Dead Pixel Test

Full-screen solid colours that reveal dead and stuck pixels

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About this tool

Fill the screen with red, green, blue, white, black and gray to hunt for dead pixels. Against a flat colour a single misbehaving pixel jumps out, so checking a new monitor or a second-hand laptop takes about five minutes. Gradient screens are included too, so you can also judge whether colours blend smoothly and whether any area looks blotchy.

How to use

  1. Decide whether to use the auto cycle, then tap a colour to enter full screen.
  2. Sweep your eyes slowly across the whole screen looking for dots of a different colour.
  3. Click or use the arrow keys to change colour and check the same spot against several backgrounds.
  4. Press ESC when you are done.

Frequently asked questions

What is the difference between a dead pixel and a stuck pixel?
A dead pixel gets no power and stays black whatever you display. A stuck pixel is frozen on one colour, so it shows as a red, green or blue dot on black. Stuck pixels sometimes recover; dead ones usually need repair or replacement.
Can a stuck pixel be fixed?
Rapid colour changes sometimes free a frozen pixel. Set the auto cycle to two seconds and leave it running for a few hours. It does not always work, and pressing on the panel with your fingers is not recommended because it can damage the display.
There is a dot but I cannot tell if it is a pixel or dust.
Wipe the spot with a soft cloth and look again - if it comes off, it was surface dust. Tilting the screen slightly also helps: a mark that shifts with the angle sits on the surface, one that stays put is inside the panel.
Full screen does not work.
Some browsers, iOS Safari among them, do not allow arbitrary elements to go full screen. The colour layer still covers the page, so you simply lose the strip behind the address bar and the test still works.

Replacement policies differ by manufacturer and usually require more than a set number of defective pixels, so check with your seller first. This tool only displays colours: it does not scan or repair the panel, and nothing is sent to a server.

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