Dead Pixel Test for Monitors, TVs, Laptops, and Phones
Run a full-screen dead pixel test on a monitor, TV, laptop, tablet, or phone without installing an app.
A dead pixel usually remains black, while a stuck pixel stays lit in one color. Cycle through black, white, red, green, blue, cyan, magenta, and yellow to visually inspect the entire screen.
Full-Screen Color Test
In addition to standard White, Black, Red, Green, and Blue, you can also check with Cyan,
Magenta, and Yellow. Switching background colors makes it easier to spot pixel defects and
display unevenness visible to the naked eye.
*Display range may vary depending on
device/browser settings.
Stuck Pixel Test & Repair
For "stuck pixels" that remain lit in a specific color, applying high-speed color switching
or RGB noise stimulation may improve the temporary control abnormality.
*This is not effective for physical failures
(dead transistors) and may not work on OLED panels.
Mobile & Tablet Ready
Works on major browsers including Windows, Mac, Chromebook, iPhone, iPad, and Android. Use
it to inspect used devices or check your screen before applying a protective film.
*Some mobile browsers may not support complete
full-screen display due to OS limitations.
Screen Uniformity Test
A screen uniformity test displays the same white or gray pattern across the entire screen so you can visually compare the center, edges, and corners. It can help reveal changes in color tint, brightness, or shading on LCD and OLED displays.
Color Uniformity, Brightness Uniformity, and Backlight Bleed
Color Uniformity
Color uniformity describes whether a solid screen keeps the same tint across the panel. Look for areas that appear warmer, cooler, redder, bluer, or more yellow.
Brightness Uniformity
Brightness uniformity describes whether one area looks lighter or darker than another, such as a bright center or dim edges.
Backlight Bleed Test
On LCD monitors, a black screen can reveal light around the edges or corners. OLED displays do not use an LCD-style backlight, so backlight bleed is an LCD-specific issue.
How to Test Screen Uniformity
- Set the monitor to the brightness and picture settings you normally use.
- If possible, let the display warm up and stabilize for a short time.
- Press “Start Uniformity Test.”
- Use the white screen to look for shifts in color tone.
- Move through light gray, mid gray, dark gray, and near-black screens.
- Compare the center, edges, and four corners for changes in brightness or color.
- On LCD displays, use the black screen in a dim room to inspect for backlight bleed.
Gray Uniformity and Dirty Screen Effect
Gray uniformity describes how evenly a display shows the same shade of gray across the entire screen. Use light gray, mid gray, dark gray, and near-black patterns to look for darker patches, tint shifts, or uneven areas.
On uniform gray screens, blotchy or shadowy areas can create a dirty-looking appearance often called the Dirty Screen Effect (DSE). This tool helps you visually inspect for that kind of non-uniformity, but it does not automatically diagnose a panel defect.
Stuck Pixel Repair Tool
Try rapid color changes or RGB patterns on a pixel that remains stuck on one color.
Drag the repair window over the defective area and leave it running for 10-20 minutes.
*This is intended for stuck pixels, not dead pixels. Results vary, and improvement is not guaranteed.
This tool contains flashing lights and high-speed patterns. Do not look directly at the flashing area for extended periods. Use in a well-lit room. If you have a history of epilepsy or photosensitive seizures, please do not use this feature.
Press the "Start Repair" button
to show the repair window here.
*You can drag the box to move it. Press Stop to finish.
Frequently Asked Questions (FAQ)
Q. How do I test for dead pixels?
A. Open the Dead Pixel Test and cycle through black, white, red, green, blue, cyan, magenta, and yellow full-screen colors. Look for pixels that remain black, bright, or stuck on one color.
Q. Does the warranty cover dead pixels?
A. It depends on the manufacturer and the product class. Due to the manufacturing
process of LCD panels, a small number of defective pixels may be considered "within
specification" and not a defect.
Many manufacturers follow ISO standards (e.g., ISO 9241-307) which allow for a certain
number of faulty pixels. However, if the defects are in the center of the screen or if
there are bright "stuck" pixels, some manufacturers (like Dell's Premium Panel Exchange)
may offer a replacement. Check your specific warranty terms.
Q. What is the difference between a Dead Pixel and a Stuck Pixel?
A. A Dead Pixel appears as a black dot because the transistor
controlling it is dead and cannot block light (or let it through, depending on panel
type). Physical failures like this are usually permanent.
A Stuck Pixel (or Hot Pixel) is stuck on a specific color (Red, Green,
or Blue) due to a sub-pixel error. Stuck pixels can sometimes be fixed by rapidly
flashing colors to "massage" the liquid crystals or reset the transistor control.
Q. How do I check full screen on a smartphone?
A. When you tap a check button, the tool attempts to go full screen. However, on some mobile browsers (like Safari on iOS), the address bar may remain visible due to OS restrictions. In that case, try scrolling down to hide the bar or manually zooming in to fill the screen. To exit, tap the screen to reveal the controls, then use the close button.
Q. What is a screen uniformity test?
A. A screen uniformity test displays the same white or gray color across the entire screen so you can visually compare brightness and color from the center to the edges and corners.
Q. What is gray uniformity?
A. Gray uniformity describes how evenly a display shows the same shade of gray across the screen. Uneven dark patches, tint changes, or shadowy areas may become easier to see on gray test screens.
Q. What is the Dirty Screen Effect?
A. Dirty Screen Effect (DSE) is a blotchy or shadowy appearance that can become visible on uniform gray or light-colored screens. This tool can help you visually inspect for this kind of non-uniformity.
Q. Can I test backlight bleed?
A. Yes, on LCD displays. Use the black full-screen test in a dim room and look for unusually bright areas around the edges or corners. OLED displays do not use an LCD-style backlight.
Q. Does uneven color mean my display is defective?
A. Not necessarily. Viewing angle, panel characteristics, display settings, and room lighting can all affect what you see. Check the manufacturer’s specifications and warranty terms if the issue concerns you.
Q. Can I use this test on an OLED display?
A. Yes. White and gray screens can help you visually inspect color and brightness uniformity on OLED displays. Backlight bleed, however, is an LCD-specific concern because OLED displays do not use a backlight.