Pick a color, then start full screen. On each color look for dots that stay lit, dark or a different color. In full screen the arrow keys or Space change the color; Esc exits.
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How to use and interpret Full Screen Color Test (White, Black, Green Screen)
Use this full screen color test (white screen, black screen, green screen and more) to find dead, stuck or off-color pixels on a monitor, laptop or phone. It also works as a simple full-screen color picker.
How to run the test
- Wipe the screen and set brightness to maximum.
- Pick a color and press "Start full screen".
- Look closely at the whole screen on each color; use the arrow keys or Space to change color.
- Note any dot that stays black on a bright color or bright on black, then press Esc.
What this test checks
Fills the screen with a single color so dead, stuck or off-color pixels become visible.
Look for dead or stuck pixels with full-screen white, black, green and other colors.
How to interpret the result
Use the visual or timing result as an initial screen check. Repeat the test fullscreen and at the display’s normal resolution for the most useful comparison.
Browser limitations
Browser tests cannot automatically prove a physical panel defect. Dead pixels, uniformity and backlight issues still require visual confirmation on the actual display.
Which color for which defect
White and light colors reveal black or dark dots (dead pixels). A black screen shows stuck bright pixels and light leakage. Red, green and blue screens catch pixels stuck on a single sub-pixel color. Scan the whole screen carefully on every color.
Prepare before testing
Wipe the screen with a soft, dry cloth, because dust and smudges are often mistaken for dead pixels. Set brightness to maximum, turn off night mode and color filters, and dim the room if you can. Look closely and from different angles.
Troubleshooting by symptom
- I see a tiny dot on the screenWipe first to check whether it is really inside the screen. If it does not wipe off and is black on every color, it is a dead pixel; if it is lit on one color only, it is a stuck pixel.
- Bright patches at the edgesOn a black screen, mild glow at corners is called backlight bleed. Mild bleed is common; if it is strong, contact the manufacturer.
- How many dead pixels are acceptable for a warranty?It depends on the manufacturer and seller and often follows quality classes such as ISO 9241-307. Check the return and warranty terms where you bought it and show the problem with a photo.
- How do I test a phone or TV?Open the page in the device's browser and go fullscreen. On a TV without a browser, connect a computer by HDMI and mirror the screen.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel stays black on every color. A stuck pixel stays one color (red, green, blue or white). Stuck pixels can sometimes be fixed; dead pixels usually cannot.
How do I check for backlight bleed?
Show the black screen in a dark room and look for bright patches at the edges or corners. A little is common; strong bleed can be a warranty issue.
Is a white screen safe for my display?
Yes. A full-screen color is a normal image. Do not leave a bright static screen on for hours.
Can I fix a stuck pixel?
Stuck pixels sometimes recover with gentle pressure or rapid color cycling, while dead pixels usually do not. Do not press hard; the panel can be damaged.
Do dead pixels spread over time?
They usually do not spread on their own, but the same manufacturing or aging issue can produce new ones. Repeat the test a few months apart.
Can the test damage my screen?
No, a solid color is a normal image. Do not leave a bright color on for hours; static images can leave marks, especially on OLED.
Can I test a touchscreen?
Yes, open the fullscreen colors on a phone or tablet. Raise brightness and clean the protective glass.
What does Full Screen Color Test (White, Black, Green Screen) check?
Fills the screen with a single color so dead, stuck or off-color pixels become visible.
Can a browser confirm a dead pixel or panel fault?
It can display controlled test patterns, but the final confirmation is visual because the browser cannot inspect the physical panel itself.
What should I do if the result looks bad?
Repeat the test under the same conditions, check the suggested next diagnostic and compare with another browser, connection or device where practical. Use the related guides for step-by-step troubleshooting.