What is a Dead Pixel Test?
A dead pixel test fills your entire screen with a single solid color, making it easy to spot any pixel that is not displaying correctly. By cycling through red, green, blue, white, black, cyan, magenta, and yellow, you can isolate faulty subpixels and determine whether your display has a defect.
Modern LCD, OLED, and LED screens contain millions of tiny pixels, each made up of red, green, and blue subpixels. When one or more subpixels malfunction, the result is either a dead pixel (always dark) or a stuck pixel (permanently showing one color).
Dead Pixels vs. Stuck Pixels
- **Dead pixel**: A pixel that receives no power and appears as a tiny black dot on every background color. Dead pixels are usually permanent and cannot be repaired through software. - **Stuck pixel**: A pixel where one or more subpixels are locked in an on state, displaying a constant red, green, blue, or mixed color regardless of the image. Stuck pixels can sometimes be fixed by gently massaging the area or running rapid color-cycling software.
How to Use This Tool
1. Select a test color from the palette or leave the default. 2. Click **Start Full-Screen Test** to fill your display with the selected color. 3. Carefully scan the entire screen for any dots that differ from the surrounding color. 4. Click anywhere on the screen or press the right arrow key to advance to the next test color. 5. Press **Escape** to exit the test at any time.
For best results, perform the test in a dimly lit room and clean your screen beforehand so dust particles are not confused with pixel defects.
Why Each Color Matters
- **Red, Green, Blue**: Each isolates one subpixel channel. A stuck subpixel will be invisible on its own color but clearly visible on the other two. - **White**: Turns all subpixels on. Dead pixels are most visible against a white background. - **Black**: Turns all subpixels off. Stuck pixels that glow faintly are easiest to spot on a black screen. - **Cyan, Magenta, Yellow**: These secondary colors test pairs of subpixels together, catching defects that may only show when two channels combine.
Who Should Use This Tool
- **New device buyers**: Check a new monitor, laptop, tablet, or phone for manufacturing defects before your return window closes. - **Used device shoppers**: Verify the screen condition of a secondhand display before purchasing. - **Gamers and designers**: Ensure your display is defect-free for color-critical work or immersive gaming. - **IT professionals**: Quickly audit multiple displays during deployment or troubleshooting.
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