Green screen
A full screen of pure green, driving the green sub-pixel to maximum while red and blue stay completely off.
Esc to exit · arrow keys to change · H hides the controls
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 green screen is for
The most revealing primary
Human vision is most sensitive to green, and the sRGB and Rec.709 standards encode that directly: when luminance is calculated from the three primaries, green contributes about 0.7152 of it, against 0.2126 for red and 0.0722 for blue. In practice that means a full green field is by far the brightest of the three primaries, and brightness is what makes small defects visible. A dead or dim element shows as a sharper, higher-contrast dot on green than on red or blue, so if you only have time to run one primary, run this one.
Seeing panel unevenness
Because green carries most of the visible brightness, it is also the primary where variation across the panel is easiest to notice. Sweep your eyes slowly from one side to the other and look for regions that seem to sit at a different level, or a faint texture across the field. Mura, banding and clouding all tend to be more legible here than on a red or blue field, though a mid grey remains the definitive field for uniformity work.
Not a chroma key background
This is worth saying plainly, because the phrase leads people here: a pure green display is not a usable chroma key backdrop. Video keying relies on a large, evenly lit, matte surface behind the subject, and a monitor is a small, self-illuminating, specular object that produces glare and colour spill on skin and hair. If you need a keying background, use fabric or paint. If you need to test how your keying software handles a green input, this page will do fine.
Checking green tint on laptops
A green cast across an otherwise neutral image is a known annoyance on some laptop panels and on phones with uneven display calibration. Loading a full green field will not show you the cast, but it does confirm the green channel is reaching full output. Pair it with the white screen, where a cast is actually visible, and compare against a second device.
How to run this test
- Go full screen. Turn your brightness down a little if the field is uncomfortable, because green is the brightest primary.
- Sweep the panel in bands, looking for black dots against the bright green.
- Take a second pass for wider variation in brightness across the field, which points at uniformity rather than a pixel fault.
- Follow with the red and blue fields to cover the other two elements.
What a problem looks like
- Dark dots on green
- A failed green element. These are the easiest sub-pixel faults to spot of the three, because green is the brightest primary and the contrast against a dark dot is highest.
- Visible banding
- Horizontal or vertical bands of slightly different brightness usually point at panel uniformity rather than a pixel problem. The uniformity test with a grey field will show it more clearly.
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
Why is green the best colour for finding dead pixels?
Green contributes roughly 71 per cent of perceived luminance in sRGB, against 21 per cent for red and 7 per cent for blue. A full green field is therefore the brightest single-primary field available, and a dark dot against a bright field is the easiest defect to see.
Can I use my monitor as a green screen for video calls?
No. Chroma keying needs a large, matte, evenly lit surface behind you. A monitor is small, glossy and emits its own light, which produces glare and green spill onto skin and hair that keying software cannot cleanly remove.
My green looks yellowish or lime. Is that a fault?
Usually not. Wide-gamut displays render sRGB green outside its intended coordinates unless colour management is applied, and warm-light features shift the whole picture. Compare against another screen before drawing conclusions.