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Flicker vertigo, sometimes called the Bucha effect, is "an imbalance in brain-cell activity caused by exposure to low-frequency flickering (or flashing) of a relatively bright light." [ 1 ] It is a disorientation -, vertigo -, and nausea -inducing effect of a strobe light flashing at 1 Hz to 20 Hz, approximately the frequency of human brainwaves .
Intentional light variations are applied for warning, signalling (e.g. traffic-light signalling, flashing aviation light signals), entertainment (like stage lighting) with the purpose that flicker is perceived by people. Generally, the light output of lighting equipment may also have residual unintentional light level modulations due to the ...
In visual perception, flicker is a human-visible change in luminance of an illuminated surface or light source which can be due to fluctuations of the light source itself, or due to external causes such as due to rapid fluctuations in the voltage of the power supply (power-line flicker) or incompatibility with an external dimmer.
The flicker fusion threshold, also known as critical flicker frequency or flicker fusion rate, is the frequency at which a flickering light appears steady to the average human observer. It is a concept studied in vision science , more specifically in the psychophysics of visual perception .
The flicker of a CRT monitor can cause various symptoms in those sensitive to it such as eye strain, headaches [9] in migraine sufferers, and seizures in epileptics. [10]As the flicker is most clearly seen at the edge of our vision there is no obvious risk in using a CRT, but prolonged use can cause a sort of retinal shock where the flickering is seen even when looking away from the monitor.
Temporal light artefacts (TLAs) are undesired effects in the visual perception of a human observer induced by temporal light modulations. Two well-known examples of such unwanted effects are flicker and stroboscopic effect. Flicker is a directly visible light modulation at relatively low frequencies (< 80 Hz) and small intensity modulation levels.
Flashing lights (such as strobe lights) or rapidly changing or alternating images (as in clubs, around emergency vehicles, near overhead fans, in action movies or television programs, etc.) are examples of patterns in time that can trigger seizures, and these are the most common triggers. Static spatial patterns such as stripes and squares may ...
In a television studio, a tally light (or on air indicator) is a small signal lamp on a professional video camera or monitor. It is usually located just above the lens or on the electronic viewfinder (EVF) and communicates, for the benefit of those in front of the camera as well as the camera operator , that the camera is live (i.e. its signal ...