What a yellow screen is used for
- A warm, high-visibility background for signage on a spare monitor
- Checking the red and green channels together while blue stays off
- Warming up webcam lighting that reads too blue
- High-contrast backgrounds for low-vision reading, with black text over it
Yellow screen online: #FFFF00 at full screen
Yellow is red and green at full output with blue switched off entirely, which makes it the brightest single colour most displays can produce — brighter than white on some panels, because white adds blue, and blue subpixels are typically the dimmest of the three.
That brightness is why yellow does signage work. Black on yellow is one of the highest-contrast pairings in ordinary use, which is why it turns up on hazard tape and road signs, and why it works well for anyone reading a screen with reduced vision.
Because blue is fully off, a yellow field is also a quick way to confirm a blue channel fault. If you see any blue tint at all in this screen, something is stuck.
How to get a full screen yellow background
Press the fullscreen button on the player above, or the F key. Escape returns you to the page. On a desktop browser F11 does the same job and hides the browser's own toolbars as well.
The colour box is a control, not a picture: use the hex field to enter any value, pick another shade from the palette, or download the current colour as a PNG at your screen's resolution. Whatever you set is written into the address bar, so the link you copy reproduces exactly what you are looking at.