White Level Test
Check how bright and how neutral your monitor drives pure white. A full-screen white field exposes tint and uniformity, while near-white steps and a grey-to-white gradient reveal highlight clipping and lost detail. Set mainly by the Contrast control.
← → change pattern
The Contrast control scales the brightest tones. Too high clips highlight detail; too low leaves whites dull and grey. Set black level with Brightness first.
On the near-white pattern, tune Contrast until levels 254 and 253 are only just visible against pure white without merging into it.
If white looks yellow or blue, set the colour-temperature preset to 6500K and fine-tune with the RGB gain (white balance) sliders. This is a visual guide, not a measurement.
What does each pattern show?
| Pattern | What it reveals | A healthy panel shows |
|---|---|---|
| Pure white field | Colour tint and uniformity (the dirty-screen effect) | A clean, even level-255 white — no yellow or blue cast, no smudges or corner-to-centre unevenness |
| Near-white steps | White clipping (blown highlights) | Patches at 254, 253, 252, 250, 248, 245, 242, 238 and 232 all just separate from pure white |
| Grey-to-white gradient | Where highlight detail is lost | A smooth climb to level 255 with the steps staying distinct all the way to the end |
White level is how bright and how neutral your display drives pure white — the level-255 signal. It is set mainly by the Contrast control, which scales the top of the tone range, while Brightness sets the black level at the bottom. Set right, white looks clean and bright without crushing the faint tones just below it, and a correct white point (colour temperature) keeps it neutral rather than warm or cool. Peak white and black level are the two anchors of your panel's dynamic range, so white level pairs naturally with a black-level or contrast check.
When Contrast is too high, the brightest levels all clip to maximum output and become indistinguishable — blown highlights. It shows as the top steps (254, 253, 252) merging into pure white, or the gradient flattening to a solid band before the right edge; lower Contrast until those steps reappear. It isn't always the monitor's fault — a wrong signal range (limited vs. full RGB) or an aggressive dynamic-contrast mode can clip whites on its own.
To set white level, turn off any dynamic-contrast or "eco" mode, set the black level with Brightness first, then raise Contrast until whites look bright and back off until levels 254 and 253 are just visible against pure white. Set the colour-temperature preset to 6500K (often "Warm" or "sRGB") for a neutral white, and use the RGB gain (white balance) sliders to clear any remaining tint. Cross-check with the Contrast Test for the full black-to-white range and the Gamma Test for mid-tones.