Video points out that pulse-width modulation LED dimming technique may confuse cameras.

If you’ve ever shot (or seen) footage where of, say, the rear lights of a newer car that has LEDs instead of traditional light bulbs, then you will undoubtedly have noticed the flickering. You don’t perceive the flickering with the naked eye, but cameras usually do and since self driving cars do rely on cameras, it could pose a serious problem for them.

This occurs due to the way LED brightness is varied, through a technique called pulse-width modulation. What this essentially means is the LED turns on and off at a certain frequency; the lower the frequency, the lower the perceived brightness and vice-versa.

Now this doesn’t affect how human eyes perceive the light - we can’t tell it’s not actually constant - but if a camera’s refresh rate is synchronized with the LED’s flicker rate, then it might appear that it’s actually flickering.

This video, courtesy of Steve Mould, points out that this could baffle self-driving cars which will rely on cameras to read traffic conditions and adapt. He suggests, for instance, that if a car in front of an autonomous vehicle slams on its brakes, the autonomous vehicle might mistake this for the hazard lights being turned on; do note that LEDs are also are also used in traffic lights.

This is certainly an interesting point of view, and a valid concern, even if we don’t know of any problems officially reported and related to this being an issue. But automakers will certainly want to make sure it doesn’t become a problem, especially since pretty much all new cars have ditched filament bulbs for diodes and it’s a trend set to continue.

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