Beyond the Hz, the depth of the modulation matters. I am sensitive to poor PWM implementation, but Hue bulbs luckily don't bother me.

On an old iPhone with basic slow-mo recording capabilities, typical Hue bulbs don't "blink" when the video plays back, but the PWM-dimmed iPhone in the same video recording was blinking/flashing like crazy.

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Another example of the PWM details mattering: I can't use any iPhone with OLED (anything from the X to current), but I am able to use a Note9 which has OLED with DC-style PWM.

What do you mean by “the depth of the modulation”? The relative brightness?

PWM at low duty cycles tends to be much more noticeable. But that’s where higher frequencies should solve the problem.

I was referring to the extent of brightness variation in the flicker -- while many focus on a higher frequency (Hz) to reduce eyestrain, the key factor is how the screen behaves during the off cycle

Some PWM implementations ramp the brightness up and down slightly (easier on eyes), while other manufacturers flip the switch on and off harshly (like strobing)

The shorter time the screen is dark between being lit up results in a a shorter pulse duration, and the pulse duration and depth are more important than the Hz