Flicker (light)

rdf:langString Flicker (light)

rdf:langString In visual perception, flicker is a human-visible change in luminous flux 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. Twinkling, also called scintillation, is a generic term for variations in apparent brightness, colour, or position of a distant luminous object viewed through a medium. Flicker exists for other organisms having different perceptual thresholds. Light meters and image sensors can potentially detect flicker at much higher frequency bands than human vision. Shutter speeds used in motion photography can interact with high frequency flicker to produce visual artifacts in the captured imagery that betray flicker that would not otherwise be noted. The spectral sensitivity of the human eye to flicker depends upon the mode of visual perception. Due to the flicker fusion threshold of foveal vision, steady vision can rarely detect flicker above 90 Hz, whereas flicker can be perceived during visual saccades up to or beyond 1 kHz. Flicker due to mechanical factors such as AC line frequency (typically 50 or 60 Hz) will have a stable frequency structure, whereas the flicker of a damp or failing light bulb will often have a chaotic or erratic frequency structure.