You could drive down the backlight intensity to try and keep the contrast the same, but then the whole screen would start flickering like crazy due to PWM - and that's assuming that the hardware even supports being driven down to that level! It can also be hard to recover if you accidentally drive the backlight down too much or even turn it off altogether!
I'm not sure what you mean -- both my MacBook and iPad let me reduce the backlight intensity to very little, and there's zero "flickering like crazy" at all.
What devices have this problem? I've personally never encountered it on any LCD screens I've ever owned.
> both my MacBook and iPad let me reduce the backlight intensity to very little
I don't agree - I have a long-standing complaint that Apple doesn't let you reduce the brightness on their devices enough! I would definitely want to lower the brightness on my MacBook Pro more at night if I could.
On my Mac I've even used third-party software that overlays the screen with a semitransparent black square to darken it, but that reduces contrast. On my iPhone I use the accessibility filter to darken the screen.
I assume they've limited the minimum brightness due to PWM flicker.
So... yes, I've experimented with that on the Mac too (I think it was "Shady" or something?), so you certainly can.
But that doesn't reduce contrast beyond what's inherent in reducing brightness -- the blacks when the backlight is at minimum power in a dark room are black. You seriously don't get blacker than that in any practical sense that is relevant to the human eye, certainly not on the high-quality displays MacBooks have.
I don't know what you are trying to say with the word "contrast", but a utility like Shady does exactly what you're asking for -- reduces brightness below the minimum -- with zero negative optical side effects. It seems that whatever you're expecting it to do (dimmer but better contrast) is literally a physical impossibility.
