OLED near-black uniformity: what's normal and what isn't

How this is calculated

Driving an OLED pixel at a very low level is hard to do evenly. Tiny differences in each pixel's response turn into visible variation, often as vertical bands, a blotchy texture, or slightly tinted patches. Makers use compensation routines to even this out over time, often during standby, so results can change after the screen has been used for a few days. Use the dark gray pattern, which sits at about 10% of full white, and the near-black steps in the Black and white levels check, which go down to code value 1. Look in a dim room at your normal brightness first. Then raise the room light to your usual level and look again. Note whether the bands or blotches stay in the same place. Keep an eye out for things that aren't panel faults: some OLEDs dim the whole screen when a static image stays up for a while, which can look like a change in uniformity. Moving to the next pattern and back resets that. Avoid long sessions with a single static test image on an OLED, since leaving any static image up for a long time isn't good for the panel. The test's patterns don't need more than a minute each.

Verdict

Check near-black on a new OLED after it has had a few days of normal use and its compensation cycles have run, unless the problem is severe on day one. Faint variation that only shows on a dark gray test is common. Banding or blotches that you see in dark scenes at your normal settings are worth reporting to the seller. Check the maker's support pages for your model's compensation and pixel refresh features, since each maker names and schedules them differently.