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About this tool
Locate dead or stuck pixels using full-screen solid color test patterns.
The Dead-Pixel Screen Test fills your entire display with a sequence of five solid colour fields — dark, red, green, blue and light — so any pixel that stays black, stays lit, or shows the wrong colour becomes obvious against a uniform background. You click or tap anywhere to advance to the next pattern and press Exit test to return. It is the standard check to run on a new monitor, laptop or phone during the return window, and on a used screen before you hand over money.
Open Dead-Pixel Screen Test on AltFTool — it loads instantly in your browser.
Press Start test — the tool requests no camera, location or motion permission and records nothing — and the first colour field fills the entire screen.
Click, tap, or press Enter or Space anywhere to advance through the five patterns — dark, red, green, blue, then light — scanning the whole panel including the corners on each field.
Note any pixel that stays black, stays lit or holds the wrong colour through every field — that identifies the faulty sub-pixel — then press the Exit test button or Escape to return.
Dark, red, green, blue and light cycle on a single click, so you can sweep the whole panel through every primary without hunting for controls.
The pattern covers the entire viewport with nothing but an exit button, so no chrome or borders hide a defect near the edge of the panel.
A pixel that vanishes on the red field but shows on green tells you which sub-pixel is failing, which is exactly what a warranty claim needs described.
A dead pixel receives no power and stays black on every pattern, including the white field. A stuck pixel stays permanently lit in one colour — it shows up as a bright red, green or blue dot on the dark field and often disappears on the field matching its own colour.
Run the display at its native resolution, clean the screen first so dust is not mistaken for a fault, view each of the five colour fields full screen, and scan the whole panel including the corners. Looking from about arm's length rather than pressed against the glass matches how manufacturers assess defects.
A truly dead pixel cannot be repaired outside a panel replacement. A stuck pixel sometimes recovers with rapid colour-cycling software or gentle pressure, though neither is reliable and pressure can damage the panel — a warranty exchange is the dependable route.
It varies by manufacturer and panel class rather than following one universal number — many consumer policies only replace a screen once several bright or dark sub-pixels are present, while premium or zero-bright-dot warranties replace on the first one. Check the specific defect policy for your model before assuming a single pixel qualifies.