Yellow screen
A full screen of pure yellow, driving red and green to maximum with the blue sub-pixel completely off.
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Dimming changes what is sent to the panel, so this is no longer an exact colour value. Return the slider to 100% before judging anything.
What a yellow screen is for
Finding a blue sub-pixel that is stuck on
Yellow is the one field where blue is switched fully off while the panel is otherwise at full brightness, and that makes it the specific test for a blue element stuck in the on position. Such a pixel shows here as a small white or pale bluish dot in a field of yellow, and it is genuinely hard to see anywhere else: on white it blends in, on blue it is indistinguishable from its neighbours, and on black it is a faint speck. If someone has told you they can see a white dot only on certain backgrounds, this is the field that confirms it.
A bright field without the blue
Yellow is close to the brightest colour a display can produce, because it combines the two primaries that carry most of the perceived luminance. That makes it useful as a second high-brightness field after white, with the added property that any blue contribution stands out immediately. It is also a reasonable field for spotting surface dust, for the same reason white is, while giving you the sub-pixel information white cannot.
Checking warm-light features
Night Shift, Night Light and similar features work by reducing blue output. On a yellow field blue is already at zero, so switching a warm-light feature on and off should change this page very little, while it visibly changes a white field. That makes the pair a quick way to confirm what a warm-light setting is actually doing to your display, which is useful if you suspect one is stuck on.
Legibility and high-visibility contrast
Yellow against black is the highest-contrast colour pairing in common use, which is why it appears on road signs, safety equipment and machinery. If you are checking how readable an interface is on a particular panel, or how a display behaves with saturated warning colours, a full yellow field is a fair worst case for glare and for reflected light in a bright room.
How to run this test
- Go full screen. Yellow is close to peak brightness, so set a comfortable brightness first.
- Look for white or pale bluish dots. Those are blue elements stuck in the on position.
- Toggle any warm-light feature on and off. This field should barely change, which confirms what the feature is doing.
- Pair this with the purple field to cover a stuck green element as well.
What a problem looks like
- White or bluish dots
- A blue element stuck on. Yellow is the field that isolates it, since blue should be contributing nothing here at all.
- Greenish or reddish patches
- Regions where the balance between red and green drifts across the panel. Usually a uniformity characteristic rather than a fault, and easier to confirm on a grey field.
What to do next
If something looks wrong, check it again in a normally lit room and from straight on, then check whether it appears on a second device. If it only happens on this screen and you are still inside the return window, that is the time to contact the retailer.
Questions people actually ask
What does a yellow screen test show that white does not?
It switches the blue sub-pixel off completely while keeping the panel bright. That makes a blue element stuck in the on position appear as a white or bluish dot, which is nearly impossible to spot against a white field where blue is supposed to be lit anyway.
Why does my screen look yellow all the time?
Check for a warm-light feature first, then your colour profile. A persistent yellow cast on a laptop that has had heavy use can also come from panel ageing. Compare against a second device on the white screen page before concluding anything.
Is yellow useful for cleaning the screen?
It works about as well as white for surface dust and smears, since both are bright fields. White is marginally better for judging whether a mark is neutral dirt or a coloured defect, because it gives you an unbiased background.