engine_er I have been looking into this migraine/ eyestrain problem for over half a decade now. I noticed that Gamma is also a cause of headache, besides PWM/ any other flickering. Motorola G200 has a gamma of 1.94(based on report by notebookcheck.net) and this means brighter areas will become much brighter while darker areas will become much more dimmer. An ideal gamma to me is 2.2. Any value lower would be too bright for me.
Color temperature(CCT) is what caused our eyestrain. a perfect pure white light is 6500Kelvins. Notebookcheck reports G200 with 7100K. That's rather bluish and it emits lots of blue light.
I use iphone 7 Plus with a gamma of 2.2 and CCT of 6667K. No PWM as well. I could use it continuously for 12 hours straight without any eyestrain or headache. I have another iphone 8 Plus lying around but I dont use it. Its 6800k color temperature is rather purplish and it causes me mild eyestrain just after 10 minutes of use.
Poco X4 GT may have a gamma of 2.25 and CCT of 6500k, but has a PWM of 51K. I guess 51K may still cause discomfort for you then. For me, 21,000 hz pwm gave me both headache and eyestrain. A 200 hz gave me eyesore (with dry eyes) and a severe migraine with aura, within minutes. The first high PWM that does not give me discomfort is one with over 110K hz.
In summary based on my findings (for very sensitive individuals)
- below 2.2 value Gamma > headache (because content will look very bright)
- above 6500Kelvins/6600Kelvins Color temperature > eyestrain (because of the bluish light emitted)
- low flickering > headache and eyestrain (everyone's threehold for low is different)