caboy You’ll probably need to use a third party camera app to get exactly 240 fps slo-mo since the current Apple app won’t do it when set to 240 fps- you can check the actual fps in the info for the video after recording.
I’m not sure what the pixel inversion would look like when zoomed with a microscope, but if I record an iPhone 240 fps video of an LCD monitor if I get the phone as close as I can while keeping the pixels in focus and keep the phone motionless (not handheld), then if the exposure conditions are right (I think fast shutter speed), I’ll get a video where I see something that might be pixel inversion - I’m not sure. On playback, when I zoom in as much as possible to see the pixels better, I’ll see some kind of gray/black movement within white pixels - basically the screen seems to be shimmering. I’m not completely sure what this is. Sometimes I can see colors shifting a bit too - with white parts looking like a mottled rainbow, but the colors shifting position. I’m not really sure what might be temporal dithering, what might be pixel inversion, and whether the matte screen coating is itself creating the mottled color effect.
Pixel inversion is the flip-flipping of voltage across the pixel each frame that is supposed to not always create the same illumination in each polarity. I’m not an expert on screens, but collected some info on this and other issues here: https://www.flickersense.org/background/led-screens