TestDock

Red screen

One click fills the display with red. Choose pure red for testing, or a dim red for low-light use where white light would be too bright.

The colour fills the whole screen. Press Esc or the Exit button to leave.

Or open a single colour:

What a red screen is useful for

  • Low-light use: astronomers, photographers and campers use dim red light because it disturbs dark-adapted vision less than white light. Use the darkest shade and lower the screen brightness as far as it goes.
  • Checking red sub-pixels: on pure red, a dark dot is a red sub-pixel that does not light. The dead pixel test checks all colours in one sweep.
  • Colour and uniformity: a flat red reveals blotches or tint shifts on some panels.
  • Ambience and video: a solid red background for photos, streams or mood lighting.

Tips

  • On LCD screens the backlight stays on, so even dim red leaks some white light at high brightness. OLED screens can produce darker reds.
  • Turn off night-light or blue-light filters if you need pure red for testing; they do not matter for night use.
  • The screen stays awake while the red screen is open, if your browser supports it.

Questions

Does a red screen protect night vision?

Dim red light is widely used for this because it disturbs dark adaptation less than white light. Keep it as dim as possible; a bright red screen still affects your eyes.

How do I exit?

Press Esc, or move the mouse and press the Exit button in the corner.

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