Flicker Effect Research Articles

Dynamic Backlight Scaling Considering Ambient Luminance for Mobile Videos on LCD Displays

The power consumption of mobile devices is always a concern for users due to the constraints on the size and weight of mobile devices. Up to now, mobile video traffic has accounted for the majority of total traffic, which implies that viewing mobile videos has been the major activity when using mobile devices. Among all the subsystems involving in mobile video playback, the display is the most power consuming subsystem. To reduce the power consumption, dynamic backlight scaling (DBS) technique is developed by adjusting the backlight magnitude when playing the mobile video. However, the convenience of mobile devices makes lots of people watch mobile videos in various luminance environments, which makes the existing DBS methods ineffective since ambient luminance varies greatly. In this paper, we propose a novel DBS strategy to maximally enhance the battery power performance under various ambient luminance conditions through backlight magnitude adjusting, while without negatively impacting users’ quality of experience (QoE). In particular, we conduct a series of subject quality assessment experiments to uncover the quantitative relationship among QoE, ambient luminance, video content luminance, and backlight luminance. We then investigate whether the continuous playback of backlight-scaled videos using the proposed scaling magnitude under various luminance environments would cause flicker effect or not. Motivated by the findings of these studies, we implement a novel DBS strategy for mobile energy saving which is suitable for various ambient luminance conditions. The experimental results demonstrate that the proposed DBS strategy can save more than 40 percent power at most and can save 10 percent power even at a very high ambient luminance condition. We also show that the proposed DBS strategy can be easily adapted to different user preferences and different devices, and can be conveniently integrated into practical applications.

Two-Phase Resonant Converter to Drive High-Power LED Lamps

This paper presents the design and modeling of a two-phase resonant converter that drives a LED lamp with a high-frequency pulsed current free of instabilities and flicker effect, fulfilling the recommendations of the IEEE PAR 1789-2015, so that it enables visible light-based communication at a 10 kB/s bit rate. The dynamic study of the converter takes into consideration the effect of the reflected impedance of the output filter on the AC side. In order to evaluate the dynamic response of the converter, a Spice model is defined. A 120 W prototype intended for street lighting applications has been built to validate the analysis and modeling.

Visual-Quality Guided Global Backlight Dimming for Video Display on Mobile Devices

This proposes a visual-quality guided global backlight dimming (VQG-GBD) algorithm to reduce the power consumption of liquid-crystal display on mobile devices. We build a backlight scaling ratio (BSR) prediction model via visual-quality assessment that not only considers the display contents but also the backlight intensity while measuring video quality. Also, we add visual uncertainty as an indicator to dim the backlight without being noticed by observers. The VQG-GBD includes a training stage and an online stage. For the training stage, first, we collect videos with distinct attributes of brightness and uncertainty. Then, the subjective rating obtains the relationship among the visual quality, BSR, brightness, and visual uncertainty. Finally, we use the trust-region method to build the BSR prediction model. In the online stage, the model is applied to mobile devices for real-time video display and a BSR optimization strategy is proposed to eliminate the flicker effect between frames, followed by three techniques to accelerate the process: 1) motion vector extraction; 2) pixel subsampling to reduce the computation while analyzing frame content; and 3) GPU rendering to speed up the pixel compensation. The experimental results show that VQG-GBD achieves 21% of the power demand reduction on average for displaying videos on mobile devices while preserving good visual quality. The VQG-GBD delivers more power reduction than the state-of-the-art algorithm image integrity-based gray-level error control and multi-histogram-based gray-level error control by 10% and 8%, respectively.

Evaluation method and reduction measures for the flicker effect in road lighting using fixed Low Mounting Height Luminaires

Low Mounting Height Luminaires (LMHL) are used in many cities on viaducts, cross-sea and cross-river bridges due to their unique advantages. However, the flicker effect is an important factor that needs to be considered in road lighting using fixed LMHL. At present, there are not many researchers in the field of international lighting. Previous types of road lighting design were based on the method of the tunnel lighting flicker effect. At the same time, the flicker effect is mainly based on the subjective feelings of people but is not quantified. In this paper, the Flicker Index (FI) is calculated by measuring the parameters of streetlamps to evaluation flicker effect. Secondly, the suggestion to offset the flicker effect in CIE 88-2004 “Guide for the Lighting of Road Tunnels and Underpasses” is to limit the speed of the vehicle and adjust the road light spacing to avoid the flicker sensitive area on human eyes, while ignoring the essential problem of how the flicker effect is generated through the energy level of the stimulating optical signal. Two factors affecting the strength of the flicker effect are proposed: energy ratio and duty cycle. The duty cycle, in time, refers to the proportion of the strong and weak flashing signals during the period; in space, it refers to the proportional relationship between the length of the luminaire and the distance between the lamps, which is related to the running speed of the vehicle. It is consistent with the CIE recommendations for flicker. Thirdly, the essence of the flicker effect is the problem of the energy level of the stimulus signal. This study investigated the reduction in the brightness of the light source, hence reducing the energy of the visual stimulation signal to the human eye in order to judge the degree of fatigue in human vision. The experimental results show that the degree of fatigue in human vision decreases when the brightness of the experimental light source decreases. Therefore, the key to changing the flicker effect of LMHL is to reduce the contrast between the surface brightness of the luminaire and the brightness of the spatial background.

Electric Arc Furnace (EAF) Modelling and Comparative Study of Flicker Mitigation Techniques

In the steel production, electrical arc furnace EAF is mainly used for melting the scrap iron. In steel production is increased by using EAF. The EAF is an extremely non-linear and massive power load, but due to EAF is stochastic functioning of an EAF, in the research of the power quality enhancement is motivated. The EAF operation power quality is introduced, the power quality negative consequences decides are characteristics and non-characteristics harmonics, voltage flicker effect, low power factor that arises in the electrical network in operation of the EAF. The quality disturbance are harmonics and current flicker. In the dynamic analysis of the power quality to voltage flicker is studied. The dynamic and static analysis of the EAF we taken examined to study the survival of the voltage flicker in the power system, The analysis of the harmonic is conveyed out to current harmonic is clarify under different types of EAF operation in the power system, so that controller, filter and PWM are used. The controller is hysteresis current and vector current are used to reduce the harmonic through the filter. The pulse width modulation generates the sinusoidal waveform. The EAF operation is beyond the permitted levels as per IEEE references, so as to mitigate the harmonic problems due to an EAF , a rapid dynamic reactive power compensation devices like series passive filter with vector current and hysteresis current controller is being proposed as a solution, The power system has been simulated using MATLAB and the results were tabulated.

High-contrast flicker luminescence on dynamic covalent structure based nanoaggregates

In nanoscience, molecular switches have played a significant role to deliver different control abilities to practical functions, whereas high-contrast luminescence switchable manipulation at nanoscale is still limited. Since the tuning for emission behavior with high contrast ratio strongly connects to numerous visualized sensing and optoelectronic applications, we here report that autonomous pH control can be enrolled to address a high-contrast molecular emission change at the nanoaggregated level, for gaining a flicker luminescence performance in aqueous media. Employing a BODIPY contained dynamic covalent dye, we find its luminescent signal and nanoaggregate size can be spontaneously adjusted in water. On this basis, high-contrast luminescence switching of the material can be achieved upon the alternate introduction of base and acid into the aggregation state. Such a behavior can be attributed to a pH triggered photo-induced electron transfer regulation process. The dye aggregates can be well endocytosed for bioimaging and its luminescent variation can be autonomously displayed as a flicker effect. These results provide new visions for the design and development of smart materials with a dynamic luminescence behavior.

“Tool of Enlightenment”: The Dreamachine’s Effects for Individual Autonomy

Author(s): Oates, Katie | Abstract: Brion Gysin (1916-1986) was an artist, poet, lyricist, linguist, musician, and performer, but first and foremost he was an experimenter and innovator. Spanning 1935 to 1986, his oeuvre illuminates his extreme interdisciplinarity, a quality that has granted him cult status in New York, Paris, and Tangier subcultures, such as the Beats. Though Gysin’s work has been exhibited worldwide, he is best known for inventing the Dreamachine—an apparatus that uses the flicker effect to produce visual hallucinations in the minds of its observers. He conceived of the machine after what he later discovered was the natural flicker effect from the sun. This occurred in 1958 while he was travelling by bus from Paris to the Mediterranean. As the setting sun shone through the branches and leaves of a tree-lined avenue, the fragmented rays of light, combined with the precise speed of the vehicle, produced flashes of light before him. He described the effect this created as: “An overwhelming flood of intensely bright patterns and supernatural colours exploded behind my eyelids: a multi-dimensional kaleidoscope whirling out through space. I was swept out of time.” The brief phenomenon that ended as abruptly as it began—as soon as the bus passed the line of trees—spawned Gysin’s determination to develop a machine that could reproduce the natural phenomenon “at the flick of a switch.”

Border enhancing flicker effect in form-from-motion test

Border enhancing flicker effect in form-from-motion test

A New Flicker Detection Method for New Generation Lamps Both Robust to Fundamental Frequency Deviation and Based on the Whole Voltage Frequency Spectrum

A simplified Voltage Peak Detection (VPD)-based flickermeter based on spectral decomposition is proposed in this paper to detect flicker caused by high-frequency interharmonic components which effect the illumination of next-generation lamps, such as LEDs and compact fluorescent lamps. The proposed VPD-based flickermeter is specially designed to be robust to fundamental frequency deviations, which is a reality of all power systems. The proposed flickermeter is developed using a sinusoidal voltage model and it is analytically shown that flicker depends on the additive effect of the amplitudes of all the interharmonic components. Flicker results obtained by the proposed VPD-based flickermeter, IEC 61000-4-15 flickermeter, and another spectral analysis based IEC flickermeter are all compared with both synthetic voltage waveforms and field data collected from parts of the electricity transmission system with intermittent loads such as electric arc furnaces. It has been shown that only the proposed VPD-based flickermeter is sensitive to the high-frequency interharmonic components in the voltage spectrum and they are not detected by the other flickermeters. In the literature, there is no flickermeter that considers the flicker effect of the high-frequency interharmonic components and gives accurate results in cases of fundamental frequency deviations at the same time.

P‐156: Flicker Effect Depending on the Density of Charge Impurities in the Cell

The concentration of the impurity is higher due to the small device with high resolution. The increased concentration of impurities causes the flicker. In this paper, we observed the flicker effect when charge impurities were generated in the cell and confirmed the flicker effect depending on frequency.

LED driver design for indoor lighting and low-rate data transmission purpose

The LED driver design for lighting at the indoor environment, as well as data transmitter with a one-way link (for download purpose), is discussed clearly in this paper. The LED driver performances are already tested with three scenarios approach and it can work properly. Those approaches are 1) single carrier signal generated by signal generator with offset null as an input signal, 2) integrated with the digital block, i.e. Digital-to-Analog converter (DAC) board which has DC component as an input signal, and 3) using the audio signal as input. The contribution in this paper i.e. 1) the LED driver was simply designed and it could be used for signal with multilevel amplitude format, e.g. audio signals, video signals, orthogonal frequency division multiplexing (OFDM) signal format, etc.; 2) low-cost platform which is built from inexpensive general DIP OP-AMP, 3) can dial up 50 kHz of bandwidth; 4) no flicker effect, therefore harmless for human eyes; 5) light weight implementation and 6) simple to operate with manual tuning. Our proposed LED driver is divided into three stages where each of them, have the main functions, i.e. a) DC-offset remover circuit to remove signal input with has DC signal characteristic, DC-offset summer circuit with a variable amplifier as signal conditioning, and voltage follower transistor.

Development of the Smart Annealing Unit and Analysis of Low-Frequency Conducted Disturbances by Connection to Low Voltage Public Network

Within the research activities, the realization team did the complete development of the annealing unit with the aid of modern technology and components, such as the programmable logic controller, industrial PC, and microcontrollers, to secure an intelligent way of switching the power semiconductor switches (SSR relays) with regard to minimizing the low frequency conducted disturbances. The annealing unit has the implemented algorithm for two ways of output power control, i.e. phase control and full wave control. The algorithm of the full wave control is designed in a way so as to arrange the balanced power in the load. By using this way of control, the harmonic emission is almost entirely eliminated, but the influence of the flicker effect will surface. The article offers a complex view at the annealing unit from the control method perspective, ensuring the correct annealing cycle and subsequent influence of the annealing unit to supply network. It deals deeply with EMC analysis for both ways of designed annealing unit control. The analysis comes out from the experimental measurements on the functional annealing unit prototype.DOI: http://dx.doi.org/10.5755/j01.eie.23.5.19239

Individual Alpha Peak Frequency Predicts 10 Hz Flicker Effects on Selective Attention.

Rhythmic visual stimulation ("flicker") is primarily used to "tag" processing of low-level visual and high-level cognitive phenomena. However, preliminary evidence suggests that flicker may also entrain endogenous brain oscillations, thereby modulating cognitive processes supported by those brain rhythms. Here we tested the interaction between 10 Hz flicker and endogenous alpha-band (∼10 Hz) oscillations during a selective visuospatial attention task. We recorded EEG from human participants (both genders) while they performed a modified Eriksen flanker task in which distractors and targets flickered within (10 Hz) or outside (7.5 or 15 Hz) the alpha band. By using a combination of EEG source separation, time-frequency, and single-trial linear mixed-effects modeling, we demonstrate that 10 Hz flicker interfered with stimulus processing more on incongruent than congruent trials (high vs low selective attention demands). Crucially, the effect of 10 Hz flicker on task performance was predicted by the distance between 10 Hz and individual alpha peak frequency (estimated during the task). Finally, the flicker effect on task performance was more strongly predicted by EEG flicker responses during stimulus processing than during preparation for the upcoming stimulus, suggesting that 10 Hz flicker interfered more with reactive than proactive selective attention. These findings are consistent with our hypothesis that visual flicker entrained endogenous alpha-band networks, which in turn impaired task performance. Our findings also provide novel evidence for frequency-dependent exogenous modulation of cognition that is determined by the correspondence between the exogenous flicker frequency and the endogenous brain rhythms.SIGNIFICANCE STATEMENT Here we provide novel evidence that the interaction between exogenous rhythmic visual stimulation and endogenous brain rhythms can have frequency-specific behavioral effects. We show that alpha-band (10 Hz) flicker impairs stimulus processing in a selective attention task when the stimulus flicker rate matches individual alpha peak frequency. The effect of sensory flicker on task performance was stronger when selective attention demands were high, and was stronger during stimulus processing and response selection compared with the prestimulus anticipatory period. These findings provide novel evidence that frequency-specific sensory flicker affects online attentional processing, and also demonstrate that the correspondence between exogenous and endogenous rhythms is an overlooked prerequisite when testing for frequency-specific cognitive effects of flicker.

A First Approach to Design Mobility Function and Noise Filter in VLC System Utilizing Low-cost Analog Circuits

<p class="0abstract">Visible Light Communication (VLC) as one of wireless technology must be able to offer a good capability as mobile communication system. The signal will be faded when the distance and angle of LED to photo-detector become higher at a certain distance. Other problem at VLC system is light interference noise which is caused by flicker effect from other light sources such as incandescent, fluorescent, DC-lamp (i.e. flashlight) and the sunlight. Each of lights have specific carried signal characteristics and it can influences the VLC system. In this paper we offer design of mobile VLC system based on analog domain. We use Automatic Gain Controller (AGC) circuit using commercially available IC and it will be placed at analog front-end receiver side. AGC can self-adjust its gain according to the input signal amplitude. We also design analog filter to eliminate all interferences noise spectrum which is existed under 50 KHz. We design both circuits, analog filter and AGC in VLC receiver system with low-cost. The test data are obtained through the simulation and achieved good results in ideal condition.</p>

Influence of dynamic highway tunnel lighting environment on driving safety based on eye movement parameters of the driver

In this study, the non-intrusive eye-tracking system Smart Eye Pro was used to record eye movement parameters while drivers were driving through a highway tunnel with two types of lighting environments. The driving safety of the drivers was studied by analyzing the recorded eye movement parameters. The results indicated that the sharp decrease in luminance would result in the change in the position and duration of the fixation point of the driver. The driver performed continuous visual exploration of the unknown highway tunnel lighting environment; this reflects a strong sense of tension. The decreasing luminance, its lower uniformity, and the flicker effect in the tunnel interior zone, resulted in the increase in the pupil diameter of the driver, and the visual load of the driver increased with the change in the rate of increase in the pupil diameter. The eye movement parameters were more stable in a lighting environment with higher luminance on the tunnel sidewall; the optimization of the spatial luminance distribution of the lighting environment and the use of open sun-screens in the entrance portal are recommended for energy saving and traffic safety in highway tunnels.

A two-step solid-state reaction to synthesize the yellow persistent Gd3Al2Ga3O12:Ce3+ phosphor with an enhanced optical performance for AC-LEDs.

By using a two-step solid-state reaction to synthesize the yellow-persistent Gd3Al2Ga3O12:Ce3+ phosphor, both the luminescence and afterglow properties were greatly enhanced. Its internal quantum efficiency reaches as high as 81.9%, indicating its promising application in reducing the flicker effect in AC-LED-based white light systems.

A Practical Electric Arc Furnace Model for Computer Simulation

A practical model of electric arc furnace can help design filters to delay the use life of power line electro-insulating material. This paper proposed a practical simulation model of electric arc furnace. The model is built based on its real output characteristic. It can out put a distort current composed up of n harmonics and non-integer harmonics which re-appear the arc’s cutting off and short circuit phenomenon in melting stage. The current can be set to extrude unbalanced current, interrupted current and half wave imbalance current of each phase. It can also simulate the voltage distortion and flicker effect to other loads. A flicker measure plat is carried out and the model proved to be feasible and realizable. It can realize electric arc furnace output characteristic and is easier to be connected to the power system.

Flickering task-irrelevant distractors induce dilation of target duration depending upon cortical distance.

Flickering stimuli are perceived to be longer than stable stimuli. This so-called “flicker-induced time dilation” has been investigated in a number of studies, but the factors critical for this effect remain unclear. We explored the spatial distribution of the flicker effect and examined how the flickering task-irrelevant distractors spatially distant from the target induce time dilation. In two experiments, we demonstrated that flickering distractors dilated the perceived duration of the target stimulus even though the target stimulus itself was stable. In addition, when the distractor duration was much longer than the target duration, a flickering distractor located ipsilateral to the target caused greater time dilation than did a contralateral distractor. Thus the amount of dilation depended on the distance between the cortical areas responsible for the stimulus locations. These findings are consistent with the recent study reporting that modulation of neural oscillators encoding the interval duration could explain flicker-induced time dilation.

Dependence of image flickering of negative dielectric anisotropy liquid crystal on the flexoelectric coefficient ratio and the interdigitated electrode structure

We experimentally measured the splay (es) and the bend flexoelectric coefficients (eb) of liquid crystal (LC) mixtures with negative dielectric anisotropy and investigated their effect on the image flicker of the LC mixtures driven with a low frequency electric field. Using the experimentally measured es and eb, we simulated the transmittance (TR) response with the continuum model. First, we confirmed that the TR simulation results were approximated to the experimental data with only small variation. Second, we varied the simulation parameters of es, eb, the separation (S), and the width (W) of the interdigitated electrodes and tried to find the optimum condition showing the least image flicker. Given W = 3.0 μm and eb = 5.7 pC m−1, it was found that the image flicker could be minimized when the es/eb value was about 2.4 and the S/W ratio was about 1.5. Because the es/eb value of the rod-like LC material is generally less than 1, it is desirable to design an interdigitated electrode structure to minimize the image flicker effect.

Video quality enhancement based on visual attention model and multi-level exposure correction

Due to unfavorable environmental conditions such as lack of lighting, poor visual quality in images and videos may make intelligent image/video systems unstable. This means that visual quality enhancement plays an important role in image/video processing, computer vision, and pattern recognition. In this paper, we propose a video quality enhancement scheme based on visual attention model and multi-level exposure correction. To this end, the proposed scheme is composed of four parts: pre-processing, visual attention model generation, multi-level exposure correction, and temporal filtering. To extract more visual cues for visual attention model generation, a pre-processing is used to modify each frame. After preprocessing, facial and non-facial cues are measured to generate visual attention maps of each frame. On the basis of visual attention maps, a multi-level exposure correction algorithm is utilized to adjust the exposure level of each frame and then create several intermediate results. After fusing intermediate results, a synthesized image with good visual quality can be obtained. To avoid flicker effect, a temporal filter is exploited to make the variance of the exposure level small in the temporal domain. To evaluate the performance of the proposed scheme, some images/videos captured by mobile phones and digital cameras are tested. The experimental results show that the proposed scheme can effectively deal with the images/videos with low and high exposure levels. The results also demonstrate that the proposed scheme outperforms some existing methods in terms of visual quality.