async I'm 100% certain that color profile a tinting makes a significant difference as well
My theory is that messing with the color profile gives macOS less "room" to add in those red/blue/yellow fringes around contrasting objects.
Ubuntu is using no color profile at all on the 2009 MBP. I also set macOS to a null color profile. This makes me even more confident about my theory that it isn't necessarily just the pure color adjustment itself (although it does play a part) — instead, it's the fact that making a heavily modified color profile helps limit how much macOS can "enhance" the screen.
Another finding if you're interested:
The most extreme tweak you can do is limit the screen to only use one color — specifically green according to the information about chromostereopsis as it apparently focuses the closest to the physical depth of the display. On Mac you can do this with the bottom 3 image adjustment sliders in BetterDisplay, on Windows the best method is the NegativeScreen app (you can modify the Red preset in its config file to make it green).
Of course, it's good to check with a macro shot of the display whether that actually did entirely turn off the red and blue pixels.
This strategy was surprisingly effective on some Windows laptops for me, but there's some devices that remain unusable even after an extreme change like this.
2015 15" Retina MBP is still unusable even after AMD dither disable + green pixels only. And I think I know why…
- Took a close up shot of 2015 pixels. Even though only green pixels were lit… the darker greens actually shifted towards blue. The way the pixels were manufactured actually shift in physical hue based on intensity (red/blue had similar issues). On some of my other laptops this isn't the case.
- The very blue backlight glow on the 2015 also reinforced darker colors appearing differently.
- Green pixels were slightly lit up even outside of the boundaries of sharp objects, implying either macOS or the panel is adding an intentional glow to everything.
- When using only blue pixels instead of green, there was very red "trails" both when scrolling and even when I just moved my head around. Despite this, could not detect any red pixels even in a slow-motion recording. Given the 2015 has backlight flicker, I have a feeling that the backlight itself was built to alternate between a bluer and redder tone based on intensity. M1 Air and iPhone 14 Pro have similar issues (in appearance — I know that the iPhone OLED isn't backlit).
Finally, both this + last reply I wrote through NoMachine on the 2009 (connecting to my newer Mac). However, this time I'm using NoMachine on Ubuntu instead of Monterey. I'm still using GPU drivers on Ubuntu, and both OSes have dithering fully disabled.
With NoMachine on macOS, even though I was able to write my previous reply and felt "OK", the whole time the letters felt "slightly" floating above the background and the "Post Reply" and the green slider on the right were "popping out at me" on macOS, and I did feel some strain after. This wasn't coming from NoMachine — the whole native macOS Monterey desktop felt like this.
On NoMachine via Ubuntu — with the same quality settings — the 2009 screen feels totally flat, and it's MUCH easier to look at the left side. I feel like I'm more frequently gazing directly at the words (instead of at the gaps between the words).
I'm now 100% confident that there is an (additional) OS-level issue with the macOS compositor, given that even on this laptop that isn't even officially supported, using macOS Monterey is still able to generate issues (albeit more mild than usual)