Alp Durmus

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Verified

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• PhD
• Professor (Assistant) at Pennsylvania State University

Displays are the ubiquitous medium to convey information in the modern world. The perceived quality of images seen on displays can be affected by lighting, contrast, and spatial characteristics of the content. While past studies investigated the impact of display luminance and ambient illuminance on preference and discomfort, granular perceptual qu...

Correlated color temperature (CCT) is a one-dimensional metric that aims to quantify the perceived visual quality of nominal white light sources. It is often used as a proxy for the color quality of light sources due to its ease of use. However, CCT lacks the accuracy in communicating color information for research purposes. Two light sources with...

A color space is a three‐dimensional representation of all the possible color percepts. The CIE 1976 L*a*b* is one of the most widely used object color spaces. In CIELAB, lightness L* is limited between 0 and 100, while a* and b* coordinates have no fixed boundaries. The outer boundaries of CIELAB have been previously calculated using theoretical o...

Light is needed to appreciate artwork, but visible radiation causes damage by photochemical action. Photons trigger photochemical action only when they are absorbed by the object. Damage to sensitive materials can be reduced by optimizing the spectrum of a light source to the reflectance factor of a museum artifact. Absorption minimization approach...

Sleep difficulties are highly prevalent among people with autism spectrum disorder (ASD), substantially affecting their well-being and daily functioning. Although the role of indoor light exposure, particularly during evening hours, is well-established in melatonin regulation, circadian functioning, and other physiological responses in general popu...

Color contrast creates visual interest, increases attention, and enhances legibility in the indoor environment. Past studies have suggested that color contrast enhances visual clarity due to the color opponency mechanism of the visual system, especially when two opposing colored samples are seen side by side, such as red–green or yellow–blue. Howev...

Brightness, the perceived amount of light within a luminous environment, significantly impacts the functional and aesthetic quality of the built environment. Previous studies have often used conditions that do not fully replicate real-world settings, highlighting the need for further research in this area to inform better lighting practices. This s...

Lighting in the built environment has evolved since the rapid uptake of solid-state lighting (SSL) devices [...]

Exposure to light can cause fading, discoloration, and other forms of damage to light-sensitive artwork. Pigments and materials used in an artwork have specific spectral absorption and reflectance properties, determining the wavelength of energy they absorb or reflect. By carefully tailoring the spectral power distribution of the light source, it i...

Electric lighting plays a critical role in buildings, not only impacting the well-being, satisfaction, and performance of building occupants but also accounting for a significant portion of energy consumption. The commonly used efficiency metrics for lighting, such as luminous efficacy or lighting power density, fall short of quantifying the effect...

Lighting and color are key factors under the control of lighting designers that can significantly impact shoppers’ perceptions and actions in the context of culinary and retail environments. Previous studies have examined the effects of color and lighting on preference and purchase intent, but results are often conflicting due to confounding variab...

Lighting can impact cognitive functions, emotional states, and visual perception [1-3]. However, its influence on risk-taking behaviors has not been previously investigated. Given the ubiquity of electric lighting in indoor and outdoor settings, understanding its potential effects on decision-making is crucial. This study aims to explore whether ch...

While both music and lighting have been separately studied for their psychological effects [1-3], limited research has explored their combined influence on human perception and cognition. This study aims to bridge the gap by investigating how music paired with chromatic lighting might interact to shape perceptual and cognitive responses. The primar...

In this research, three-channel LED-augmented reality projector spectra were optimised for 24 colour samples using a brute-force (BF) and multi-objective genetic algorithm (MOGA). The BF search and MOGA performed similarly in achieving optimal results, reducing both light absorption and energy consumption by almost half. However, MOGA was 2.5 times...

The widespread use of electric lighting has revolutionised society but brought unintended consequences, notably light pollution, impacting ecosystems and human circadian rhythms. Concerns about anthropogenic light at night (ALAN) have prompted innovative solutions, such as spectral tuning of light sources. In Europe, a recent focus involves the enf...

Solid-state lighting (SSL) devices are ubiquitous in several markets, including architectural, automotive, healthcare, heritage conservation, and entertainment lighting. Fine control of the LED light output is crucial for applications where spectral precision is required, but dimming LEDs can cause a nonlinear response in its output, shifting the c...

In the pursuit of mitigating light pollution and its environmental impact, the use of specific outdoor lighting chromaticities, such as amber and red, has gained attention. However, the implications of these lighting choices on visual quality under low lighting conditions remain relatively unexplored. In this study, a controlled visual experiment w...

PENN STATE researchers investigate the impact of pulse-width modulation dimming methods to determine optimal lighting conditions with LED systems during videography. Architectural lighting design and video production share many similarities in their approach to creating impactful visual experiences. Both disciplines involve the careful consideratio...

The effectiveness of architectural lighting systems has traditionally been measured based on individual luminaire efficiency and cannot capture the performance of intelligent lighting systems. To address this, a lighting application efficacy (LAE) framework has been proposed, which consolidates radiant efficiency, visual system sensitivity, and spa...

Chromatic lighting is often used in specialised applications such as entertainment, theatre, and signage, but there is lack of consensus on metrics that can estimate the brightness of chromatic stimuli. Researchers have previously adjusted colour appearance models (CAMs) to predict brightness of stimuli seem in narrow fields of view. However, metri...

The amount of light in architectural lighting design and research is often quantified using photometric measures, such as illuminance and luminance. Photometric measures are calculated using the photopic luminous efficiency function based on 2-degree visual field of view. However, the original luminous efficiency function V(λ) underestimated sensit...

Light is the primary stimulus for the entrainment of the circadian system. Understanding lighting conditions in realistic spaces has immense health implications. When properly designed, field studies can provide insight into occupants’ daily light exposure and estimate physiological and psychological outcomes. However, measuring the daily light exp...

https://www.ies.org/lda-magazine/featured-content/color/

Researchers have been exploring the influence of light on health in office settings for over two decades; however, a greater understanding of physiological responses and technology advancements are shifting the way researchers study the influence of light in realistic environments. New technologies paired with Ecological Momentary Assessments (EMAs...

Spatial efficiency can be calculated by dividing the radiant flux falling on a work plane by the optical radiant flux emitted from all the luminaires in a given room. However, an alternative method is calculating the ratio of the work plane’s illuminance to the total luminous flux emitted by the lighting system (zonal cavity method). To evaluate th...

Photometric and colorimetric quantities are calculated using spectral luminous efficiency and color matching functions (CMFs), respectively. Past studies highlighted the limitations of the standard sensitivity functions based on visual experiments conducted over a century ago. There have been new alternatives proposed, but the effect of the propose...

Adaptive lighting systems can be designed to detect the spatial characteristics of the visual environment and adjust the light output to increase visual comfort and performance. Such systems would require computational metrics to estimate occupants’ visual perception of indoor environments. This paper describes an experimental study to investigate...

Light is one of the primary stimuli for the entrainment of human circadian rhythms. Past laboratory studies conducted in controlled environments highlighted the importance of photic history, intensity, spectrum, and timing of the light exposure. More recently, field studies indicated that analyzing the real-world impact of lighting on human health...

Light is imperative to achieve viable conditions for human activity at night. However, for the lighting to be sustainable, it is crucial to reduce unwanted and harmful side-effects of light at night (LAN). These unwanted effects and impacts are often referred to as light pollution. Hitherto, it has been somewhat unclear how all these adverse effect...

Multi-primary tunable LED lighting systems can generate a vast number of spectral outputs, with the exact number depending on the resolution of the control signal and number of LED primaries. Computing all combinations to identify optimal spectral power distributions (SPDs) with a specified chromaticity would require a tremendous amount of time and...

Lighting consumes significant energy in buildings, but current measurements of lighting efficiency are inadequate in capturing the spatial and temporal effectiveness of light. The most widely used lighting energy efficiency measure, luminous efficacy, quantifies the amount of light generated by individual light sources. While luminous efficacy prov...

Light at night (LAN) enables humans to extend their lifestyle and exploration, cultivates economic growth, and increases the perception of safety. On the other hand, LAN has been connected to adverse health outcomes, such as circadian disruption, mood effects, and increased breast cancer incidence risk in humans. Studies investigating health outcom...

Spectral reflectance functions has visual and non-imaging forming impacts on occupants. Analyses of a reflectance database indicate a significant difference between natural and artificial surfaces, while color samples were not significantly different than human-made objects.

Occupants’ subjective evaluations of the visual environment can be estimated using image quality assessment metrics. Images captured by a webcam, iPhone, and HDR camera resulted in only small differences in image quality metrics.

Alterative sensitivity functions can be used to improve luminous efficacy and colorimetric calculation accuracy. Analyses found that LEDs are more susceptible to changes in spectral sensitivity functions compared to traditional light sources, especially for CCT.

Visual comfort, task performance, and observers’ satisfaction is affected by the dynamic nature of visual perception and cognition. The perceived quality of the visual environment can be investigated in terms of visual complexity, visual clarity, and visual preference. This paper investigates the relationship between visual preference, visual clari...

Smart lighting systems are based on sensors and tunable lighting systems are increasingly more prevalent, but collecting, analysing, and using the large data generated by these sensors are challenging. Inspired by research on evolutionary algorithms, it can be hypothesized that an adaptive lighting system can operate in real-time by adjusting its o...

Light absorbed by sensitive artwork may cause irreversible damage. Optimising the spectral power distribution of light sources to minimise absorbed light can reduce damage while maintaining the colour appearance of artwork. Previous absorption minimisation studies used optimisation methods without comparing their performance. Here, three channel RG...

The quality of building electric lighting systems can be assessed using color rendition metrics. However, color rendition metrics are limited in quantifying tunable solid-state light sources, since tunable lighting systems can generate a vast number of different white light spectra, providing flexibility in terms of color quality and energy efficie...

Accurately describing the effect of lighting on color appearance phenomena is critical for color science education. While it is ideal to conduct in-person tutorials to demonstrate the color appearance fundamentals, laboratory tutorials have been limited due to COVID-19. The limitation of in-person gatherings and the increase popularity of remote te...

This article explores the best practices for conducting psychophysical experiments that investigate how colour rendition influences the perception of architectural environments. We offer guidance that covers all stages of research from preliminary development to publication, focusing especially on experiments that investigate qualities such as perc...

Phototactic and polarotactic aquatic insects, such as mayflies, can be drawn to electric lighting on bridges at night. Past research investigating the effect of light intensity, polarization, and spectrum on mayflies suggests that a combination of different techniques can reduce the number of mayflies attracted to bridges. Here, various lighting st...

When both the luminous efficacy of lighting devices and the usefulness of the light generated by them is considered, innovative new strategies for illuminating architectural spaces arise that can drastically reduce the energy consumed by lighting without negatively impacting the visual environment.

The spectral power distribution of light sources can be optimized to achieve optimal target goals, such as energy efficiency, color quality, and circadian synchronization. Although several researchers investigated the optimization of light sources for circadian and color rendition metrics, the complex relationship and trade-offs between three disti...

Circadian metrics quantify the non-image forming effects of light. Circadian metrics are based on the spectral power distribution (SPD) and intensity of a light source and human visual and non-image forming response to optical radiation. However, circadian metrics can only estimate static SPDs. Multi-primary LED systems generate a vast number of SP...

Lighting plays a key role in energy consumption in buildings. Despite the increase in the efficacy of solid-state lighting (SSL) devices, such as LEDs, there is a growing energy demand for lighting. In addition, the luminous efficacy of SSL devices is reaching a practical limit [1]. Fortunately, LEDs have the potential to reduce the energy consumpt...

Color and lighting quality assessment allow users to reliably examine the quality of light sources and the changes in the lighting conditions. Technological advance has led to an increase in the development of intelligent systems that are permanently connected to the Internet and that allow access to real time-data. Smart lighting systems have beco...

Light causes damage when it is absorbed by sensitive artwork, such as oil paintings. However, light is needed to initiate vision and display artwork. The dilemma between visibility and damage, coupled with the inverse relationship between color quality and energy efficiency, poses a challenge for curators, conservators, and lighting designers in id...

Previous spectral error estimation studies are focused only on daylight. Spectral sensitivity of three sensors are optimized for electric light sources using a genetic algorithm, which resulted in reduced errors between actual and estimated spectra.

Remote tutorials were designed and performed to demonstrate color appearance phenomena to students. Results suggest that remote lab demonstrations can provide an alternative to in-person lab sessions with caveats and offer additional benefits.

Detecting skin color changes has medical diagnostic value. Spectral optimization of a 16-channel LED for cyanosis observation index, circadian, color, and efficacy metrics underline the benefits of using tunable lighting systems in healthcare facilities.

Researcher ALP DURMUS describes an SSL system that relies on optimized spectral output to achieve integrative lighting’s objective of uniting color science and visual perception studies with intelligent lighting systems for an improved experience.

This article reports on the development of new measures for characterizing color rendition variability (CRV) for multi-primary LED systems that can be controlled to deliver multiple SPDs that have the same chromaticity. The measures, which can be derived from a large set of metameric SPDs for a given product (real or theoretical), illustrate the ra...

An adaptive lighting system can operate in real-time by adjusting its output through a decision-making algorithm based on data mining techniques.

An adaptive lighting system can operate in real-time by adjusting its output through a decision-making algorithm based on data mining techniques.

Optical radiation, including light, plays a crucial role in the structural development of plants through photomorphogenesis and the response to environmental changes. However, plant sensitivity to optical radiation widely varies across species. While research efforts are currently underway to discover the fundamentals of plant physiology, light sou...

There is a wide range of visual and spatial complexity measurement methods that aim to quantify perceived image complexity. While image-based calculation methods (edge detection, image compression, contrast) characterize a digital image, visual perception studies focus on fundamental visual mechanisms, such as contrast sensitivity and visual task p...

The need to achieve energy efficiency standards in the lighting systems of buildings makes it necessary to optimize all aspects of them. Here, the development of a light projection system that achieves this goal by studying and modifying the spectral output, compared to conventional illumination, is described. A lighting system that estimates the r...

ANSI/IES TM-30-18 is an American National Standards Institute (ANSI) approved calculation framework to evaluate the colour rendition of electric light sources. TM-30 specifies several measures, such as the fidelity index (Rf), gamut index (Rg), and local chroma shift (Rcs,hj), as well as the colour vector graphic (CVG) [1]. The CVG is a visual tool...

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Although surfaces impact melanopic response, they are not considered in optimization studies. Calculations with iteratively-generated narrowband LED combinations show that reflectance in short wavelengths has a large impact on melanopic illuminance.

Light is one of the most important elements for residential and work spaces, which affects visual performance, comfort, productivity and well-being. The measures that quantify the characteristics of a light source are derived directly from the spectral power distribution (SPD). In addition, the SPD is an important factor influencing the quality of...

Calculated hue shifts could vary widely for spectrally similar light sources, which suggests a limitation of the current hue shift formulae for non-white light sources. Calculated differences in the hue appearance of 24 colour samples under 279,936 iteratively-generated test SPDs versus two reference illuminants were compared using four hue shift f...

Data science methods can be used to capture, store, and analyze information in real time to extract value, and perform adaptive and predictive user behavior analytics. For example, genetic algorithms are widely used in architectural sciences, including lighting research, to reach optimal conditions. These algorithms offer new possibilities of illum...

Previous studies proposed a smart lighting system that can detect object colors and emit spectrally optimized lighting to reduce the light absorbed by surfaces. The spatial resolution of an absorption-minimization light projection system is investigated using images of various visual complexity. Participants with normal color vision and good visual...

Light source spectrum can be optimized for object reflectance to reduce energy consumption by reducing the amount of light absorbed by surfaces. While the feasibility of this approach to architectural lighting has been demonstrated, this concept has only been tested with objects of highly saturated colors. Here, the color appearance of 24 Macbeth C...

Visual experiments were conducted to quantify blur acceptability in projection systems illuminating complex images. Results show a statistically significant (99 % confidence) increase in blur perception when the circle of confusion increases 3 %.

Alp’s doctoral research investigates ways to reduce the energy consumed by lighting by optimising the spectral power distribution of illumination for object reflectance. Using computational simulations and human experiments, this research will enable the design of advanced lighting systems that detect object colours and project dynamic and customiz...

A mixture of seven narrowband LEDs was optimised to minimise the energy absorbed by coloured objects.

Light is used to illuminate objects in the built environment. Humans can only observe light reflected from an object. Light absorbed by an object turns into heat and does not contribute to visibility. Since the spectral output of the new lighting technologies can be tuned, it is possible to imagine a lighting system that detects the colours of obje...

Previous analyses have shown that optimizing illuminants’ spectral power distributions for object reflectance can yield energy savings in excess of 40% by reducing the light lost to absorption. Here, commercially available LEDs and real objects, instead of theoretical spectra and test sample colors, are investigated. Simulations show that energy sa...

Previous research indicated that energy savings of up to 44% are possible when illuminants’ spectral power distributions are optimized for object reflectance (Durmus and Davis, Opt. Express, 23, A456, 2015). Here, this approach is investigated with commercially available LEDs and real objects, instead of theoretical spectra and test sample colors....

Fuelled by rising consumption power, Southeast Asia has risen to become one of the most reliable and impressive market for LED lightings with an annual growth of 63% since 2013. According to a recent evaluation computed by LEDinside, the total market value for the lighting industry was forecasted to be USD 4.8 billion and USD 1.5 billion will be ge...

Lighting is installed in buildings to enable people to see illuminated objects. The process is simple: light is emitted from a light source, reflects off an object or surface, and then enters the eyes of observers. However, objects do not reflect all light. A large portion of the incident light is absorbed by an object, converted to heat, and does...

Museum lighting is provided to allow visitors to visually perceive displayed works of art, but it also harms illuminated items. Many types of museum exhibits are susceptible to damage caused by exposure to light, and current recommendations for artwork displays include the avoidance of non-visible radiant power, limitations on illuminance levels an...

Computational simulations investigated the minimization of light absorption by illuminating objects with customized two-peak spectral power distributions. Energy savings of up to 71% are possible, without inducing perceptible shifts in object color.