A comparison of color fidelity metrics for light sources using simulation of color samples under lighting conditions

2017 ◽  
Author(s):  
Hyeokjun Kwon ◽  
Yoojin Kang ◽  
Junwoo Jang
Keyword(s):  
Light Sources ◽  
Lighting Conditions

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.

Effect Of Chromaticity Of Surrounding Light Sources on Mesopic Adaptation Luminance

2021 ◽  
pp. 30-38
Author(s):  
Sangita Sahana ◽  
Biswanath Roy
Keyword(s):  
Light Source ◽  
The State ◽  
Light Sources ◽  
Ambient Light ◽  
Lighting Conditions

This paper presents variations in mesopic adaptation luminance in the presence of ambient light sources along with main light source for outdoor lighting applications. Mesopic photometry system is based on peripheral task, and adaptation luminance is required to compute the effective mesopic radiance for the measured area. Different lighting conditions were considered to determine the effect of chromaticity of bright surrounding sources other than the main light sources to the state of observer adaptation. The veiling luminance caused by the surrounding sources increases the state of observer adaptation, but not the luminance within the measurement field. It has also been observed that in case of cool white surrounding sources, adaptation luminance increases significantly than that of warm white sources.

scholarly journals Spatial–Spectral Evidence of Glare Influence on Hyperspectral Acquisitions

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4374
Author(s):  
Alberto Signoroni ◽  
Mauro Conte ◽  
Alice Plutino ◽  
Alessandro Rizzi
Keyword(s):  
Hyperspectral Image ◽  
Imaging System ◽  
Reflectance Spectra ◽  
Hyperspectral Images ◽  
Imaging Systems ◽  
Light Sources ◽  
Optical Phenomenon ◽  
Lighting Conditions ◽  
First Time ◽  
Glare Effect

Glare is an unwanted optical phenomenon which affects imaging systems with optics. This paper presents for the first time a set of hyperspectral image (HSI) acquisitions and measurements to verify how glare affects acquired HSI data in standard conditions. We acquired two ColorCheckers (CCs) in three different lighting conditions, with different backgrounds, different exposure times, and different orientations. The reflectance spectra obtained from the imaging system have been compared to pointwise reference measures obtained with contact spectrophotometers. To assess and identify the influence of glare, we present the Glare Effect (GE) index, which compares the contrast of the grayscale patches of the CC in the hyperspectral images with the contrast of the reference spectra of the same patches. We evaluate, in both spatial and spectral domains, the amount of glare affecting every hyperspectral image in each acquisition scenario, clearly evidencing an unwanted light contribution to the reflectance spectra of each point, which increases especially for darker pixels and pixels close to light sources or bright patches.

RESEARCH OF LIGHTING CONDITIONS BY LED LIGHT SOURCES SECOND GENERATION

2019 ◽  
pp. 53-56
Author(s):  
O. E. Zheleznikova ◽  
S. Juma Mohammed ◽  
A. N. Mikhal’kova ◽  
S. A. Mikaeva
Keyword(s):  
Second Generation ◽  
Light Sources ◽  
Led Light ◽  
Lighting Conditions

scholarly journals Active Recurrence of Lighting Condition for Fine-Grained Change Detection

2018 ◽  
Author(s):  
Qian Zhang ◽  
Wei Feng ◽  
Liang Wan ◽  
Fei-Peng Tian ◽  
Ping Tan
Keyword(s):  
Change Detection ◽  
Light Source ◽  
Real World ◽  
Reference Image ◽  
Light Sources ◽  
Lighting Condition ◽  
Fine Grained ◽  
Lighting Conditions ◽  
Point Light ◽  
Change Monitoring

This paper addresses active lighting recurrence (ALR), a new problem that actively relocalizes a light source to physically reproduce the lighting condition for a same scene from single reference image. ALR is of great importance for fine-grained visual monitoring and change detection, because some phenomena or minute changes can only be clearly observed under particular lighting conditions. Hence, effective ALR should be able to online navigate a light source toward the target pose, which is challenging due to the complexity and diversity of real-world lighting \& imaging processes. We propose to use the simple parallel lighting as an analogy model and based on Lambertian law to compose an instant navigation ball for this purpose. We theoretically prove the feasibility of this ALR strategy for realistic near point light sources and its invariance to the ambiguity of normal \& lighting decomposition. Extensive quantitative experiments and challenging real-world tasks on fine-grained change monitoring of cultural heritages verify the effectiveness of our approach. We also validate its generality to non-Lambertian scenes. 

Reconstructing Artificial Light in Ancient Greece

2017 ◽  
Author(s):  
Dorina Moullou ◽  
Fragiskos V. Topalis
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Ancient Greece ◽  
Artificial Light ◽  
Light Sources ◽  
Colour Discrimination ◽  
Colour Perception ◽  
Relative Ease ◽  
Artificial Lighting ◽  
Lighting Conditions

This chapter presents an overview of artificial lighting means and their efficiency in the performance of domestic nocturnal activities (except cult practices) in ancient Greece. Through experiments conducted in the Lighting Laboratory of the National Technical University of Athens, the optical properties of exact copies of ancient light sources are investigated. The experimental data are used to assess the sufficiency of light produced by the lighting devices, and to examine the resulting lighting conditions in relation to colour perception and domestic nocturnal activities. The results show that people in antiquity could move around and operate with relative ease at night. Most domestic nocturnal activities could be performed even by the light of a single lamp, provided that it was located relatively nearby. Activities involving colour discrimination, such as weaving, were the most difficult but not impossible to perform. Therefore, artificial light in antiquity could be both effective and economical.

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.

A new machine-vision-based approach for rapid dimensional inspection of an integrated circuit carrier tape

2009 ◽  
Vol 223 (3) ◽  
pp. 145-154
Author(s):  
S-H Chen ◽  
T-T Liao ◽  
C-T Chen
Keyword(s):  
Machine Vision ◽  
Integrated Circuit ◽  
Ccd Camera ◽  
Light Sources ◽  
Charge Coupled Device ◽  
Lighting Conditions ◽  
Environmental Lighting ◽  
Canny Edge ◽  
Edge Detection Method ◽  
A Charge

This study presents a rapid and reliable machine vision technique for measuring the principal features of interest in an integrated circuit carrier tape, namely the diameters of the circular sprocket perforations and centre hole, the width of the carrier tape, and the width and length of the centre cavity. In performing the measurement process, the quality of the image acquisition process is enhanced by using two auxiliary light sources to suppress the effects of natural variations in the environmental lighting conditions. Having acquired the image using a charge coupled device (CCD) camera, the features of interest are separated from the background region of the image using a two-threshold algorithm based on the Otsu threshold selection method. The edge of each feature is then extracted from the binary image using the Canny edge detection method. The dimensions of the circular features are obtained by fitting four right-angle triangles within the periphery of the extracted circular edge and then computing the circle diameter by taking the mean of the hypotenuse values of the four triangles as computed using the Pythagorean theorem.

scholarly journals Realtime flicker removal for fast video streaming and detection of moving objects

2021 ◽  
Author(s):  
Jarosław Nowisz ◽  
Michał Kopania ◽  
Artur Przelaskowski
Keyword(s):  
High Speed ◽  
Moving Objects ◽  
Sufficient Accuracy ◽  
Light Sources ◽  
Movement Detection ◽  
Review System ◽  
Improve Technique ◽  
Original Solution ◽  
Lighting Conditions ◽  
Computer Vision Systems

AbstractHigh-speed cameras are used in computer vision systems to track balls, shuttlecocks, or players in many different sports. Collected information is used for statistics, as coaches’ and players’ aids to improve technique and tactics or as referees’ aids to verify their decisions or to enrich television broadcasts. Sports arenas in which games are played are often equipped with lights generating flickering effects in captured movies. A fast and yet effective enough algorithm is necessary to remove flickering so movement detection and object tracking algorithms could be used. In this paper, we propose a fast flicker removal algorithm working as an online filter on frame streams at speeds exceeding 200 frames per second. Most of the solutions found in literature concentrate on effectiveness and accuracy and not on the speed of operation. In contrast, our original solution is designed with speed in mind with sufficient accuracy to be used before calculating differential frames to detect movement in streams. Our algorithm is adaptive and works when lighting conditions are changing (new light sources) and performs well with various light sources that are causing flickering. The results of the experiments carried out show the high effectiveness of the method implemented on CPU and GPU, allowing effective tracking of objects of interest in preliminary applications of a commercially offered instant review system for badminton.

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