Dead Pixel Test

Features

• Eleven solid slides: black, white, red-green-blue, cyan-magenta-yellow and three greys
• ⚠️ Black comes first, because stuck pixels show only on dark backgrounds and they are the common case
• The primaries are separate so a specific subpixel can be located
• Three grey levels for panel uniformity, vignetting and tint
• Full-screen display, so the browser chrome cannot cover the area under test
• Space or the arrow keys for the next slide, Esc to leave; the overlay closes with the full-screen state
• Click a swatch to jump to one colour and enter full screen directly
• Everything runs locally; no network requests and no reading of your screen

How to use

1. Clean the screen first; dust and fingerprints are read as dead pixels
2. Press Start full screen, or click a swatch to go straight there
3. Step through with Space or the arrow keys, close up and in bands
4. Press Esc to exit

FAQ

What is the difference between a stuck and a dead pixel?

A stuck pixel stays lit or frozen on one colour and is most visible on dark, especially black, backgrounds. A dead pixel never lights up and shows on white or bright backgrounds, which is why black comes first and white second: testing only one of them misses half the cases. Also worth knowing: a single bad point is a pixel fault, while a whole row or column of them is more likely a ribbon cable or driver board, so check before replacing the panel.

Why clean the screen first?

Because dust, fingerprints and dried specks look exactly like dead pixels: a small patch of colour that does not change. That is the most common false positive in this kind of test, and it turns a perfectly healthy panel into three dead pixels you think you have found. Cleaning takes seconds.

What are the primary colour slides for?

Each pixel is made of red, green and blue subpixels and they fail separately. A stuck red subpixel is invisible on white, because the other two still work, but shows as a dark point on the red slide and as a bright one on green or blue. Locating a fault at subpixel level therefore needs all three, which is why black-and-white alone is not enough.

Can a dead pixel be fixed?

Mostly no, but it is worth trying a pixel refresh once: rapidly switching a patch between black and white can sometimes unstick liquid crystal, and it works more often for stuck pixels than dead ones. ⚠️ It cannot repair physical damage. If the panel is under warranty and enough pixels are affected to pass the manufacturer policy, you can usually ask for a replacement, and those policies count bright and dark defects separately, which is why this tool shows you the two kinds apart.