How to spot each defect type
- White screen: dead pixels appear as sharp black dots.
- Black screen: stuck subpixels glow as pinpoint red, green, blue, or white dots.
- Red, green, blue screens: a dot on one primary color but not the others isolates the faulty subpixel.
- Gray screen: good for subtle defects and doubling as a quick uniformity check for backlight clouding.
Found a defect? What to do next
- Note the color behavior: black on white = dead; colored on black = stuck.
- Photograph it on the color where it is most visible, with the whole screen in frame.
- For stuck pixels, try a flashing-color exerciser over the area for a few hours and re-test; some recover.
- Check your manufacturer's pixel policy and warranty window — bright (stuck) defects are often covered at lower counts than dark ones.
- Re-run this test after any repair or replacement panel arrives.
Want a fuller display inspection — gradients for banding, a 1px checkerboard for scaling, and text sharpness? Run the complete monitor test. On a touch device, pair it with the touch screen test to check the digitizer as well as the panel.
Dead pixel questions
Start the test to go fullscreen, then inspect the screen carefully on each solid color, advancing with a click or the arrow keys. Dead pixels show as black dots on the white screen; stuck subpixels show as tiny red, green, or blue dots on black and on the opposite primary colors. Clean the screen first — dust is the great impostor.
A dead pixel receives no power and stays black on every color — most visible on white. A stuck pixel has one or more subpixels frozen on, so it glows red, green, blue, or a mix, and is most visible on black. Stuck pixels sometimes recover; dead pixels almost never do.
Sometimes. Leaving the display on rapidly changing colors over the stuck area for some hours revives a share of stuck subpixels, and some recover on their own over days. Gentle massage techniques are widely described online but risk damaging the panel — attempt them at your own risk, never with hard pressure on an LCD or any pressure on OLED.
It depends on the manufacturer’s pixel policy, many of which follow ISO 9241-307 classes: Class I panels allow zero defects, while common Class II policies tolerate a small number of bright or dark subpixel defects before replacement. Check your vendor’s policy, count and photograph the defects on the relevant test colors, and cite both in a claim.
That is the signature of a single stuck or dead subpixel. Each pixel has red, green, and blue subpixels: a dead red subpixel disappears on pure blue or green screens but shows on red and white. Cycling all primary colors is what isolates which subpixel is faulty.