Sunspark there's clearly so many variables to be tested. What are you sensitivities and which display are you currently comfortable with?
Sentiny it should be plenty safe. I don't like True Tone personally but I don't think of these options will re-enable dithering, but again can only be known with proper testing. You can also re-check iroeg to see enableDither was set to Yes again.
Donux try your phone manual video mode option with the fastest shutter speed. You need to test an image with a white background. Do you trust this method?
async the idea would be to edit the EDID in the capture card, and then capture the output to see how the a particular config affects the image. You can then diff and run the capture through ffmpeg or whatever other tools to see the difference.
twomee Which external display brand and model are you using?
DisplaysShouldNotBeTVs I'm not working on an iOS version since I don't use iPhones and currently do not have the time to pursue this. I'll tinker around but no promises. In any case, my code and methodology are open source so anyone can pick up where I left.
photon78s thanks for the Carson MicroFlip recommendation. Because despite disabling dithering at the GPU level there's the question of whether the external display panel does dithering/FRC on its own. Can't trust manufacturer specs when it comes to these things.
markdotpeters5 do you have an M1 Mac? Download the app and try it. I tested with M2 and M3 and it worked flawlessly. Would love an M1 datapoint.