White Screen & Color Screens

How to use the white screen

1. Pick a color. White is selected by default.
2. For any other shade, use the color picker or type a hex code like #FFE6CC.
3. Move the brightness slider if you want a dimmer color.
4. Click Full screen or the preview. The hint and the cursor fade after a moment.
5. Press ← or → to switch presets, and Esc to exit. On a touch screen, tap to show the Exit button.

What a white screen is good for

• A light for video calls and photos: a white screen in front of you works as a soft fill light. Warm white and cool white change the tone.
• Cleaning your screen: switch between white and black. Dust, smudges and streaks show up against one or the other, depending on your screen's finish and the room light.
• Checking brightness and color evenness: on white and gray, look for darker corners, patches or a tint that changes across the screen.
• Finding dead pixels: a dead pixel is a black dot on white. The dead pixel test cycles through every color you need.
• Tracing: lay thin paper over a tablet showing white and use it as a light box.
• A black screen on OLED: OLED pixels switch off on black, so the screen gives off no light.

How the brightness slider works

The slider scales each color channel. At 50%, white (#FFFFFF, or 255, 255, 255) becomes#808080 (128, 128, 128), because 255 × 0.5 = 127.5, which rounds to 128. It changes the color, not your screen's backlight. For the brightest light, set the slider to 100% and turn your device's brightness up.

Full screen mode uses your browser's Fullscreen API, and the Screen Wake Lock API keeps the display from going to sleep while it's open. Nothing is uploaded: the page runs entirely on your device.

Preset colors and their codes

To check your screen for light leaking at the edges, use the screen bleed test. To see your resolution and pixel ratio, try What Is My Screen Size?