For night vision, brightness matters more than the colour.
Red at full brightness in a dark room is still a lot of light. Turn the display down as far as it goes before you rely on it. A dim red is what preserves dark adaptation, not red on its own.
Full Screen Red Display
Turn your entire screen pure red with one click. Red is the field for keeping your night vision while you use a screen in the dark, for checking the red sub-pixels on their own, and for red lighting in photos and video.
F for fullscreen, Esc to exit
What the red field is for
Night vision
The rods your eyes use in the dark are least sensitive to long-wavelength red light, which is why astronomers use red torches. A dim red screen lets you see what you need without resetting your dark adaptation.
Red sub-pixel check
This field lights only the red sub-pixels. A dead red sub-pixel shows as a dark dot, and a stuck green or blue one shows as a different-coloured dot.
Photo and video lighting
A monitor makes a large, even red light for portraits, product shots, or a background wash. Brightness is your intensity control.
Darkroom-style working light
A dim red field is enough to find things on a desk at night without the glare of white.
Field notes
Red on its own tests a third of each pixel.
Every pixel is three sub-pixels. This field lights one of them, so it can clear the red sub-pixels and nothing else. Run green and blue as well, or the dead pixel test, which cycles all of them.
Written by Piero Nanni. If a panel of yours behaves differently, tell me and I will correct it. Updated .
Questions
Why use a red screen for pixel testing?
A pure red field lights only the red sub-pixel in every pixel. A dead red sub-pixel shows as a dark dot, and a stuck green or blue sub-pixel shows as a dot of the wrong colour. Check green and blue too to cover the rest.
Does red light really preserve night vision?
Yes, if it is dim. Rod cells, which handle low-light vision, respond least to long-wavelength red light, so astronomers and pilots use dim red lighting. A bright red screen still dazzles, so turn the brightness right down.
Can I use this as a red light for photography?
Yes. Put the monitor beside or behind your subject and use the display brightness as the intensity control. Set the camera white balance manually, or auto white balance will try to neutralise the red.
Download as an image
The same #FF0000 field as a PNG, for a wallpaper, a slide or video background, or a TV that plays images from a USB stick. Made in your browser; nothing is uploaded.
Other colors
Any other colour: use the picker on the homepage.
Screen tools
- White Screen Test Check a white field for dust, dead pixels, uniformity, and tint.
- Dead Pixel Test Cycle white, black, red, green, and blue to find faulty pixels.
- Stuck Pixel Fixer Rapidly flash colors over a stuck pixel to try to un-stick it.
- Backlight Bleed Test Spot light leaking around the edges of an LCD panel on black.
- Screen Burn-In Test Reveal retained images and uneven wear on OLED and plasma panels.
- Monitor Test Full sweep: pixels, bleed, uniformity, and color channels.
- Light Box Use the screen as a tracing panel or soft photography light.