Induced contrast asynchronies may be useful for luminance photometry

2004 ◽  
Vol 21 (3) ◽  
pp. 243-247 ◽  
Author(s):  
ARTHUR G. SHAPIRO ◽  
ANTHONY D'ANTONA ◽  
JARED B. SMITH ◽  
LINDSAY A. BELANO ◽  
JUSTIN P. CHARLES
Keyword(s):  
Phase Modulation ◽  
Luminance Level ◽  
The Other ◽  
Visual Effect ◽  
Physically Identical ◽  
Perceptual Separation ◽  
Modulated Light

Shapiro et al. (2004) introduced a new visual effect (the induced contrast asynchrony) that demonstrates a perceptual separation between the response to a modulated light and the response to contrast of the light relative to background. The effect is composed of two physically identical disks, one surrounded by a dark annulus and the other by a light annulus. The luminance levels of both central disks were modulated in time, producing a stimulus with in-phase luminance modulation and antiphase contrast modulation. Observers primarily perceived the disks to be modulating asynchronously (i.e. they perceived the contrast), but at low temporal frequencies could also track the luminance level. Here we document that the induced contrast asynchrony disappears when the surrounds are achromatic and the center lights are modulated near the equiluminant axis. Observers viewed 1-deg-diameter disks embedded 2-deg-diameter achromatic surrounds. The chromaticity of the disks was modulated in time (1 Hz) along lines in an S versus Luminance cardinal color plane and an L-M versus Luminance cardinal color plane; observers responded as to whether the modulation appeared in phase. For all observers and both color planes, the lights appeared in phase most frequently at angles near the standard observer's equiluminant line and out of phase at angles further away from that line. Observers differed in the range of angles that produce the appearance of in-phase modulation. The results suggest that induced contrast asynchronies may be useful as a technique for equating luminance of disparate lights.

Optical spectrum evolution induced by altering input light wavelength spacing

2016 ◽  
Vol 30 (01) ◽  
pp. 1550259
Author(s):  
Minjie Wang ◽  
Caiwen Ma
Keyword(s):  
Phase Modulation ◽  
Optical Spectrum ◽  
Continuous Wave ◽  
Evolution Process ◽  
Light Wavelength ◽  
Optical Fields ◽  
Wavelength Spacing ◽  
Highly Nonlinear Fiber ◽  
Highly Nonlinear ◽  
Modulated Light

This study explored the optical spectrum evolution process using a pump-modulated light and a continuous-wave probe, launched simultaneously into a 1 km highly nonlinear fiber. A total of 70 optical spectra were obtained by each changing the wavelength spacing (0.4 nm) between the probe and pump lights. Simulation results indicated that wavelength spacing between the two beams caused a cyclical optical spectrum evolution process induced by cross-phase modulation. As input light wavelength spacing increased, the coupling between the two optical fields showed obvious attenuation in each neat, multi-peak cycle.

26.—Recent Light on Optical Interference

1972 ◽  
Vol 70 ◽  
pp. 267-280 ◽  
Author(s):  
R. M. Sillitto
Keyword(s):  
The Other ◽  
Light Sources ◽  
Optical Interference ◽  
Low Light ◽  
Intensity Correlation ◽  
Interference Experiment ◽  
Light Intensities ◽  
Light Beams ◽  
Modulated Light

SynopsisThe interpretation of optical interference experiments at low light intensities and with independent light sources is discussed. A new experiment on interference between modulated light beams is described briefly, and its significance is indicated. There are two appendices, one a fuller discussion of the conditions under which interference and intensity correlation may be produced, the other a comment on one aspect of Jánossy and Nagy's discussion (1956) of the feasibility of the alternating slit interference experiment.

Nouvelle approche dans la mesure de la largeur d'une fente

1976 ◽  
Vol 54 (14) ◽  
pp. 1518-1526
Author(s):  
M. Brochu ◽  
C. Delisle
Keyword(s):  
Luminous Flux ◽  
The Other ◽  
Light Distribution ◽  
High Quality ◽  
Quality Instrument ◽  
Modulated Light

A method to measure the width of a slit which is based on the phenomenon of fringes of equal chromatic order is described. The use of spectral fringes for this application is new and differs totally from the method normally used in industrial metrology laboratories. In the latter case, one uses a high quality instrument to measure with precision the distance a slit has to move in order for the operator to bring a carefully adjusted microscopic reticle from coincidence with one edge of the slit to coincidence with the other. In the proposed method, we measure the alternating component of the luminous flux through the slit when a cosinusoidaly modulated light distribution is moved in front of the slit. A null alternating component indicates equality between the width of the slit and the spacing of the fringes. This approach, although requiring more complex instrumentation, introduces a new dimension in industrial metrology related to the measure of the width of a slit.[Journal translation]

scholarly journals The luminance misattribution in lightness perception

Psihologija ◽  
2010 ◽  
Vol 43 (1) ◽  
pp. 33-45 ◽  
Author(s):  
Alessandro Soranzo ◽  
Alessandra Galmonte ◽  
Tiziano Agostini
Keyword(s):  
Visual System ◽  
Luminance Contrast ◽  
The Other ◽  
Lightness Perception ◽  
Low Level ◽  
Dark Background ◽  
Transparent Surface ◽  
Framework Approach ◽  
Physically Identical ◽  
High Level

The Simultaneous Lightness Contrast is the condition whereby a grey patch on a dark background appears lighter than a physically identical patch on a light background. This is probably the most studied phenomenon in lightness perception. Although this phenomenon has been explained in terms of low-level mechanisms, convincing evidences supporting a high-level interpretation have been presented over the last decades. Two are the main highlevel interpretations. On one side, the layer approach claims that the visual system splits the luminance into separate overlapping layers, corresponding to separate physical contributions; whilst on the other side, the framework approach maintains that the visual system groups the luminance within a set of contiguous frameworks. One of the biggest weaknesses of the layer approach is that it cannot account properly for errors in lightness perception (Gilchrist, 2005 Current Biology, 15(9), 330-332). To extend the multiple layers interpretation to errors in lightness perception, in this study we show that the perceptual lightness difference among equal patches on different backgrounds increases even when the luminance contrast with their backgrounds shrinks. Specifically, it is shown that the perceptual lightness difference among equal patches on different backgrounds intensifies when a small-sized semi-transparent surface is interposed between the patches and the backgrounds. This result indicates that in these conditions the visual system besides decomposing the luminance into separate layers also becomes liable for a luminance misattribution. It is proposed that the photometric and geometric relationships among the luminance edges in the image might account for this misattribution.

scholarly journals Recycling Pictures as Attract Point to Youngster in Campus Program Promotion

2018 ◽  
pp. 78-85
Author(s):  
Kartika Kusuma Wardani ◽  
Hertina Susandari ◽  
Anggra Ayu Rucitra ◽  
Arya Weny Anggraita
Keyword(s):  
Three Dimensional ◽  
The Other ◽  
Educational Institutions ◽  
Visual Effect ◽  
Moving Image ◽  
Other Hand ◽  
Complex Process ◽  
Photo Documentation ◽  
Short Time

Educational institutions need promotion tools to attract their segmentation. Promotion medium is used to increase awareness so that the youngster know about information and are interested to register themselves. A medium that has ability to show campus program in short time both attract them is using video. Video is a combination of moving image, sound, visual effect and has complex process to reach best visualization. On the other hand, sometimes the institution only has collection of documentation in photography format. The problem is how to use photo documentation to become short attractive video that shows whole institution programs. Final execution to recycle collection of pictures is using parallax style. This creation of style changes the photos to be more lifelike, which move with three dimensional cinematic effect.

scholarly journals Effects of light emissions from LCD monitors on public health

2014 ◽  
Author(s):  
Wilson Yu ◽  
BCIT School of Health Sciences, Environmental Health ◽  
Bobby Sidhu ◽  
Abderrachid Zitouni
Keyword(s):  
Computer Use ◽  
Luminance Level ◽  
The Other ◽  
P Value ◽  
Blurred Vision ◽  
Healthy Environment ◽  
Computer Vision Syndrome ◽  
Computer Monitors ◽  
Recommended Level ◽  
Room Lighting

  Background: Evidence suggests that exposure to prolonged use of computer monitors may lead to eye discomforts such as eyestrain, blurred vision, headaches, as well as computer vision syndrome. With the increase of internet and computer use at school and work, it raises a serious concern on whether or not the users are affected negatively. Objectives: The following study focuses on estimating the risk of using computers at the British Columbia Technology of Institute (BCIT) laboratories to determine if there is sufficient room lighting (illuminance) and monitor brightness (luminance) to ensure the safety of students at the school. Methods: Illuminance and luminance were both measured by means of a calibrated Unfors Xi light detector connected to a base unit. Several areas of each environment and monitor were measured and average values were taken to ensure that the data was reliable. The data were compared to applicable standards to determine if room lighting and computer brightness at BCIT were appropriate for safe student use. Results: The average illuminance was measured to be 405.4 Lux when the recommended level is 500 Lux. The results are considered statistically significant (p-value = 2x10-6). On the other hand, the luminance measurements averaged a reading of 94.6 cd/cm2 when the recommended minimum luminance level is 80 cd/cm2 (p-value = 0.99964). Discussion: The collected data show that the illuminance inside the BCIT laboratories where testing was conducted is not sufficient while the luminance of computer screens was found acceptable. Conclusion: The measurement of the illuminance inside BCIT laboratories showed that room lighting was insufficient and alternations of the monitor's brightness were made to compensate for insufficient lighting. It is recommended to increase room lighting in the tested laboratories in order to have all areas of the laboratory sufficiently lit at all times. This is to ensure that all students at BCIT are provided with a safe and healthy environment for computer use.  

scholarly journals See What You Feel: A Crossmodal Tool for Measuring Haptic Size Illusions

i-Perception ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 204166952094442
Author(s):  
Olga Daneyko ◽  
Angelo Maravita ◽  
Daniele Zavagno
Keyword(s):  
Three Dimensional ◽  
The Other ◽  
Visual Scale ◽  
Adaptation Session ◽  
Identical Test ◽  
Physically Identical

The purpose of this research is to present the employment of a simple-to-use crossmodal method for measuring haptic size illusions. The method, that we call See what you feel, was tested by employing Uznadze’s classic haptic aftereffect in which two spheres physically identical (test spheres) appear different in size after that the hands holding them underwent an adaptation session with other two spheres (adapting spheres), one bigger and the other smaller than the two test spheres. To measure the entity of the illusion, a three-dimensional visual scale was created and participants were asked to find on it the spheres that corresponded in size to the spheres they were holding in their hands out of sight. The method, tested on 160 right-handed participants, is robust and easily understood by participants.

STABLE AND QUASISTABLE SPATIO-TEMPORAL SOLITONS IN CUBIC QUINTIC NONLINEAR MEDIA

2004 ◽  
Vol 13 (01) ◽  
pp. 25-36 ◽  
Author(s):  
SOUMENDU JANA ◽  
S. KONAR
Keyword(s):  
Numerical Experiment ◽  
Dynamic Behavior ◽  
Phase Modulation ◽  
The Other ◽  
Nonlinear Media ◽  
Kerr Media ◽  
Self Focusing ◽  
Soliton State ◽  
Variational Formalism ◽  
Spatio Temporal

The propagation and stability of spatio-temporal solitons (STSs) under the combined influence of dispersion, diffraction, self-focusing and self-phase modulation in a medium possessing cubic quictic nonlinearity is investigated. Using variational formalism, it has been shown that a pair of soliton state exists, of which, one is stable, while the other quasistable. It has been established that while the stable one is possible only in cubic quintic nonlinear (CQNL) media, the quasistable one is well known in Kerr media. Existence of these solitons is also verified by means of numerical experiment. Moreover, it is also shown that unlike bistable temporal solitons, no spatio-temporal bistable soliton exists in CQNL media. Dynamic behavior of solitons spatial and temporal widths which are different from that of the stationary soliton state is also investigated. Bound oscillatory and unbound regions are identified.

scholarly journals Intelligent Multi-coloured Lighting System Design with Fuzzy Logic Controller

2020 ◽  
Vol 1 (3) ◽  
pp. 128-140
Author(s):  
Paul W. Mutua ◽  
Mwangi Mbuthia
Keyword(s):  
Fuzzy Logic ◽  
Control System ◽  
Energy Efficient ◽  
Fuzzy Logic Controller ◽  
Electrical Energy ◽  
Luminance Level ◽  
The Other ◽  
Lighting System ◽  
Fuzzy Logic Controllers ◽  
Software Environment

This paper describes the design of an intelligent energy efficient lighting system that uses multi-colouredLEDs and a fuzzy logic controller to produce light of the required luminance level and colour in a typical roomspace. The lighting system incorporates automatic control of a room’s window shade opening, convenientlyharvesting daylight. Appropriate room occupancy sensors were set to dim off the LEDs if there are no people in theroom. A movement sensor was also considered for dimming the LEDs if the persons in the room are asleep. A colourdecoder was included in the control system, to determine the LEDs’ output light colour and dim them off if the colourrequirement is not selected. The colour decoder also closes the window shade if required light colour is not white.Two Fuzzy Logic controllers were used in the system; one to control opening of the room’s window shade viamicrocontroller, and the other to control the LEDs’ output luminance. The study was limited to simulation of thedesign in a MATLAB software environment using Fuzzy Logic Toolbox and Simulink blocks. The simulation testresults confirmed that the LEDs’ output luminance decreases as the amount of daylight entering the room increases.The designed system intelligently saves lighting electrical energy while maintaining the room’s comfortableillumination levels and colour requirements.

'Excimer’ fluorescence II. Lifetime studies of pyrene solutions

1963 ◽  
Vol 275 (1363) ◽  
pp. 575-588 ◽  
Keyword(s):  
Binding Energy ◽  
Light Source ◽  
The Other ◽  
Collision Process ◽  
Excimer Fluorescence ◽  
Diffusion Controlled ◽  
Excimer Formation ◽  
The Difference ◽  
Lifetime Studies ◽  
Modulated Light

Measurements have been made of the concentration dependence of the rise and decay time characteristics of the monomer and excimer fluorescence of deoxygenated solutions of pyrene in cyclohexane at temperatures from 293 to 340 °K. Two independent methods were employed, one using a pulsed light source and a pulse-sampling oscilloscope, and the other a modulated light source and a phase and modulation fluorometer. In conjunction with observations of the monomer and excimer fluorescence quantum efficiencies, the results have been analyzed to determine the six rate parameters which describe the behaviour of the system. Values of 6.8 x 10 -7 and 0.9 x 10 -7 s are obtained for the radiative lifetimes of the monomer and excimer, respectively. Excimer formation is shown to be a diffusion-controlled collision process, in which every collision between excited and unexcited molecules is effective. From the difference in the activation energies for excimer dissociation and formation, the excimer binding energy is found to be 0.34eV.

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