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Dead Pixel & Monitor Test
Full-screen colours and patterns to find dead pixels, check uniformity and see motion blur.
Free tools that run in your browser. Nothing you type, open or create is uploaded to NerdBible or anyone else.
Arrow keys, Space or a click step through the patterns. Escape leaves full screen.
Black
Dead, stuck and hot pixels
A dead pixel stays black whatever the screen shows, so it is easiest to spot on the white, red, green and blue screens. A stuck pixel stays lit in one colour, usually red, green or blue, and stands out on the black screen. A hot pixel stays white and also shows up on black.
Clean the screen first, since dust looks a lot like a dead pixel; dust moves when you wipe it, a pixel does not. Many manufacturers only replace a screen under warranty when it has a certain number of faulty pixels, so check the policy for your model and note where each one is.
How to use it
- Choose a test: solid colours, gradients, uniformity or motion.
- Press Start full screen. Step through the patterns with the arrow keys, Space, or a click or tap.
- Look closely at the whole screen on each pattern, then press Escape to leave full screen.
Questions
What does the gradient test show?
Smooth gradients should fade without visible steps. Clear bands of colour, called banding, come from limited colour depth or from processing in the screen or graphics settings.
What does the uniformity test show?
On a flat grey or dark screen, brighter or darker patches, a tint in one area, or light leaking at the edges show uneven backlighting, which is common in LCD screens to some degree. Check it in a dim room.
What does the motion test show?
A block moving at a set speed shows how much the screen smears or ghosts moving images. A sharper edge means less motion blur. Try each speed; faster speeds show the difference more.
Why does full screen not work on my iPhone?
iPhone browsers do not let pages go full screen, so the test fills the browser window instead. Turn the phone sideways and hide the address bar by scrolling for the largest view.