Black screen, full screen, one click

What is blackfullscreen?

A set of small tools that do one thing: turn your display into a single flat color, immediately, with no app and no account. The color is drawn by your browser, so nothing is uploaded and nothing is stored. It works on a monitor, a laptop, a tablet or a phone, in any modern browser.

A plain colored screen is more useful than it sounds, which is why so many people search for one. It is the quickest way to inspect a panel, the cheapest soft light you will ever have, and a clean backdrop when you need one in a hurry.

What people use a full screen color for

Finding dead and stuck pixels

A dead pixel receives no power and stays black no matter what the display is showing, so it only becomes visible against a bright field. A stuck pixel is the opposite: it is locked on in one color and shows up as a bright red, green or blue dot against solid black. Cycling through black, white, red, green and blue full screen is the standard way to find both, and it is exactly what the dead pixel test automates.

Checking backlight bleed and uniformity

On an LCD the backlight is always on, even when the panel is showing black. Where the seal around the edge is imperfect, light leaks through and you see pale patches or corners glowing against a dark image. A full black screen in a dark room makes this obvious. For general uniformity a mid grey screen is better still, because it drives every subpixel equally and reveals clouding and tint that a black or white field can hide.

Saving battery on OLED and AMOLED

OLED and AMOLED displays light each pixel individually, and a black pixel is simply switched off. A black screen therefore draws close to no power on those panels, which is the reason dark mode genuinely extends battery life on a modern phone. On a conventional LCD the backlight stays lit regardless of what is on screen, so the saving is negligible. If you are unsure which you have, a black screen at full brightness in a dark room tells you: an OLED goes properly black, an LCD glows faintly grey.

Cleaning a monitor

Dust and smears are almost invisible against a bright desktop. A black screen makes dust and fingerprints stand out; a white screen reveals the darker marks that black hides. Most people use both, one after the other. Turn the display off first if you are using any liquid.

Lighting a shot

A white or warm-toned screen turns any monitor, tablet or phone into a soft, even light source. Photographers and people on video calls use it as an improvised fill light, and a warm orange screen works as a rough substitute for a warming gel when you are trying to match indoor lighting.

Chroma key backdrops

Green is the chroma key standard because human skin contains very little green, so keying it out leaves clean edges. Blue is the usual alternative when your subject is wearing green or has blond hair, which picks up green spill badly. A second screen filled with a green screen gives you a small backdrop for free.

Presentations, streams and getting attention

A plain black screen is the fastest way to blank a projector without hunting for the remote, and it is what people reach for when a slide deck needs to disappear for a moment. If you need the opposite, the text on screen tool puts a large message across the whole display, which carries across a room far better than anything you can shout.

Reducing eye strain and getting to sleep

A bright white page in a dark room is a common cause of tired eyes at night. A dark or dimmed screen produces far less light and is easier to look at for long periods. Some people leave a black screen running instead of turning a display off entirely, so a monitor stays awake without lighting the room.

How to test your screen in about a minute

Turn the brightness up, darken the room, and take each color full screen in turn. You are looking for four things.

Dots that do not match. A colored dot on black is a stuck pixel; a black dot on white is a dead one. Patches of uneven brightness. Best seen on grey. Light leaking from the edges or corners. Best seen on black in a dark room. A color cast. A white screen that looks yellow, pink or blue usually means the panel is ageing or the color temperature is set oddly.

Check the warranty before you worry. Most manufacturers only replace a panel once a certain number of dead pixels appear, and a single stuck pixel will rarely qualify. Stuck pixels can occasionally be freed by cycling colors quickly for a few minutes. Dead pixels cannot be fixed in software by any tool, including this one.