Red Screen Test
A pure red full-screen exposes stuck pixels and dead subpixels that only show on red, and lets you judge how evenly your panel renders the red channel. Click to go fullscreen, Esc to exit.
Click the button to fill your entire screen with solid red. Click anywhere or press → to cycle colours, and Esc to exit.
Why test a red screen
Each pixel is made of red, green and blue subpixels. A fault in just one subpixel only shows on a matching solid colour:
- On a red field, a dead red subpixel appears as a tiny black or off-colour dot, and a subpixel stuck off shows against the uniform red.
- Stuck pixels lit on other colours stand out sharply against pure red.
- Blotchy or uneven red can reveal panel banding or a failing colour channel.
Stuck pixel check
Stuck pixels differ from dead ones: a stuck pixel is permanently lit on one colour, while a dead pixel stays black. Cycling through red, green and blue is how you tell which subpixels are affected. A pixel that looks black on red but normal on green and blue has a dead red subpixel. Our guide on dead pixels vs stuck pixels explains the difference in full.
Trying to revive a stuck pixel
Stuck pixels sometimes recover. Rapidly cycling solid colours over the area — flicking between red, green and blue — can nudge the subpixel back to life, and gentle pressure with a soft cloth over the spot (screen off, then on) occasionally helps. Dead pixels, which are unpowered, cannot be revived this way.
Complete the check
Red is one of three colour passes. Follow with green and blue, then white and black — or run all of them at once with the full dead pixel test.
Frequently Asked Questions
What does a red screen test find?
It reveals stuck or dead subpixels that only show on red — a dead red subpixel looks like a small dark dot, and pixels stuck on other colours stand out against the uniform red. It also shows red-channel banding.
What is the difference between a stuck and a dead pixel?
A stuck pixel is permanently lit on one colour; a dead pixel stays black because it gets no power. Cycling red, green and blue tells you which subpixels are affected.
Can I fix a stuck pixel?
Sometimes. Rapidly cycling solid colours over the area, or gentle pressure with a soft cloth while toggling the screen off and on, can revive a stuck pixel. Dead pixels cannot be revived.
Why test red specifically?
Because a fault in the red subpixel only becomes visible on a solid red field. On mixed content it blends in. The same logic applies to the green and blue passes.
How do I exit the red screen?
Press Esc to leave fullscreen, or click to cycle to the next colour. You can switch to any colour with the buttons before going fullscreen.
Should I run the full dead pixel test?
Yes. Red is one colour pass. The full dead pixel test cycles red, green, blue, white and black so you catch every stuck and dead pixel in one go.