How to check a laptop screen for dead pixels and backlight bleed
A laptop screen check runs entirely in your browser: click one of six solid color fields (red, green, blue, black, white, yellow) and the display fills edge to edge so defects stand out. Nothing is uploaded and no account is needed. Watch for pixels stuck the wrong color, dust, or darker patches near the bezel.
Last reviewed: 2026-07-01
| Property | Value |
|---|---|
| Format | Online, no install, no sign-up |
| Cost | Free |
| Implementing tool | https://freetoolonline.com/device-test-tools/lcd-test.html |
Test one color at a time so each defect class surfaces against the field that exposes it. A black field reveals stuck-bright pixels that never switch off; a white field reveals dead-dark pixels and surface dust; the red, green, and blue fields each isolate subpixel faults in that channel; and yellow stresses red and green subpixels together. The black field also separates real backlight bleed from a viewing-angle gradient. Genuine bleed reads as a warm-grey wash fading inward from the bezel and stays put when the panel is square to your eye, while a viewing-angle cast shifts or disappears as you tilt the lid. A corner that still reads cooler when you look straight on is worth a warranty conversation.