Monitor Test

An online monitor test fills the screen with solid colours, pure white, pure black and grayscale steps, and each pattern isolates a different fault. Solid red, green and blue reveal dead and stuck pixels, while pure black shows backlight bleed and IPS glow near the edges. White and the gray steps expose uneven brightness, colour tint across the panel and banding. It is a quick, no-software check worth running on any new or used display before the return window closes.

To check for backlight bleed, set the screen to solid black in a dark room and look at the edges and corners. Lighter glowing patches are backlight bleed on an LED or LCD panel, or IPS glow on an IPS one. A little is normal; large bright clouds are a defect worth returning. Give your eyes a minute to adjust to the dark before you judge it.

Colour banding is visible steps between shades that should blend smoothly. Viewing the grayscale steps in this test, or any gradient, makes banding easy to see. It usually points to a lower bit-depth panel, such as 6-bit with dithering rather than true 8-bit, or to an aggressive contrast or sharpness setting. Turning off dynamic contrast and picture enhancements often reduces it.

The monitor test uploads nothing and needs no install. It runs entirely in your browser, with no account, no download and no data leaving your device. Once the page has loaded it keeps working offline, which helps when you are testing a machine that is not set up yet. For a single flat field, the plain white screen and color screen pages do the same job in one click.