scholarly journals Optimized light source spectral power distribution for RGB camera based spectral reflectance recovery

2021 ◽  
Author(s):  
Lixia Wang ◽  
Aditya Sole ◽  
Jon Hardeberg ◽  
xiaoxia wan
Keyword(s):  
Light Source ◽  
Power Distribution ◽  
Spectral Reflectance ◽  
Spectral Power ◽  
Spectral Power Distribution

scholarly journals Influences of Spectral Power Distribution on Circadian Energy, Visual Comfort and Work Performance

2021 ◽  
Vol 13 (9) ◽  
pp. 4852
Author(s):  
Jack Ngarambe ◽  
Inhan Kim ◽  
Geun Young Yun
Keyword(s):  
Light Source ◽  
Power Distribution ◽  
Work Performance ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Essential Element ◽  
Visual Comfort ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Spectral Power Distribution

Spectral power distribution (SPD) is an essential element that has considerable implications on circadian energy and the perception of lit environments. The present study assessed the potential influences of SPD on energy consumption (i.e., considering circadian energy), visual comfort, work performance and mood. Two lighting conditions based on light-emitting diode (LED) and organic light-emitting diode (OLED) were used as proxies for SPDs of different spectral content: dominant peak wavelength of 455 nm (LED) and 618 nm (OLED). Using measured photometric values, the circadian light (CL), melatonin suppression (MS), and circadian efficacy (CE) of the two lighting sources were estimated via a circadian-phototransduction model and compared. Additionally, twenty-six participants were asked to evaluate the said lit environments subjectively in terms of visual comfort and self-reported work performance. Regarding circadian lighting and the associated energy implications, the LED light source induced higher biological actions with relatively less energy than the OLED light source. For visual comfort, OLED lighting-based conditions were preferred to LED lighting-based conditions, while the opposite was true when considering work performance and mood. The current study adds to the on-going debate regarding human-centric lighting, particularly considering the role of SPD in energy-efficient and circadian lighting practices.

scholarly journals Optimising the illumination spectrum for enhancing tissue visualisation

2017 ◽  
Vol 51 (1) ◽  
pp. 99-110 ◽  
Author(s):  
J Shen ◽  
S Chang ◽  
H Wang ◽  
Z Zheng
Keyword(s):  
Biological Tissue ◽  
Power Distribution ◽  
Spectral Reflectance ◽  
Evaluation Method ◽  
Multispectral Imaging ◽  
Spectral Power ◽  
Light Sources ◽  
White Led ◽  
Spectral Power Distribution ◽  
Visual Entropy

In operations, light reflected from biological tissue can be used for disease detection. In this paper, we used a visual entropy evaluation method to design the optimal illuminant to improve colour discriminability of biological tissue. The optimal spectral power distribution of the illuminant was obtained by maximising the visual entropy value of sample tissue based on the human visual system. In the experiment, multispectral imaging was used to measure the spectral reflectance of the tissue and colour clustering was conducted to extract its colour features. To verify the effectiveness of this method, simulated tissue images under illuminations with optimised spectral power distributions were compared with those under other light sources such as the standard illuminant D65 and white LED light sources. Results show that the sample under optimised illumination has a higher visual entropy value with better perceptual visibility.

scholarly journals Spectral Reflectance Estimation Using Projector with Unknown Spectral Power Distribution

2020 ◽  
Vol 2020 (28) ◽  
pp. 205-209
Author(s):  
Hironori Hidaka ◽  
Yusuke Monno ◽  
Masatoshi Okutomi
Keyword(s):  
Power Distribution ◽  
Spectral Reflectance ◽  
Multispectral Imaging ◽  
Imaging System ◽  
Spectral Power ◽  
Low Cost ◽  
Joint Estimation ◽  
Spectral Power Distribution ◽  
Additional Equipment ◽  
Low Dimensional

A lighting-based multispectral imaging system using an RGB camera and a projector is one of the most practical and low-cost systems to acquire multispectral observations for estimating the scene's spectral reflectance information. However, existing projector-based systems assume that the spectral power distribution (SPD) of each projector primary is known, which requires additional equipment such as a spectrometer to measure the SPD. In this paper, we present a method for jointly estimating the spectral reflectance and the SPD of each projector primary. In addition to adopting a common spectral reflectance basis model, we model the projector's SPD by a low-dimensional model using basis functions obtained by a newly collected projector's SPD database. Then, the spectral reflectances and the projector's SPDs are alternatively estimated based on the basis models. We experimentally show the performance of our joint estimation using a different number of projected illuminations and investigate the potential of the spectral reflectance estimation using a projector with unknown SPD.

Smartphone-based measurement of the melanopic daylight efficacy ratio

2019 ◽  
Vol 2019 (1) ◽  
pp. 344-348
Author(s):  
Marcel Lucassen ◽  
Dragan Sekulovski ◽  
Tobias Borra
Keyword(s):  
Circadian Rhythm ◽  
Light Source ◽  
Power Distribution ◽  
General Public ◽  
Spectral Power ◽  
Spectral Power Distribution ◽  
Camera Parameters ◽  
The Absolute ◽  
The Impact

Recently, the CIE published a new standard in which the so called 'melanopic daylight efficacy ratio' (abbreviated to melanopic DER) is introduced. This number is helpful in estimating the impact that a light source may have on our circadian rhythm. Although the melanopic DER can be directly calculated from the spectral power distribution, in case the latter is unknown a spectrophotometer or similar instrument is required, which is usually unavailable to the general public. Here we demonstrate how the melanopic DER can be accurately estimated from a smartphone image of two selected color samples. In addition, using the smartphone's camera parameters we provide a method to estimate the illuminance. Combined these measurements allow an evaluation of the absolute melanopic stimulation.

Supercontinuum laser-based monochromatic radiant source for detector spectral responsivity characterization in the range 0.9–1.6 μm using absolute cryogenic radiometer

2020 ◽  
pp. 28-33
Author(s):  
A. Yu. Dunaev ◽  
A. S. Baturin ◽  
V. N. Krutikov ◽  
S. P. Morozova
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Feedback System ◽  
Operating Mode ◽  
Spectral Responsivity ◽  
Spectral Power Distribution ◽  
Cryogenic Radiometer ◽  
Supercontinuum Laser ◽  
Radiant Power ◽  
Double Monochromator

An improved monochromatic radiant source with spectral bandwidth of 4 nm based on supercontinuum laser and a double monochromator was included in absolute cryogenic radiometer-based facility to improve the accuracy of spectral responsivity measurement in the range 0.9–1.6 μm. The developed feedback system ensures stabilization of monochromatic radiant power with standard deviation up to 0.025 %. Radiant power that proceeds detector under test or absolute cryogenic radiometer varies from 0.1 to 1.5 mW in dependence of wavelength. The spectral power distribution of its monochromatic source for various operating mode is presented.

scholarly journals The spectral power distribution of light and twilight photometry

2017 ◽  
Vol 0 (1) ◽  
pp. 43-52
Author(s):  
Леонід Андрійович Назаренко ◽  
Тетяна Можаровська ◽  
Дмитро Усиченко
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Spectral Power Distribution
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