Green Screen Test: Check Green Pixels and Green Channel Banding Online
Press F and this page floods your display with pure #00FF00 — the loudest color a monitor owns. Green carries the largest share of perceived brightness of the three primaries, which cuts both ways: it is the channel where banding, unevenness and dead subpixels show up first and most obviously, and it is also the exact shade filmmakers rely on for chroma-key backgrounds.
What a full green screen reveals
Press F for fullscreen and sweep the field slowly. A pure green screen drives only the green subpixels, so any pixel staying black carries a dead green subpixel, and one glowing red or blue has a stuck one — triage the suspect the same way you would on the red field. Because your eye weighs green more heavily than red or blue, texture problems surface here before anywhere else: watch for soft blotches, faint stripes and corners that shade darker, and confirm what you see against the stepped ramps of the grayscale page. If the field looks yellowish or bluish rather than convincingly green, the panel’s channel gains are out of balance — the color calibration page will sort out whether it is a setting or the panel.
The same logic explains the film-world connection. Chroma-key studios paint backdrops green because digital cameras record green with the highest resolution and lowest noise, and because the color is far from every skin tone. Your screen is showing the reference shade of that workflow — useful if you edit video and want to eyeball how your own backdrop compares, or simply a neat way to explain to someone why weather presenters never wear green.
Practical uses and what to do about flaws
Beyond defect hunting, full green is a deliberate eye-of-the-beholder test: since green dominates perceived brightness, a display with a weak or drifting green channel looks dim and muddy long before other colors complain. Editors and photographers use the solid field to check that an ICC profile or monitor preset has not pushed green, and gamers notice here first when a panel’s color drifts with heat. It is also the honest background for judging how your camera sees your display — green fields expose moiré and shutter artifacts on video better than most.
As for the defects: a dead green subpixel is permanent — pixels that stay black on this field will do the same in every greenish scene, casting a faint magenta tint over anything that should be neutral. Stuck green dots deserve a few runs of the stuck pixel fixer before you declare them dead; the dead pixel page explains how to classify and document either fault for warranty. Small green blemishes stand out far more here than in normal content, so judge severity on real material before demanding an exchange, and finish the survey with the all-in-one screen test to see how the green channel behaves across every other solid color.
Frequently Asked Questions
What is a green screen test for?+
It fills the display with pure green to expose dead or stuck green subpixels and to reveal banding and unevenness in the green channel, which shows defects first because green dominates perceived brightness.
Why does green show banding before red or blue?+
Perceived brightness comes mostly from the green channel, so any stepping or clouding in green hits your eye hardest. Defects that are barely visible on red or blue fields stand out immediately on green.
Is this the same green used for chroma key?+
It is the same pure #00FF00 family that chroma-key backdrops reference. Studios choose green because cameras sample it with the most detail and it is distant from skin tones.
A pixel stays black on green — what now?+
Its green subpixel is dead, which tints neutral content slightly magenta. Try the stuck pixel fixer in case the subpixel is merely stuck; if it stays black, document it as a dead pixel for a warranty claim.