scholarly journals Internet based light quality measurement

2017 ◽  
Vol 4 (1.) ◽  
Author(s):  
Krisztián Samu ◽  
Bálint Thamó
Keyword(s):  
Everyday Life ◽  
Light Source ◽  
Light Quality ◽  
Quality Measurement ◽  
Basic Theory ◽  
Human Interaction ◽  
The Other ◽  
Color Temperature ◽  
Light Sources ◽  
Calculation Methods

The goal of this project was to implement a device, which can measure the illuminance and the correlated color temperature (CCT) of a light source and also works as a webserver. The analyzation of light sources is very important in our everyday life. With the use of a webserver the measured values are easily accessible and the calculation methods can be changed without any changes on the hardware. It also provides a solution to store and analyze the results without further human interaction. Therefore the device is capable of collecting and analyzing a large amount of data. For these criterions we chose a PIC microcontroller, an Ethernet chip and two different sensors. One of the sensors is an RGB sensor and the other one is a LUX sensor. Both of the sensors are using photodiodes to sense the different attributions of a light source. Through this article we show the basic theory behind the project, the implementation and calibration of the device; then the results of the measurements and finally we mention some possibilities for future improvements.

scholarly journals Impact of different standard lighting sources on red jadeite and color quality grading

2019 ◽  
Vol 23 (4) ◽  
pp. 371-378
Author(s):  
Xin Pan ◽  
Ying Guo ◽  
Ziyuan Liu ◽  
Zikai Zhang ◽  
Yuxiang Shi
Keyword(s):  
Light Source ◽  
Color Space ◽  
Sample Surface ◽  
Color Temperature ◽  
Integrating Sphere ◽  
Light Sources ◽  
Light Spectrum ◽  
Fisher Discriminant Analysis ◽  
Fisher Discriminant ◽  
Quality Grading

The purpose of this paper is to investigate the standard light source for grading and displaying the color of red jadeite and to classify the color. With Raman spectrometer, ultraviolet-visible spectrophotometer and X-ray fluorescence spectrometer, the results show that, the Fe 3+ is the main chromogenic mineral of red jadeite, which negatively correlates with the tonal angle, while the color of red jadeite has a positive correlation with the hematite content. The color of 120 red jadeite samples was examined by collecting the reflective signaled from the sample surface using an integrating sphere with the portable X-Rite SP62 spectrophotometer based on CIE 1976 L*a*b* uniform color space. The color parameters of jadeite samples under D65, A and CWF standard light sources were analyzed. The light spectrum of D65 light source is continuous, relatively smoothed with high color temperature, which makes the sample color close to that under the natural light and can be used as the best evaluation light source. A light source contributes to improve the red tone of jadeite, which is the best light source for commercial display of red jadeite. CWF light source can be used as the auxiliary lighting for color evaluation. The color of red jadeite is divided into five levels from best to worst using K-Means cluster analysis and Fisher discriminant analysis under D65 light source: Fancy Vivid, Fancy Deep, Fancy Intense, Fancy dark and Fancy.

Influence of the Parameters of Light Source on Observers’ Visual Performance

2015 ◽  
Vol 731 ◽  
pp. 124-128
Author(s):  
Min Huang ◽  
Zhen Zheng ◽  
Huan Jiang ◽  
Hao Xue Liu
Keyword(s):  
Light Source ◽  
Reading Rate ◽  
Mental Capacity ◽  
Visual Performance ◽  
Color Temperature ◽  
Light Sources ◽  
Accuracy Index ◽  
The Given ◽  
Dose Experiment

In order to investigate the influence of the light source with different illuminance and color temperature on the observers’ visual performance, five kinds of light sources were selected, named LED1, LED2, LED3, LED4 and Fluorescent, which have different illuminance or color temperature. 3 series of visual experiments, such as the ‘find out’ experiment, compared experiment, dose experiment were designed.13 observers were organized to carry out the experiment in the given time in turn. The reading rate, accuracy , index of mental capacity (IMC) and visual comfortable level score were analyzed, the results indicated that the light source with the lower color temperature and medium illuminance has the best visual performance and comfortable visual feel.

scholarly journals Assessing skin tone heterogeneity under various light sources

2020 ◽  
Vol 2020 (1) ◽  
pp. 5-9
Author(s):  
Ruili He ◽  
Kaida Xiao ◽  
Michael Pointer ◽  
Stephen Westland
Keyword(s):  
Light Source ◽  
Color Space ◽  
Color Difference ◽  
Skin Tone ◽  
Color Temperature ◽  
Light Sources ◽  
Facial Image ◽  
Image Capturing ◽  
Facial Area

In this paper, skin tone heterogeneity in five facial areas (forehead, right cheekbone, left cheekbone, nose tip and chin) was investigated under six light sources with correlated color temperature (CCT) of 2850 K, 3500 K, 5000 K, 5500 K, 6500 K and 9000 K. Firstly, a facial image capturing protocol was developed and applied to five female participants, and their facial skin tone was analyzed based on the captured images. Through color characterization of the camera, XYZ values in each facial area were converted by a matrix from the extracted RGB data and then transformed to CAM02-UCS color space. MCDM with CAM02-UCS color difference was used to quantify skin tone heterogeneity in each facial area. The results under different light sources indicated that larger heterogeneity exists under the light source with lower CCT, and when the CCT of the light source ranges from 5000 K to 9000 K, there was smaller skin tone heterogeneity in each facial area.

scholarly journals Design of Smart Light Source based on Bi-color LED with Single Duty Cycle for Correlated Color Temperature Adjustment

2021 ◽  
Author(s):  
Lingyuan Qiao ◽  
Huanyue Zhang ◽  
Jingjie Yu ◽  
Fan Cao ◽  
Yingming Gao
Keyword(s):  
Light Source ◽  
Duty Cycle ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Color Temperature ◽  
Light Sources ◽  
One To One ◽  
Color Mixing ◽  
The One ◽  
Daylight Harvesting

Abstract Color-adjustable light sources facilitate both mood lighting and daylight harvesting. A single duty cycle can be used by a bi-color LED to adjust the correlated color temperature by associating it with the duty cycle of the pulse width modulation dimming signal of the cold and warm light sources. The one-to-one mapping relationship between the single duty cycle and the correlated color temperature is based on the color mixing theory of bi-color LEDs. A method to correlate the dimming signals for cold and warm LEDs is presented. The influence of the time characteristics of the two basic signals on dimming and color temperature adjustment is analyzed. The dimming system of bi-color LEDs is designed, and the method used to adjust the correlated color temperature with a single duty cycle is verified. The experiment showed that the correlated color temperature can be accurately adjusted by the proposed method.

Spectral characteristics of road surfaces and eye transmittance: Effects on energy efficiency of road lighting at mesopic levels

2017 ◽  
Vol 50 (6) ◽  
pp. 842-861 ◽  
Author(s):  
OU Preciado ◽  
ER Manzano
Keyword(s):  
Energy Efficiency ◽  
Light Source ◽  
Spectral Characteristics ◽  
The Other ◽  
Visual Performance ◽  
Light Sources ◽  
Surface Reflectance ◽  
Road Lighting ◽  
Road Surfaces ◽  
Final Effect

In 2010, the CIE published a recommended system for mesopic photometry based on visual performance. According to this system, scenes illuminated at mesopic levels with light sources of high S/P ratio, will produce better visual performance than those illuminated with light sources of a lower S/P ratio at equal photopic luminance. However, there could be other factors affected by SPD that, when quantified, could lead to a contradictory final effect. The scope of this paper was to evaluate how road lighting is affected by the spectral road surface reflectance and by the human eye transmittance as people get older. Our results suggest that the benefits of considering the mesopic vision effect for light sources with high S/P ratios are totally counteracted by the other two effects at mesopic luminances between 0.75 cd/m2 and 1.73 cd/m2 for people between 20 and 60 years of age, depending on the light source and the age of observers.

scholarly journals Assessment of Color Discrimination of Different Light Sources

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 527
Author(s):  
Pedro Bustamante ◽  
Ignacio Acosta ◽  
Jesús León ◽  
Miguel Angel Campano
Keyword(s):  
Light Quality ◽  
Color Discrimination ◽  
Building Design ◽  
Color Temperature ◽  
Light Sources ◽  
Accurate Evaluation ◽  
Color Rendering Index ◽  
Color Rendering ◽  
New Procedures ◽  
Key Parameter

Light quality is a key parameter of building design, which is mainly defined by the perceived luminance and the color rendering. Nowadays, there is a wide variety of metrics that do not converge in the color rendition evaluation of current light sources. The obsolescence of the Color Rendering Index promoted the rise of new procedures to provide an accurate evaluation. However, the score provided by most of these metrics does not distinguish between color deviation and hue discrimination, giving a single value to assess the overall color perception allowed by a light source. In this context, a new study is proposed, based on the evaluation of seven different light sources, comparing the results of the most recent color rendering metrics and those observed using a Farnsworth–Munsell trial carried out with 115 participants. The results obtained show that there is a notable divergence between color rendition and hue discrimination, although there is a clear proportionality between both. Moreover, a clear relationship is observed between color discrimination and the correlative color temperature of light sources, providing a better hue distinction with cool light sources, even though the psychological preferences of the participants do not coincide with the optimal scenario for color discrimination.

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.

Research on Visual Performance under Different Lighting Environments of LED Light Sources

2015 ◽  
Vol 731 ◽  
pp. 92-96
Author(s):  
Yu Liu ◽  
Hong Tao Miao ◽  
Min Huang ◽  
Ai Ping Liu ◽  
Xian Yao Wu
Keyword(s):  
Light Source ◽  
Visual Task ◽  
Visual Performance ◽  
Color Temperature ◽  
Light Sources ◽  
Physiological Changes ◽  
Led Light ◽  
Low Illumination ◽  
Different Color ◽  
The Relationship

In order to study the LED light source illumination and the correlated color temperature effect on the human eye visual performance and physiological changes, through the comparative experiments of visual task performances under the different color temperature (3000K low color temperature, 4000K intermediate color temperature) and the different illumination (1145lux high intensity, 500lux middle intensity, 288lux low illumination), study the relationship between the biological effect and visual performance from two aspects of the visual perception performance and the physical efficiency such as blood pressure and pulse. Research indicates that color temperature 3000K or 4000K, intensity of illumination in about 500lux LED light source is suitable to visual task.

scholarly journals What is the optimal light source for optical mapping using voltage- and calcium-sensitive dyes?

2020 ◽  
pp. 599-607
Author(s):  
V Olejnickova ◽  
D Sedmera
Keyword(s):  
Light Source ◽  
Optical System ◽  
High Speed ◽  
Optical Mapping ◽  
The Other ◽  
Mouse Heart ◽  
Xenon Lamp ◽  
Light Sources ◽  
High Speed Imaging ◽  
Advantages And Disadvantages

Optical mapping is a fluorescence-based physiological method to image spreading of action potential in excitable tissues, such as the heart and central nervous system. Because of the requirements for high speed imaging in low light conditions, highly sensitive high-speed cameras together with an optical system with maximum photon efficiency are required. While the optimization of these two components is relatively straightforward, the choice of the perfect light source is less simple; depending on the other (usually fixed) components, various parameters may acquire different weight in decision-making process. Here we describe the rationale for building an optical mapping setup and consider the relative advantages and disadvantages of three different commonly available light sources: mercury vapor lamp (HBO), xenon lamp (XBO), and light emitting diode (LED). Using the same optical system (fluorescence macroscope) and high-speed camera (Ultima L), we have tested each of the sources for its ability to provide bright and even illumination of the field of view and measured its temporal fluctuations in intensity. Then we used each in the actual optical mapping experiment using isolated, perfused adult mouse heart or chick embryonic heart to determine the actual signal to noise ratio at various acquisition rates. While the LED sources have undergone significant improvements in the recent past, the other alternatives may still surpass them in some parameters, so they may not be the automatic number one choice for every application.

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