Why does the LED light flicker frequently on the camera?
What is the stroboscopic effect?
If you browse through older physics books, you’ll find that people generally have a tendency known as the “persistence of vision,” where we can continuously perceive objects even when they no longer appear before our eyes, allowing us to see “continuous images” rather than a series of discrete static pictures.
The high-frequency flickering of LED light sources is imperceptible to the naked eye, so we see the light as on until we completely turn off the power. Similarly, videos are actually a series of rapidly captured consecutive images, recorded at a frame rate per second. When we play games together, this continuous visual effect tricks our brain into perceiving events on the screen as a smooth, fluid motion.
When the frame rate exceeds the frequency of the LED light source, the phone camera exhibits a noticeable flickering effect, known as the stroboscopic effect.
LED lights may flicker when rapidly switching between on and off states, primarily depending on the nature of the current supplied to them. Typically, the flicker frequency of LED lights is extremely high, making it imperceptible to the human eye or effectively invisible. Therefore, people can rest assured that any visible camera flicker actually indicates normal operation of the lights—the only concern should be human blinking. However, stating that LED lights are constantly flickering during operation is an overly broad generalization.
Can the flicker stop?
Stopping the flicker itself is very useless, however, the stimulating flicker effect is what we are trying to eliminate. Although eliminating the flicker effect is an incredible precision task, it can easily be reduced by adjusting the frame rate and shutter speed.
Except for the United States, alternating current is provided at a frequency of 50 hertz, which means that the current changes 50 times between on and off within 1 second. By adjusting camera parameters such as shutter speed and frame rate to multiples or fractions of 50, the flicker effect can be significantly reduced.
Some LED lights are regulated by drivers, and their flicker frequency is controlled by adjusting their switching period. If the flicker rate exceeds the camera frame rate, the flicker effect can be effectively eliminated.
Can incandescent light bulbs also flicker?
Like LED lights, incandescent bulbs switch on and off in alternating current, which means that in the off state, the filament in the incandescent bulb is not sufficiently cooled, which will not have a significant effect on mobile phone cameras. Therefore, we cannot see incandescent bulb flickering on mobile phone cameras.
