Red Screen
Red is one of the three primary colours used in monitor dead-pixel tests. Because a stuck subpixel often fails to light only one channel, a full red screen will reveal a dead red subpixel that white or grey backgrounds hide. It is also the classic safelight colour when you need dim illumination.
What this colour is good for
- Revealing dead or stuck red subpixels that a white screen can mask.
- Dim red lighting in a darkroom, at night, or around a telescope.
- Colour reference when matching a red in print, paint, or video.
Pure #FF0000 is very saturated. Judging print colour against an uncalibrated screen will mislead you — use a physical swatch if accuracy matters.
Frequently asked questions
Why test with red instead of just white?
A white test lights all three subpixels at once, which can hide a fault in a single channel. Cycling red, green and blue isolates each subpixel, so a dead red subpixel shows up as a black dot on the red screen.
Is red light better for night vision?
Long-wavelength red interferes least with dark adaptation, which is why darkrooms and observatories use it. Keep the brightness low — a bright red screen still costs you dark adaptation.