How to use the red screen test
- Dim the room lights and set your screen brightness to maximum.
- Press Pure red to fill the whole screen with solid red.
- Scan the panel slowly from corner to corner for any dot that is not red, such as black, yellow, pink or white.
- Wipe the screen and look again if you see a faint mark, because dust and fingerprints look like stuck pixels.
- Press Esc, then try Deep red and check that the shade stays even across the panel.
- Tap anywhere or press Esc to exit.
What a red screen shows
| What you see | Likely cause | What to do |
|---|---|---|
| A black dot | Dead red subpixel, or a fully dead pixel | Run the White Screen Test. If the dot stays black on white too, the whole pixel is dead. |
| A yellow dot | Green subpixel stuck on | Gentle massage or a color cycling video sometimes frees it. Note the position first. |
| A pink or magenta dot | Blue subpixel stuck on | Check the same spot on the Green Screen Test to confirm which subpixel it is. |
| A white dot | Green and blue subpixels both stuck on | This is a stuck pixel. Compare its position on each color. |
| One area looks orange or pinker than the rest | Uneven color uniformity or a tint | Mild unevenness is common on LCDs. Judge it at your normal brightness. |
| A faint ghost of a past image | Image retention or OLED wear | Run a full screen of changing colors for a few minutes and test again. |
Who this is for
- Buying a used monitor, phone or TVA red fill exposes stuck green and blue subpixels that a busy home screen hides. Check before you pay.
- Just unboxed a new displayLook for off-color dots while the return window is still open.
- OLED phone ownersRed is where uneven wear and image retention often show first, so check it after a year or two of use.
- Photographers and video editorsConfirm that red is even across the panel before color critical work.
- Repair techniciansPin down which subpixel has failed so you can decide between a panel swap and a cable check.
- Anyone filing a warranty claimDocument a stuck or dead subpixel on a clean, uniform background.
Frequently asked questions
Why test with a red screen instead of just a white one?
White lights every subpixel at once, so it shows dead pixels well but can hide a subpixel that is stuck on. A red fill turns the green and blue subpixels off, so one that is stuck on shows up as a yellow, pink or white dot you would never notice on white.
What does a dead red subpixel look like?
On a red fill it appears as a small black dot, because that subpixel cannot light up. The same pixel still glows normally on green and blue screens, which is how you tell a single dead subpixel from a fully dead pixel.
How can I tell a stuck pixel from dust on the screen?
Dust and fingerprints usually look fuzzy and can be wiped away. A stuck pixel is a sharp, tiny square of one color that stays in exactly the same spot when you wipe the screen and when you change the fill color.
My whole screen looks orange or pink instead of pure red. Is it faulty?
Often it is a setting, not a fault. Night light, true tone, color profiles and low power modes shift colors. Turn them off for the test. If one part of the panel is clearly different from the rest, that points to a panel uniformity problem.
Why does the red look a little different on my phone and my monitor?
Panels differ in how saturated their reds are, and phones with wide gamut OLED screens show a deeper red than a standard monitor. The test is about evenness and stray dots, not about matching one exact shade.
What is the Deep red option for?
A dark red fill makes gentle shading differences, banding and weak subpixels easier to judge at a lower light level. Switch between Pure red and Deep red and compare how evenly the panel behaves.
Can a red screen test damage my display?
No. Showing a solid red image for a minute or two is normal use and no different from a red web page. Avoid leaving any static image on an OLED for hours, which is true of every image.
What should I do if I find a stuck pixel?
Note its color and exact position, then run the White, Green and Blue tests to see how it behaves. Check the warranty policy, because many makers only replace a panel above a set number of faulty pixels.