Green Screen Test
Light only the green subpixel — the channel your eye reads most sharply.
Only the green subpixel is lit. Your eye resolves more detail in green than in red or blue, so faults usually show here first.
Looking at the whole screen, including the corners — what did you see?
How this test works
The page fills the display with pure green, lighting only the green subpixel of every pixel. Green matters more than the other two channels here: human vision resolves far more detail in green than in red or blue, and green carries most of the perceived brightness of an image. That makes a green fill the most sensitive of the three single-channel tests — a fault that is hard to spot on blue is usually obvious on green. The test reports how much of the panel it actually covered and interprets what you report, separating a subpixel fault from a dead pixel.
What the results mean
- Dark dot
- The green subpixel at that spot is not being driven. Because green carries most of the perceived brightness, this is the most visible of the three subpixel faults in normal use.
- Even fill
- No visible variation means the green channel is being driven consistently across the panel.
- Blotches
- Uneven green across the field is a uniformity characteristic rather than a fault in any one pixel.
Common problems and fixes
- Green looks much brighter than red or blue did
- That is your eye, not the panel. Human vision peaks in the green part of the spectrum, so an equal-intensity green reads as considerably brighter than an equal-intensity red or blue.
- I am looking for a green screen for video
- This is a display test, not a keying backdrop. A monitor showing green is the wrong tool for chroma key — the brightness is uneven and the panel reflects your subject.
- A speck shows here that white did not
- Expected. Green is the most sensitive of the single-channel fills, so it is often the first place a subpixel fault becomes visible.
Frequently asked questions
Why do faults show up on green first?
Because your eye is most sensitive to green. Roughly two-thirds of perceived luminance comes from the green channel, so the same physical defect is simply easier to see against green than against red or blue.
Can I use this as a chroma key background?
Not usefully. Keying needs an evenly lit matte surface; a monitor is glossy, unevenly lit across its area, and reflects whatever is in front of it. Use fabric or paper for keying.