays.

An optical see-through (OST) display is affected more severely by ambient light than any other type of displays when placed in an outdoor environment with bright illuminance because of its transparency and thus, its inherent color distortion can worsen. It is hard to directly apply existing gamut mapping methods to an OST display because of its morphological gamut characteristic and the effect of ambient light. In this paper, we propose a new robust gamut mapping method which works against bright ambient light. The process is divided into two steps: lightness mapping (LM) and chroma reproduction. LM aligns the lightness level of sRGB gamut with OST gamut and partitions the region of OST gamut based on the relative size of the sRGB gamut and its lightness value. The second step (chroma reproduction) determines an appropriate chroma reproduction method (gamut compression or extension) and a proper direction for gamut mapping based on the characteristics of each region in order to minimize the effects of ambient light. The quality of color reproduction is qualitatively and quantitatively evaluated based on accurate measurements of the displayed colors. It has been experimentally confirmed that the proposed gamut mapping method can reduce color distortion more than the existing parametric gamut mapping algorithms.

Analysis on the Optical Response of Ldr and Phototransistor in Photoplethysmography

In photoplethysmography, light source and light detector are employed such that the received signal corresponds to a particular information needed. This research used five different LEDs as light sources. Phototransistor and LDR, on the other hand, were used as light detectors to assess the photosensitivity of human skin. Backscatter simulation was used to compare the photoplethysmographic detection of LDR and phototransistor. The aims of this study include: determine the optical response of a human skin, particularly the skin on the dorsal and palmar parts of the hand; conduct simultaneous simulation using modular and backscattered setup; provide measured value based on the conducted simulations. In every LED color and for both light detectors, ten test conditions were performed, namely: (1) room light on; (2) room light off; (3) room light on - black paper; (4) room light off - black paper; (5) room light on - white paper; (6) room light off – white paper; (7) room light on – dorsal skin; (8) room light off – dorsal skin; (9) room light on – palmar skin; and (10) room light off – palmar skin. Two different simulations were conducted involving all test conditions. The second simulation used light meter which showed similarity in behaviour of obtained values vis-à-vis barcode meter and ADC voltage. The modular involved a lux sensor which checked the findings on the reflectivity of skin Types III and IV of the Fitzpatrick scale and melanocytic naevi skin. The series of simulations conducted proved that the yellow LED provided highest sensor response and phototransistor greater sensitivity than LDR in detecting the received signals. Room light off condition was necessary to reduce the effects of ambient light.

The Effects of High Lighting on the Development of Form-Deprivation Myopia in Guinea Pigs.

To investigate the effects of high ambient lighting on refraction and ocular biometry in guinea pig models of form-deprivation myopia (FDM). Forty 3-week-old guinea pigs were randomly assigned to groups exposed to either high light (HL, 10,000 lux) or normal light (NL, 500 lux) with normal vision or form deprivation. Throughout the 10-week rearing period, animals were exposed to high light or normal light for 12 hours with a 12-hour light/dark cycle. Refraction, axial length (AL), and radius of corneal curvature (CCR) were measured by cycloplegic retinoscopy, A-scan ultrasonography, and keratometer, respectively. At the end of treatment, form-deprived eyes under high ambient lighting exhibited more hyperopic refraction and shorter AL than those under normal ambient lighting (2.06 ± 1.68 diopters [D; mean ± SD] vs. -0.59 ± 1.56 D, P < 0.001; 8.36 ± 0.13 mm vs. 8.56 ± 0.16 mm, P < 0.001). Deprived eyes under high ambient lighting were relatively more myopic than their contralateral control eyes at the end of treatment (2.06 ± 1.68 D vs. 5.44 ± 0.66 D, P < 0.001). High lighting induced a significant hyperopic shift in normal eyes after 4 weeks of exposure. There were no significant differences in CCR between eyes exposed to high and normal light, nor between deprived eyes and contralateral eyes. High ambient lighting could retard, but not fully inhibit, the development of FDM. High light levels contributed to a greater hyperopic shift in normal eyes during the first 4 weeks of treatment. Corneal curvature was unaffected by either high ambient lighting or form deprivation.

124 Investigating the Impact of Ambient Lighting on Adenoma Detection Rate and Eye Fatigue During Screening Colonoscopy

INTRODUCTION: Previous studies indicate that adenoma detection rate (ADR) decreases as the number of consecutive hours performing procedures increases. Differences in adaptation between a bright screen and a dimly lit room may contribute to eye strain and eye strain related symptoms occur in most video display users. Increasing ambient light may improve symptoms of eye strain, but ambient light effects have yet to be explored in the field of gastroenterology. We aim to determine if the use of ambient lighting, between 75–150 lux, during screening colonoscopy will maintain ADRs and decrease symptoms of eye strain. METHODS: A single center study comparing screening colonoscopies in a dimly lit room to use of ambient lighting by 9 gastroenterologists was performed. Retrospective data was collected over a 6-month period performed in procedure rooms with no lighting. Prospective data was then collected on colonoscopies with ambient lighting during the same 6 calendar months the following year. A survey on eye fatigue was completed by all gastroenterologists before and after the use of ambient lighting. Satisfaction surveys were completed by gastroenterologists, anesthesiologists, nurses and technicians. RESULTS: There were 498 low light and 611 ambient light cases. 172 adenomas (ADR = 34.5%) were detected with low light and 220 adenomas were detected with ambient light (ADR = 36.0%) (P = 0.611). For low light cases, ADR was 37.5% for 1st cases of the day and 31.9% for last cases of the day (P = 0.545) (Table 1). For ambient light cases, the ADR was 34.1% for 1st cases of the day and 36.9% for last cases of the day (P = 0.266). Overall difference in ADR between 1st and last cases using ambient lighting (+2.80%) versus no lighting (−5.60%), was statistically significant (P = 0.010) (Table 2). 41% of respondents agreed or strongly agreed fewer symptoms of eyes strain occurred with ambient light and 54% of respondents felt that ambient light improved detection of changes in patient status. CONCLUSION: Our data suggests that performing screening colonoscopies with ambient light may improve the differential change in ADR that occurs from the beginning to the end of the day, as compared with lights off. This improvement in ADR may be related to improved symptoms of eye strain, and further investigation is warranted.

오토인코더를 이용한파랑 비디오 영상에서의 수리동역학적 장면 분리 연구

In this paper, we propose a hydrodynamic scene separation method for wave propagation from video imagery using autoencoder. In the coastal area, image analysis methods such as particle tracking and optical flow with video imagery are usually applied to measure ocean waves owing to some difficulties of direct wave observation using sensors. However, external factors such as ambient light and weather conditions considerably hamper accurate wave analysis in coastal video imagery. The proposed method extracts hydrodynamic scenes by separating only the wave motions through minimizing the effect of ambient light during wave propagation. We have visually confirmed that the separation of hydrodynamic scenes is reasonably well extracted from the ambient light and backgrounds in the two videos datasets acquired from real beach and wave flume experiments. In addition, the latent representation of the original video imagery obtained through the latent representation learning by the variational autoencoder was dominantly determined by ambient light and backgrounds, while the hydrodynamic scenes of wave propagation independently expressed well regardless of the external factors.