OLED displays are a bit different to LCDs. If you’re designing things that will be shown on OLED displays (iPhone XS, Pixel 3 etc), it’s good to be aware of the differences.
Black level and contrast are way better on OLEDs, because there’s no backlight. But, be careful when using pure black — changing pixels from black to any colour is slower than changing from a colour to a colour. This is often called OLED black smearing.
This usually means some part of the image looks like it lags when scrolling or animating. This GIF will show the effect if viewed on an OLED display. It’s reasonably subtle, but easy to spot once you know what it looks like.
The solution: If you’re noticing issues, use a very dark grey instead of black, or slow down the animation.
@marcedwards please please PLEASE give people the choice to not use that, I will take a little bit of smear to have true black any day, dark grey looks so cheap on OLED by comparison
@stevestreza @marcedwards is it possible to have such a dark grey that it's indistinguishable from black that doesn't trigger the smearing?
@seanreilly I don’t think so. I’d love to know more, but I think it might relate to voltage change delta for the pixel. Bigger change = takes more time. Sorry for the delayed reply!
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Here’s a dramatic recreation to make it obvious (and so you can see what it looks like without needing an OLED).