Blue Screen

How to use the blue screen

1. Press Open full blue screen. The whole screen turns blue and the mouse pointer hides after a moment.
2. For a pixel check, use Pure blue at full brightness and look closely: blue looks darker to the eye than red or green, so take your time.
3. Pick another shade from the swatches for a softer light or a chroma key backdrop.
4. Press Esc, or tap the screen on a phone, to come back to this page.

What the results mean

Pure blue (#0000FF) lights only the blue subpixel of each pixel. A healthy panel shows one even, deep blue everywhere. Look for:

• A black dot: the blue subpixel there is dead. If it is also black on the white screen, the whole pixel is dead.
• A red, green or white dot: another subpixel is stuck on. The stuck pixel fixer can sometimes revive it.
• Dim or purple-tinted areas: on an older OLED, the blue material ages fastest, so worn areas (such as where a taskbar or keyboard sat) can look dimmer. The burn-in test checks this in more detail.

Test the red and green screens too, or run the dead pixel test for every color in one go.

What a blue screen is used for

Pixel checks. Blue is the third of the three single-channel tests. A dead blue subpixel is easy to miss on white, so a full blue screen is the only reliable way to find one.

OLED aging. Blue OLED pixels wear out faster than red and green ones. On a phone or TV that is a few years old, a blue screen shows uneven wear more clearly than any other color.

Backdrop and light. Chroma key blue (#0047BB) is used when the subject is green or wears green. A monitor showing it works as a small backdrop for close-ups. Blue also makes a cool, calm ambient light, but avoid bright blue light late at night, because it affects your body clock more than warm light.

Not the blue screen of death. If your Windows PC crashed to a blue error screen, that is a system crash, not a display fault. See the fixes below.

Common problems and fixes

My PC shows a blue error screen (BSOD)

Write down the stop code shown on the screen (for example MEMORY_MANAGEMENT or IRQL_NOT_LESS_OR_EQUAL) and search for it on Microsoft's support site. Common causes are a faulty driver, a recent update, failing memory or storage. Start with Windows Update and your graphics driver, and run Windows Memory Diagnostic if it keeps happening.

The blue looks purple or too dark

Turn off night mode, Night Shift or blue light filters, which cut blue the most, and use the monitor's standard or sRGB mode. Blue always looks darker than red or green to the eye; that is normal.

Full screen does not work on my iPhone

iPhone Safari does not let websites go fully full screen, so the blue fills the browser window instead. Rotate to landscape or add the page to your home screen.