Screen Test: Dead Pixels, Colors & Banding
Check a display for stuck or dead pixels, uneven backlight, colour casts and gradient banding. Start the test to fill the screen with a colour; click, press Space or use the arrow keys to move between panels, and press Escape to leave.
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About this tool
The test shows solid black, white, red, green, blue and gray panels and a black-to-white gradient, one after another, full screen. Your own eyes do the judging: you look for dots that never change colour, bright edges on black and visible steps in the gradient.
It cannot measure brightness, contrast or colour accuracy, and it cannot fix a faulty pixel. The panels do not flash, but take a break if you feel eye strain.
How to read the results
- A stuck pixel stays one colour (often red, green or blue) on every panel. A dead pixel stays black on the white panel.
- Dust looks like a dead pixel on white and black, so clean the screen first. A dot you can wipe off is not a pixel.
- Backlight bleed shows as lighter patches along the edges on the black panel in a dim room.
- Banding shows as visible steps in the gradient. A little is normal; strong bands point to limited colour depth or aggressive display processing.
Frequently asked questions
Can a stuck pixel be fixed?
Sometimes. Gentle pressure or a pixel-exercising video can free a stuck pixel, but a dead pixel usually cannot be repaired. Check your warranty's pixel policy.
How many dead pixels are acceptable?
It depends on the manufacturer's policy, which often allows a few. Look it up before you contact support.
Why is the black panel not fully black?
LCD panels use a backlight, so black is a dark gray. OLED panels switch pixels off and look much blacker.
Does fullscreen matter?
It helps, because browser bars hide the edges of the screen. If fullscreen is blocked, the panel still fills the page.
Will it damage my screen?
No. It simply shows solid colours.
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