Flash Photography Research Articles

To compare horizontal strabismus deviation as assessed from photographs with that in the strabismus clinic using the prism bar.

To compare the deviation in cases of horizontal strabismus as assessed from photographs with the measurements as obtained in the strabismus clinic. After obtaining informed consent, we recruited subjects with manifest horizontal strabismus. We took a frontal flash photograph from a distance of 50 cm using smart-phone-based cameras with the flash light vertically aligned with the lens. After projecting the photograph on a laptop and using a vernier caliper, we measured the horizontal corneal diameter of the non-strabismic eye and the decentration of reflex in the strabismic eye taking limbus as the reference point. We converted these values to degrees by using a conversion factor of 7.5°/mm and further to prism diopters (PD) by the standard mathematical formula 100*tanθ. We included 74 subjects aged between 5 and 40 years with manifest horizontal deviation from 20 to 85 PD. We found a statistically significant correlation of 82.6% (P value < 0.001) between the clinic and photographic measurements. Agreement analysis suggested that the photographic measurements measured on average 7 PD less (95% confidence interval: 4.6 to 9.2) than clinical measurements along all values of misalignment, although the difference between the two methods decreased as the quantum of deviation increased. Linear regression revealed an r2 of 68% and provided a predictive equation to derive clinic equivalent measurements from photographic estimates. We believe our simple method provides robust evidence that a photographic estimation can provide the basic information of the size of the deviation to plan possible surgeries, especially in situations of a tele-consultation. This is an easy approach to both understand and master and should form the armamentarium of most orthopticians and strabismologists.

High-Fidelity Specular SVBRDF Acquisition From Flash Photographs.

Obtaining accurate SVBRDFs from 2D photographs of shiny, heterogeneous 3D objects is a highly sought-after goal for domains like cultural heritage archiving, where it is critical to document color appearance in high fidelity. In prior work such as the promising framework by Nam et al., the problem is simplified by assuming that specular highlights exhibit symmetry and isotropy about an estimated surface normal. The present work builds on this foundation with several significant modifications. Recognizing the importance of the surface normal as an axis of symmetry, we compare nonlinear optimization for normals with a linear approximation proposed by Nam et al. and find that nonlinear optimization is superior to the linear approximation, while noting that the surface normal estimates generally have a very significant impact on the reconstructed color appearance of the object. We also examine the use of a monotonicity constraint for reflectance and develop a generalization that also enforces continuity and smoothness when optimizing continuous monotonic functions like a microfacet distribution. Finally, we explore the impact of simplifying from an arbitrary 1D basis function to a traditional parametric microfacet distribution (GGX), and we find this to be a reasonable approximation that trades some fidelity for practicality in certain applications. Both representations can be used in existing rendering architectures like game engines or online 3D viewers, while retaining accurate color appearance for fidelity-critical applications like cultural heritage or online sales.

Reliability of a computerized system for strabismus screening.

To evaluate the reliability of Photo-Hirschberg screening for global strabismus performed by non-specialized personnel. Participants at three sites were enrolled. One person at each site was trained in visual acuity measurement and use of the computerized system. Visual acuity was measured, and strabismus testing was performed using two flash photographs. All data from the three primary observers were sent to an experienced assistant researcher, who was blinded to the primary results, for re-evaluation. The primary and re-evaluation results of the Photo-Hirschberg screenings using weighted kappa for agreement were compared. The study included 181 participants (88 males and 93 females) and the results for primary and re-evaluation screenings were corresponded. Ten participants with contrasting results presented with unclear corneal light reflex. Sensitivity and specificity were 100% [95% confidence interval (CI): 29.0%-100%] and 99.4% (95%CI: 96.6%-100%), respectively, based on the Agresti test of the primary evaluation, considering the re-evaluated classification as true. The computerized system can be used for primary strabismus screening by non-specialized personnel, with 98.8% agreement with specialists. However, it cannot be used as a substitute for professional examination.

:Experimental: American Literature and the Aesthetics of Knowledge

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Shape and Albedo Recovery by Your Phone using Stereoscopic Flash and No-Flash Photography

Shape and Albedo Recovery by Your Phone using Stereoscopic Flash and No-Flash Photography

Development of an Easily Reproducible Cough Simulator With Droplets and Aerosols for Rapidly Testing Novel Personal Protective Equipment.

The current COVID-19 pandemic has produced numerous innovations in personal protective equipment, barrier devices, and infection mitigation strategies, which have not been validated. During high-risk procedures such as airway manipulation, coughs are common and discrete events that may expose healthcare workers to large amounts of viral particles. A simulated cough under controlled circumstances can rapidly test novel devices and protocols and thus aid in their evaluation and the development of implementation guidelines. Physiologic cough simulators exist but require significant expertise and specialized equipment not available to most clinicians. Using components commonly found in healthcare settings, a cough simulator was designed for clinicians to easily assemble and use. Both droplet and aerosol particle generators were incorporated into a bimodal experimental system. High-speed flash photography was used for data collection. Using a gas flow analyzer, video recordings, and high-speed digital photography, the cough and particle simulators were quantitatively and qualitatively compared with known physiologic cough parameters and in vivo Schlieren imaging of human coughs. Based on our validation studies, this cough and particle simulator model approximates a physiologic, human cough in the context of testing personal protective equipment, barrier devices, and infection prevention measures.

Sphere Falling Onto A Liquid Jet

Abstract The history of interfacial fluid dynamics is intertwined with the origins of flash photography from the 'Worthington Jet' of Aurthur Worthington [1] to the 'Milk drop coronets' of Harold Edgerton[2] , with this technique capturing ephemeral fluid impacts in their awe-inspiring beauty. Although camera technology has come far from the days of giant flash bulbs, this elegant technique still provides a uniquely focused window into the fleeting impact events that often seem chaotic in real time, but in the suspended reality of flash-photography are found to be surprisingly well patterned. We apply a similar technique with the help of a laser-controlled photo-receptor in a dark room at night with flashes going off when the light received by the photo-receptor is disturbed. The resultant sequential images of Figure 1 are achieved by the timed release of a 50 mm diameter steel sphere falling from 750 mm plunging through an upward moving Worthington Jet that was created by a 38 mm sphere dropped from 230 mm in line with the second sphere. The jet envelopes the sphere from all sides, with thin water films hugging and moving across the sphere surface continuously until they meet at the sphere apex creating beautiful fluid sheets and ligaments in Figure 2. This image not only captures the beauty of the impact but also reveals a novel mechanism of reducing the impact impulse force of falling objects. The sphere in this particular case experiences an almost 70% reduction in impact force compared to a quiescent pool impact [3, 4].

Intent to Change Sun-Protective Behaviors Among Hispanic People After a UV Photoaging Intervention: Cohort Study.

Mortality rates from melanoma are higher among Hispanic populations than non-Hispanic White (NHW) populations. Interventions to improve sun safety are needed. The Reveal Imager is a camera that uses standard cross-polarized flash photography to record surface and subsurface skin conditions. This study aims to determine the intervention's effectiveness in increasing awareness of sun damage and exposure reduction between Hispanic and NHW populations. A cohort of 322 participants, aged ≥18 years, were recruited from community events in 2018. Baseline information was collected on demographics, sun exposure, and perception of risk factors. A facial image was then captured using the Reveal Imager. The results were explained and counseling on sun safety was given, followed by filling out an immediate postimage survey. Chi-square tests, analysis of variance, Wilcoxon signed-rank test, McNemar tests, and multivariable logistic regression were used. At follow-up, 125 of 141 (89%) Hispanic participants reported that viewing the UV photoaged image influenced intent-to-change sun protection behaviors, compared to 88 of 121 (73%) NHW participants (odds ratio 2.9, 95% CI 1.5-5.6). Of 141 Hispanic participants, 96 (68%) reported that they intended to increase sunscreen use, compared to only 41 of 121 (34%) NHW participants (P<.001). We demonstrated an application of Reveal Imager for education and risk assessment. The Reveal Imager was especially helpful in motivating intention to change sun exposure among Hispanic populations.

Development of Photography Interactive Learning Media at Politeknik Negeri Media Kreatif

The absence of intelligent sight and sound in learning photography at Politeknik Negeri Media Kreatif (Polimedia) is the foundation of this examination. In the conveyance of photography material encountered a few hindrances. One of the primary obstructions is the absence of clear and simple to-work learning media. Polimedia Photography Study Program is the object of exploration. The particular motivation behind this exploration is to foster supporting instruments for photography topic through intuitive learning media identified with photography, and to help understudies and teachers in learning photography so quality learning expanded adequately and learning destinations. This review utilizes the Multimedia Development Life Cycle (MDLC) technique with six phases, specifically: idea, plan, material assortment, gathering, testing, and conveyance. To create an intuitive Learning Media Photography requires 11 sorts of perspectives, to be specific intro &amp; background pages, fundamental photography, structure, openness, aperture &amp; depth of field, Camera Basics, External Flash Photography Basics, Lens Basics, Practical photography, Types of Photography, Photography Techniques. The subsequent intelligent learning media for Photography endures a couple of moments, which utilized for understudies as Photography learning materials

Fluorescence intensities of composite resins on photo images

Recording fluorescence using flash photography, may help reduce time of capture and apply effectively in clinical practice. To test methods for visualizing composite resins fluorescence by direct digital photography. Sixty-four specimen discs (1.5 × 10 mm) were prepared from 8 different composite resin brands. Their CIELAB color coordinates (L*, a*, b*) and fluorescence were measured using a portable colorimeter and a fluorescence spectrophotometer. The mean of three measurements was recorded and then specimens were photographed by a DSLR camera with two different filters (365 nm and 405 nm) mounted on a commercial macro flash. RGB values of all specimens on the photographs were measured by using Photoshop software and converted to CIELab. Data were then analyzed using Kruskal–Wallis and Dunn’s multiple comparisons tests. Correlation and regression analyses were also used to relate fluorescence and color parameters on the photographs at α = 0.05. Fluorescence and color data indicated significant differences among the materials (p < 0.05). L* a* and b* color coordinates from both photographs were highly correlated to fluorescence intensities found by the reference method (r365 − 0.95, r405 − 0.94), while regression analysis indicated a strong linear relationship (R2365 − 0.88, R2405 − 0.89). The study showed that filtered flash photography either by the use of a 365 nm or a 405 nm band pass filter can directly visualize fluorescence of composite resin materials and differences in fluorescence between them.

Match

We present MATch , a method to automatically convert photographs of material samples into production-grade procedural material models. At the core of MATch is a new library DiffMat that provides differentiable building blocks for constructing procedural materials, and automatic translation of large-scale procedural models, with hundreds to thousands of node parameters, into differentiable node graphs. Combining these translated node graphs with a rendering layer yields an end-to-end differentiable pipeline that maps node graph parameters to rendered images. This facilitates the use of gradient-based optimization to estimate the parameters such that the resulting material, when rendered, matches the target image appearance, as quantified by a style transfer loss. In addition, we propose a deep neural feature-based graph selection and parameter initialization method that efficiently scales to a large number of procedural graphs. We evaluate our method on both rendered synthetic materials and real materials captured as flash photographs. We demonstrate that MATch can reconstruct more accurate, general, and complex procedural materials compared to the state-of-the-art. Moreover, by producing a procedural output, we unlock capabilities such as constructing arbitrary-resolution material maps and parametrically editing the material appearance.

Barrier Devices, Intubation, and Aerosol Mitigation Strategies: Personal Protective Equipment in the Time of Coronavirus Disease 2019.

BACKGROUND:Numerous barrier devices have recently been developed and rapidly deployed worldwide in an effort to protect health care workers (HCWs) from exposure to coronavirus disease 2019 (COVID-19) during high-risk procedures. However, only a few studies have examined their impact on the dispersion of droplets and aerosols, which are both thought to be significant contributors to the spread of COVID-19.METHODS:Two commonly used barrier devices, an intubation box and a clear plastic intubation sheet, were evaluated using a physiologically accurate cough simulator. Aerosols were modeled using a commercially available fog machine, and droplets were modeled with fluorescein dye. Both particles were propelled by the cough simulator in a simulated intubation environment. Data were captured by high-speed flash photography, and aerosol and droplet dispersion were assessed qualitatively with and without a barrier in place.RESULTS:Droplet contamination after a simulated cough was seemingly contained by both barrier devices. Simulated aerosol escaped the barriers and flowed toward the head of the bed. During barrier removal, simulated aerosol trapped underneath was released and propelled toward the HCW at the head of the bed. Usage of the intubation sheet concentrated droplets onto a smaller area. If no barrier was used, positioning the patient in slight reverse Trendelenburg directed aerosols away from the HCW located at the head of the bed.CONCLUSIONS:Our observations imply that intubation boxes and sheets may reduce HCW exposure to droplets, but they both may merely redirect aerosolized particles, potentially resulting in increased exposure to aerosols in certain circumstances. Aerosols may remain within the barrier device after a cough, and manipulation of the box may release them. Patients should be positioned to facilitate intubation, but slight reverse Trendelenburg may direct infectious aerosols away from the HCW. Novel barrier devices should be used with caution, and further validation studies are necessary.

How the Other Half Looks: The Lower East Side and the Afterlife of Images

How the Other Half Looks: The Lower East Side and the Afterlife of Images

Impact of a small disk on a sessile water drop

We address the details of events that follow the impact of a small solid disk on a water drop sitting on another disk of the same diameter. We experimentally demonstrate that fast squeezing of a low-viscosity liquid drop between two approaching disks leads to the formation of complex, radially expanding liquid structures (splashes) outside of the disks. The spatial and temporal dynamics of these splashes are tracked via high-speed video recording and flash photography. We analyze the mechanisms that control the shapes and breakup processes of these structures and derive a mathematical model for their behavior using simple physical arguments. Our investigation indicates that liquid structure formation is the result of a rapid increase in the velocity of liquid ejection from the gap between disks with time.

Machine Learning Approach to Detect Red-Eye Using Pixel Detection Technique

Sometimes in Flash Photography red colored patches occurred in human eyes. It is actually a reflection of bright flash light reflected from blood vessels in the eyes, giving the eye an unnatural red hue. Red-eye is a big problem in professional photography. Most red-eye reduction systems in many editing software needed the user to identify the red-eye and make an outline through the red-eye. Here we propose an Automatic Red-Eye Detection System instead. The system contains a red-eye detector that finds bunch of red pixels those are clustered to gather, a state of face detector that used to eliminate most false positives (pixel clusters that look red eyes but are not); and a redeye outline detector. All three detectors are automatically learned from the taken datasets and with a proper classifiers using boosting. For creating a fully Automatic Red-Eye Corrector this system needed to be combined with a functional Red-Eye Reduction model.

Laser Research of the Fuel Atomization Process of Internal Combustion Engines

The paper presents test methods (mechanical, electrical and optical) for the fuel spray research in combustion engines. Optical methods, imaging and non-imaging can be used in laboratory and engine tests. Imaging methods include flash photography and holography. Their use is limited to testing droplet dimensions larger than 5 µm. Imaging methods have an advantage over non-imaging ones because they allow the droplet to be seen at the point and time where its measurement is required. Non-imaging methods can be divided into two groups: the first, which counts and measures, individual droplets one at a time, and the second, which measures a large number of droplets simultaneously. Exemplary results of research of droplet size distribution in fuel sprays are shown. In tests of atomized fuel spray, in conditions reflecting the conditions of the internal combustion engine, the size of droplets, their distribution in the spray and the velocity of individual droplets are presented. To determine the quality of the fuel spray, two substitute diameters Sauter (D32) and Herdan (D43) were selected, the first of which refers to heat transfer and the second to combustion processes. Laser research equipment including Particle Image Velocimetry laser equipment (PIV), Laser Doppler Velocimeter (LDV) and Phase Doppler Particle Analyzer (PDPA) were applied for testing fuel spray distribution for two kind of fuel. The atomization process from the point of view of combustion and ignition processes, as well as emission levels, is characterized by the best substitute diameter D43, which value is close to the median volume. The most harmful droplets of fuel in the spray are large droplets. Even a few such droplets significantly change the combustion process and emission of toxic exhaust components, mainly NOx.

Jacob Riis’s Camera: Bringing Light to Tenement Children by Alexis O’Neill

Reviewed by: Jacob Riis’s Camera: Bringing Light to Tenement Children by Alexis O’Neill Elizabeth Bush O’Neill, Alexis Jacob Riis’s Camera: Bringing Light to Tenement Children; illus. by Gary Kelley. Calkins Creek, 2020 [42p] illus. with photographs Trade ed. ISBN 978-1-62979-866-0 $18.99 Reviewed from galleys Ad 6-9 yrs Progressive Era activist Jacob Riis, best known for his photo-illustrated muckraking How the Other Half Lives and his collaboration with then New York Police Board president Theodore Roosevelt, is the focus of this picture book biography, which hustles through Riis’ early years in Denmark to focus on his journalist career and breakthrough idea to rivet public attention on the plight of the poorest tenement dwellers. No stranger to the hardship of immigrant life, Riis devoted himself to clearing substandard housing and bringing sunlight and parks into overcrowded neighborhoods. When passionate prose failed to win hearts, flash photography that captured residents in their squalid tenements proved convincing: “That’s the solution! Words and photographs together. This was the way to show people the truth.” Though O’Neill’s text casts Riis’ crusade as a success, it’s a fairly shallow overview; it notes but never explicitly examines the photographer’s forced entry into apartments or flash powder fires accidentally set, and the displacement of residents in the cleared communities is only mentioned in closing notes. Kelley’s moody ink and pastel illustrations ably capture the overlapping themes of grim poverty and black and white photography technique. Lengthy end matter comprises historical background, a timeline, sources notes, multi-media bibliographies, and selected reproductions of Riis’ photographs. Copyright © 2020 The Board of Trustees of the University of Illinois

Evaluating the relationship between tooth color and enamel thickness, using twin flash photography, cross-polarization photography, and spectrophotometer.

To understand (a) the effects of labial enamel on tooth color (b) relationship of color data taken by nonpolarized (NP), cross-polarization photography (CP), and spectrophotometry (SP). Fifty extracted human maxillary incisors were coated with resin on their palatal surfaces. Their color was measured with NP, CP, and SP and their dimensions were scanned by an intraoral scanner. The labial enamel was removed using a modified selective enamel demineralization technique. Tooth dimensions and color were recorded again. The differences in the labial enamel thickness (ΔT) and color (∆E*00 and ∆L*, ∆a*, ∆b*) were statistically analyzed with the Pearson correlation coefficient and simple linear regression. In CP and SP methods, ΔT and ∆E*00 were weakly to moderately positively correlated (r = .38 and .27). In NP, CP, and SP methods, ∆T and ∆b* are weakly positively correlated (r = .27, .27 and .29). The color data of three measuring methods were highly positively correlated (r > .8). A linear relationship between ∆E*00 and ∆T were found (CP and SP groups). (a) Thicker labial enamel has a greater impact on tooth color. (b) Reducing labial enamel thickness shifts the tooth color toward yellow. (c) Tooth color measured from the three methods were highly correlated. Knowing the relationship between enamel thickness and tooth color, a clinician can better predict the stump shade before tooth preparation. Due to the highly correlated measuring outcomes, it is reasonable to combine these three methods during shade matching.

Exploration of potential triggers for self-directed behaviours and regurgitation and reingestion in zoo-housed chimpanzees

The unique challenges faced by animals living in zoos can lead to the production of anxiety-related behaviours. In this study we aimed to understand what specific factors may cause chimpanzees to display these behaviours. In non-human primates, displacement behaviours, such as self-scratching and yawning, are considered markers of anxiety and stress, and Regurgitation and Reingestion (R/R) is considered an abnormal behaviour with negative consequences for physical health. We examined the possible triggers of R/R, scratching, and yawning in a group of zoo-housed chimpanzees and followed this up with an analysis of long-term data to examine further aspects of R/R behaviour. In the first study we conducted focal observations on 18 adult chimpanzees at Edinburgh Zoo, UK, in addition to all occurrence sampling of visitors using flash photography, screaming and banging on the glass in the exhibit. 158 h of data were analysed and Generalised Linear Mixed Models revealed that yawning was significantly more likely if there was a long period of time since the last feed and when there were moderate numbers of visitors in the zoo. There were trends that yawning was more likely to occur if children screamed and that scratching was more likely to occur if visitors used flash photography. R/R occurred most often within 40 min of a feed, but was not affected by the inter-feed interval preceding that feed, positive or negative social interactions, or visitor numbers or behaviour. As there was no obvious daily trigger for R/R, an analysis of long-term data (2009 to 2015) was conducted to investigate if social or dietary factors affected rates of R/R over a larger timescale. It was found that R/R rates in the months before a significant diet change were not different from R/R rates in the months after, but it was found that R/R rates decreased over the five-year period. Lastly, we found no evidence that the introduction of individuals engaging in R/R lead to resident chimpanzees habitually adopting the behaviour, despite considerable opportunities to observe it. These findings have implications for welfare interventions aimed to reduce R/R and/or anxiety behaviours in captive populations and for the translocation of individuals that are known to engage in R/R between groups.

Why do nocturnal grasshoppers and katydids “salute” to flash photography?

AbstractNocturnal animals can be sensitive to powerful light from the environment. Anthropogenically induced perturbation to natural light regimes, including ecological light pollution and flash photography, can have wide‐reaching implications on the ecology and behavior. Ecological ramifications of strong lights were traditionally focused on vertebrates although there is now more focus on invertebrates. Nonetheless, there are still unanswered questions on visual ecology and evolution, particularly on individual‐level effects and of tropical species. Specifically, how invertebrate individuals react to strong light is generally undocumented. Based on opportunistic surveys around Southeast Asia, orthopterans, spotted using concentrated torchlight and exposed to sudden strong light intensity during flash macrophotography, were observed to screen themselves by positioning their foreleg over the dorsum of the compound eye. This resembled the orthopteran “saluting” to the camera. These observations provided empirical evidence of how high intensity light can unsettle orthopterans and other insects and further ecological and evolutionary hypotheses and questions can be raised to understand the effect of light pollution.