What a red screen is good for
Red light interferes least with dark adaptation, which is why observatories, darkrooms and submarine control rooms use it. A red screen at low brightness lets you read a display without giving up the night vision it took your eyes half an hour to build.
- Astronomy and night work — read a screen without resetting your dark adaptation.
- Photographic darkrooms — a safelight substitute for handling paper.
- Colour channel testing — checking that a monitor renders red cleanly with no tint or banding.
How to use it
- Press Full screen, or click the icon in the corner of the preview. The colour fills the display and everything else disappears.
- Set the brightness and warmth to suit the room, and turn on Keep awake so the screen does not sleep.
- Press Esc to come back. Your settings stay in the address bar, so the link reproduces this exact setup for anyone you send it to.
Questions
Is looking at a red screen bad for my eyes?
Not inherently, but a bright screen held close for a long stretch causes strain. Drop the brightness slider to around 60% and warm the temperature past 4000K, and look away from the screen every twenty minutes.
Will my screen go to sleep while this is open?
Not if you turn on Keep awake. It uses the browser wake lock, which asks the operating system to keep the display on with no input until you leave the page. It works in Chrome, Edge, Safari and most mobile browsers.
How do I download a red background image?
Open the download panel, pick a format and a size, and the red image is generated in your browser and saved straight away. PNG, JPG and WEBP are available from 1×1 pixel up to 8K, with nothing stored on our side and no watermark.
Does the red screen work on a phone, tablet or TV?
Yes. On a phone or tablet, add the page to your home screen and it opens straight into the red screen. On a TV, open the link in the built-in browser or cast the tab, then use the fullscreen button.
Can I get a screen in an exact shade rather than this red?
Yes. Any hex colour has its own page — put the code after /screen/, so #ff0000 lives at /screen/ff0000. Those links are shareable, so you can send someone the exact colour you mean.
Put this screen on your site
The embeddable version is the screen and nothing else, sized to whatever box you give it.