scholarly journals Visual Perception in External Lighting Conditions

2021 ◽  
Vol 60 (2) ◽  
pp. 71-78
Author(s):  
Valentyna Polischuk ◽  
Oksana Koliada
Keyword(s):  
Visual Perception ◽  
Spectral Composition ◽  
Light Output ◽  
Night Vision ◽  
Human Vision ◽  
Color Temperature ◽  
Light Sources ◽  
Spectral Radiation ◽  
Surface Reflection ◽  
Lighting Conditions

LED street lighting is a topical trend in modern outdoor lighting. High light output of LEDs creates all conditions for modernization of electric lighting networks in Ukraine. Human vision is a complex process associated with retinal light perception. Vision is divided into: day vision, night vision, and twilight vision. The function of the eye is highly dependent on the distribution of brightness in the field of vision. The spectral sensitivity of photoreceptors varies for different wavelengths of the visible spectrum and different levels of light intensity. The rationing of the lighting installation is based on detailed studies of the observer’s visual performance depending on different lighting conditions. One of the main luminous parameters that can easily be measured objectively is illumination. Brightness as a function of illumination, the observer’s position and the spectral coefficient of the working surface reflection is more informative, but has some difficulty in measuring. There is a clear need to develop a system that would make it possible to uniquely assess the visual efficiency of a given spectral composition under certain observation conditions. It was decided to introduce the term equivalent brightness as the parameter of such a system. The difficulty of using the function Vek(λ,Lek) to calculate the equivalent brightness is the function’s dependence Vek(λ,Lek) on Lek. The aim of the study is to approximate the function of the relative spectral luminous efficiency in mesopathic regions by a set of standard CIE functions that do not depend on the value of equivalent luminosity. The calculation method Vek(λ,Lek) is proposed using only two normalized functions of the relative spectral radiation efficiency for day V(λ) and night V'(λ) vision. The use of such approximation function makes it possible to determine the equivalent brightness, which adequately reflects the level of visual perception under the conditions of ambient illumination, based on the photometric brightness of the light source. To calculate Vek(λ,Lek) we use the ICE recommended functions of relative spectral light efficiency for the twilight vision, which are based on the spectral composition of the blackbody radiation with a color temperature of 2042 K. The use of the developed methodology provides results that more accurately characterize the efficiency of light sources in outdoor lighting installations compared to the results of calculations obtained when using standard methods.

scholarly journals Effects of Different Light Sources on Neural Activity of the Paraventricular Nucleus in the Hypothalamus

Medicina ◽  
2019 ◽  
Vol 55 (11) ◽  
pp. 732
Author(s):  
Michio Yokoyama ◽  
Hyukki Chang ◽  
Hiroshi Anzai ◽  
Morimasa Kato
Keyword(s):  
Paraventricular Nucleus ◽  
Neural Activity ◽  
Light Emitting Diode ◽  
Light Irradiation ◽  
Color Temperature ◽  
Light Sources ◽  
Led Lighting ◽  
Lighting Conditions ◽  
Different Color ◽  
Fluorescent Lighting

Background and Objectives: Physical function is influenced by light irradiation, and interest in the influence of light irradiation on health is high. Light signals are transmitted from the retina to the suprachiasmatic nucleus (SCN) via the retinal hypothalamic tract as non-image vision. Additionally, the SCN projects a nerve to the paraventricular nucleus (PVN) which acts as a stress center. This study examined the influences of three different light sources on neural activity in the PVN region using two different color temperatures. Materials and Methods: Experiments were conducted using twenty-eight Institute of Cancer Research (ICR) mice (10 week old males). Three light sources were used: (1) organic light-emitting diode (OLED) lighting, (2) LED lighting, and (3) fluorescent lighting. We examined the effects of light irradiation from the three light sources using two different color temperatures (2800 K and 4000 K). Perfusion was done 60 min after light irradiation, and then the brain was removed from the mouse for an immunohistochemistry analysis. c-Fos was immunohistochemically visualized as a marker of neural activity in the PVN region. Results: The number of c-Fos-positive cells was found to be significantly lower under OLED lighting and LED lighting conditions than under fluorescent lighting at a color temperature of 2800 K, and significantly lower under OLED lighting than LED lighting conditions at a color temperature of 4000 K. Conclusions: This study reveals that different light sources and color temperatures alter the neural activity of the PVN region. These results suggest that differences in the light source or color temperature may affect the stress response.

Methods for Assessing Quantity and Quality of Illumination

2019 ◽  
Vol 5 (1) ◽  
pp. 479-502 ◽  
Author(s):  
Aurelien David ◽  
Kevin A.G. Smet ◽  
Lorne Whitehead
Keyword(s):  
Solid State ◽  
Electrical Power ◽  
Power Production ◽  
Human Vision ◽  
Light Sources ◽  
Good Reproducibility ◽  
Light Emitters ◽  
High Quality ◽  
Lighting Conditions

Human vision provides useful information about the shape and color of the objects around us. It works well in many, but not all, lighting conditions. Since the advent of human-made light sources, it has been important to understand how illumination affects vision quality, but this has been surprisingly difficult. The widespread introduction of solid-state light emitters has increased the urgency of this problem. Experts still debate how lighting can best enable high-quality vision—a key issue since about one-fifth of global electrical power production is used to make light. Photometry, the measurement of the visual quantity of light, is well established, yet significant uncertainties remain. Colorimetry, the measurement of color, has achieved good reproducibility, but researchers still struggle to understand how illumination can best enable high-quality color vision. Fortunately, in recent years, considerable progress has been made. Here, we summarize the current understanding and discuss key areas for future study.

scholarly journals П’ЄЗОДАТЧИК ЯК ЕЛЕМЕНТ УПРАВЛІННЯ СВІТЛОМ ДЛЯ СТВОРЕННЯ ДИЗАЙНУ ДИТЯЧОГО ПРИМІЩЕННЯ

2022 ◽  
pp. 31-40
Author(s):  
ANNA DZIKEVYCH ◽  
IRYNA OLEINIKOVA
Keyword(s):  
Negative Impact ◽  
Low Cost ◽  
Full Range ◽  
Spectral Composition ◽  
Electricity Consumption ◽  
Color Temperature ◽  
Light Sources ◽  
Design Elements ◽  
Low Level ◽  
Point Light

Purpose. Substantiation and creation of automatic lighting control in interactive rooms using piezoelectric converters. The introduction of this technology will significantly reduce energy consumption during the operation of such premises. The addition of further technological solutions based on the use of phosphor coatings and ultraviolet lighting will create a full range of innovative methods of child interaction in the social space.Methodology. The combination of piezo sensors with design elements such as "live" tiles as a trigger mechanism will create the necessary connection between the physical activity of the child and the regulation of light. The modern level of development and complete safety of materials such as phosphors in combination with specially designed point light sources will make it possible to create additional lighting and a field for the imagination of the child. Since the main attention when lighting children's rooms should be directed to the safe stay of the child, the use of light sources under a translucent floor will solve safety issues with a low level of energy consumption.Findings. An experimental study of the methods has proven the feasibility of using the proposed elements for any interactive children's room. The low cost of both equipment and the energy efficiency of all the technologies used is a significant advantage of this project over other developments with a large use of digital gadgets. The ability of create light of different spectral composition and color temperature is analyzed by using color filters and special light sources.Originality. The technologies and techniques presented in this work will be used for the first time to create interactive activities for a child. Separately, each technological solution was applied individually. This project combines separate developments to create a single interactive and light space. A low level of electricity consumption is achieved by using specially designed piezoelectric elements. Replacing standard ceiling lighting with lower (floor) lighting allows you to achieve the desired illumination using luminaires of lower power.Practical value. Recently, it has been proven that digitalization has a negative impact on the emotional state of the child and the only solution to replace it is to switch the child's attention to other more physically active actions. The proposed solutions in the work will allow their to be involved in group trainings. At the same time, the power consumption for obtaining such rooms will be much lower than the rest of the existing ones. The simplicity of the equipment and the possibility of variation during the operation of the premises make it available for creation in any institution of education, medicine, sports, etc.

scholarly journals METAMERISM INDEX OF LED LIGHT ON HALFTONE COLOUR IMAGES

2021 ◽  
Vol 30 (2) ◽  
pp. 1-9
Author(s):  
Igor Zjakić ◽  
◽  
Ivana Ljevak ◽  
Albulena Bilalli ◽  
◽  
...  
Keyword(s):  
Visual Perception ◽  
Skin Color ◽  
Large Change ◽  
Limited Range ◽  
Light Sources ◽  
Light Conditions ◽  
Colour Temperature ◽  
Led Light ◽  
Lighting Conditions ◽  
Small Index

Skin face detection in photo imaging, is an important component of systems for detecting similarities in visual perception, tracing faces through illumination and metamerism. This paper presents an evaluation of the skin perception under standardized conditions of varied light sources: cool-white fluorescent “store light”, 6500K fluorescent “daylight”, and incandescent “home light”, Led light 6500 K, 2700K, 4000K CCT. In cases where the discrepancy is large, the resulting index of metamerism can be misleading. A small index of metamerism and a large change of color under illuminant metamerism has a different interpretation than what is perceived. This has been demonstrated through small colour variations in print through CMYK colors. The implication is that particular indices of metameric should only account for a limited range under different light conditions. The method used in this paper is based on visual perception, which aim to work with a wide variety of individuals, under varying lighting conditions under the influence of standard daylight, but in this case we also used the Led light 6500K correlated colour temperature, and variations of skin color tones, comparing the illuminant metamerism of visual perception based on different reflectance power distributions (SPDs).

scholarly journals Daylight Spectrum Index: A New Metric to Assess the Affinity of Light Sources with Daylighting

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2545 ◽  
Author(s):  
Ignacio Acosta ◽  
Jesús León ◽  
Pedro Bustamante
Keyword(s):  
Light Source ◽  
Spectral Power ◽  
Color Space ◽  
Human Vision ◽  
Color Temperature ◽  
Light Sources ◽  
Current Scenario ◽  
Electric Light ◽  
Different Color ◽  
Color Rendering

The current scenario of colorimetry shows a wide variety of different metrics which do not converge in the assessment of the color rendering of light sources. The limitations of the Color Rendering Index have promoted the emergence of new metrics, such as the Color Quality Scale. As in the case of the previous metric, these new concepts are based on the analysis of the deviation of different color samples in a color space, contrasting the results with those obtained with a light source reference, which can vary depending on the color temperature. Within this context, the Daylight Spectrum Index is proposed. This new concept aims to determine the affinity with daylighting of electric light sources, comparing the resulting spectral power distributions of the lamps studied and that observed under natural light. The affinity of an electric light source with daylighting allows for lower energy consumption due to the better performance of human vision. The new metric proposed is evaluated following the results obtained from 80 surveys, demonstrating the usefulness of this new concept in the quantification of color rendering of LED lamps and the affinity of electric light sources with daylighting.

scholarly journals Long-Term Reliability Characteristics of OLED Panel and Luminaires for General Lighting Applications

2020 ◽  
Vol 11 (1) ◽  
pp. 74
Author(s):  
Jeungmo Kang ◽  
Yoonhee Cho ◽  
Woojin Jang
Keyword(s):  
Light Emitting Diode ◽  
Light Output ◽  
Color Temperature ◽  
Light Sources ◽  
Operating Voltage ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Reliability Characteristics ◽  
Color Rendering

Organic light-emitting diode is one of the future-proof solid-state-based lighting sources. OLED shows great aesthetic advantages and good color quality without glare. Moreover OLED is a kind of surface light sources naturally. There are some studies on the long-term reliability characteristics of OLED light source. However, these studies focused on the light output degradation of OLED light sources mainly. In this paper, we have investigated the long-term reliability characteristics of OLED panel and luminaires in terms of lumen maintenance, correlated color temperature, color rendering index, and operating voltage. Total twelve OLED panels with four different kinds and six OLED luminaires with two different kinds were analyzed up to six thousand hours and analyzed for the general lighting applications.

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 Constant Optical Power Operation of an Ultraviolet LED Controlled by a Smartphone

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4707
Author(s):  
Ching-Hua Chen ◽  
Jia-Jun Zhang ◽  
Chang-Han Wang ◽  
Yu-Chia Chang ◽  
Pinghui S. Yeh
Keyword(s):  
Uv Light ◽  
Light Output ◽  
Color Temperature ◽  
Constant Light ◽  
Driving Voltage ◽  
Light Power ◽  
Monolithically Integrated ◽  
Uv Led ◽  
Power Operation ◽  
Arduino Uno

Constant light power operation of an ultraviolet (UV) LED based on portable low-cost instrumentation and a monolithically integrated monitoring photodiode (MPD) has been reported for the first time. UV light irradiation has become one of the essential measures for disinfection and sterilization. Monitoring and maintaining a specified light power level is important to meet the criteria of sterilization. We built a module composed of a monolithically integrated UV LED and MPD, a transimpedance amplifier, an Arduino Uno card, a digital-to-analog converter and a Bluetooth transceiver. An Android App that we wrote remotely controlled the UV LED module via Bluetooth. The Arduino Uno card was programmed to receive demands from the smartphone, sent a driving voltage to the LED and returned the present MPD voltage to the smartphone. A feedback loop was used to adjust the LED voltage for maintaining a constant light output. We successfully demonstrated the functioning of remote control of the App, and the resultant UV LED measured power remained the same as the setting power. This setup can also be applied to visible or white LEDs for controlling/maintaining mixed light’s chromaticity coordinates or color temperature. With such controlling and internet capability, custom profiling and maintenance of precision lighting remotely would be possible.

scholarly journals Light Output, Thermal Properties, and Reliability of Using Glass Phosphors in WLED Packages

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 239
Author(s):  
Chin-Chuan Huang ◽  
Tsung-Han Weng ◽  
Chun-Liang Lin ◽  
Yan-Kuin Su
Keyword(s):  
Thermal Properties ◽  
Yttrium Aluminum Garnet ◽  
Saturated Vapor ◽  
Light Output ◽  
Junction Temperature ◽  
Color Temperature ◽  
Light Emitting ◽  
Chromaticity Coordinate ◽  
White Light Emitting Diodes ◽  
Color Rendering

White-light-emitting diodes (WLED) based on yttrium aluminum garnet (YAG) phosphors sintered with glass (PiG) and with silicone (PiS) are compared in terms of their light properties, temperature properties and reliability.The complete YAG phosphor was doped with an encapsulant traditional WLED (PiS WLED), and the WLED was covered with PiG (PiG WLED). PiG was made by sintering glass powder and YAG phosphor at the ratio of 87:13 (%), and the correlated color temperature (CCT) was 5564 K. The CCT of the PiG WLED with the YAG doping concentration of 8.5 wt.% approximated 5649 K. The initial light output of the PiG WLED was 6.4% lower than that of the PiS WLED. Under 1008 h and 350 mA aging, PiG WLED and PiS WLED’ light output, CCT and color rendering index variation rates were all within 1%. In the saturated vapor-pressure test, no sample exhibited red ink infiltration, light nor peeling between the encapsulant and the lead-frame. Compared with that of the PiS WLED, the junction temperature of the PiG WLED reduced from 88.4 °C to 81.3 °C. Thermal resistance dropped from 37.4 °C/W to 35.6 °C/W. The PiG WLED presented a better CIE (Commission Internationale de l’Eclairage) 1931 chromaticity coordinate (x,y) concentration and thermal properties than the PiS WLED.

scholarly journals Photocatalytic techniques to prevent and combat healthcare associated infections

2019 ◽  
Vol 111 ◽  
pp. 04046
Author(s):  
Răzvan Bucureşteanu ◽  
Roxana Apetrei ◽  
Monica Ioniţă ◽  
Ludmila-Otilia Cinteză ◽  
Lia-Mara Diţu ◽  
...  
Keyword(s):  
Light Output ◽  
Antimicrobial Effect ◽  
Light Sources ◽  
Healthcare Associated Infections ◽  
Excitation Light ◽  
Disinfection Process ◽  
Type Semiconductor ◽  
Healthcare Associated ◽  
Areas Of Interest ◽  
Air Circulation

An ever-increasing rate of morbidity and mortality caused by healthcare associated infections is reported annually. Air circulation mediates contact with microbial contaminated aerosols and represents a major risk of transmitting healthcare associated infections. We propose a revolutionary technique for the protection of interior surfaces based on a photocatalytic composition with doped TiO2 or ZnO type semiconductor metal oxides which exert antimicrobial effect. In principle, there is an activation of the photocatalytic coating with light from the normal lighting apparatus, which may incorporate one or more sources of photocatalytic excitation light. By studying the air circulation in the hospital, it is possible to design light fixtures with specific design of light distribution, in order to perform the disinfection of the air and surfaces and to amplify the antimicrobial effect. The disinfection process does not affect patients or healthcare professionals, it can be done in their presence and has a continuous, controllable effect. Photocatalytic paint in combination with a prototype luminaire with a precise spectrum light sources, light output and a light intensity distribution curve relative to the shape and dimensions of the rooms, shows that the proposed method may represent a successful alternative to classical methods of disinfection in hospitals. This technique can also be used in other areas of interest.

Sign in / Sign up

Export Citation Format

Share Document