Screen Uniformity Test

The screen uniformity test fills your display with flat gray and white fields, one shade at a time. A perfectly uniform panel shows each field as a single, even tone from corner to corner. Real panels rarely manage that, so the test helps you judge how far yours drifts and whether the difference matters at your desk.

Mid-gray backgrounds are the most revealing. Uneven backlighting, dirty screen effect, and faint vertical or horizontal bands stand out on 25 and 50 percent gray far more than on white or black. The white field exposes color tint, where one side of the screen looks slightly warmer or cooler than the other. The dark field shows clouding, the soft bright patches that appear when the backlight is not spread evenly.

Give the display 20 to 30 minutes to warm up before you judge anything. A cold backlight can show temporary unevenness that disappears once the panel reaches its normal temperature. Set brightness to the level you actually use, sit in your normal position, and compare the center of the screen with the edges and corners. Keep your head still, because viewing angle changes what you see on most LCD panels.

The test runs entirely in your browser and does not capture, upload, or store anything. It cannot measure brightness in numbers the way a colorimeter can, but it makes the differences your eyes can detect much easier to find.