This changed into one of the takeaways from a long discussion approximately digicam sensors for automotive applications. Cars have cameras in them now, some outward facing and some inward dealing with. They’re used for specific functions (extra on that during a second), however the outward-going through ones have a slew of problems to address that I’d in no way considered. One of them is the nasty flickering of highway signs and symptoms. Turns out, maximum digital signs and symptoms by most important roads use LEDs, and contrary to all appearances, those LEDs aren’t surely on all the time. They’re strobed at about 75–80 Hz, partially to shop strength and control brightness. That flickering is invisible to us; our eyes have enough persistence that we perceive the lighting as solidly on. (Old-college fluorescent lights work a whole lot the identical way.) This isn’t a trouble for us humans, but it's miles if you’re a digital camera. Your average CMOS photograph sensor doesn’t have any visible staying power, so it's going to “see” the LEDs turn on and stale numerous times in line with 2d. Depending on the frame fee and shutter pace of your camera, it would see the LEDs on all of the time, off all of the time, or a few pseudo-random aggregate of the two. This is similar to the “helicopter impact,” in which the rotational velocity of the aircraft rotor occurs to match the shutter speed of the film or video digital camera, making it appear like the rotor is stationary even though the craft is flying. Your splendid-grandparents may have recognized this as a zoetrope.