Example
Select a solid color and inspect the screen for pixels that do not match. Use grayscale and gradients to look for uneven transitions.
How it works
The browser displays simple CSS patterns locally. Fullscreen is optional and starts only after you press the button; Escape exits it. The slow cycle advances every five seconds and pauses when this tab is hidden.
Frequently asked questions
Can this page find every dead pixel automatically?
No. You inspect the display yourself; the browser cannot reliably identify a physical panel defect.
Will it fix or certify my monitor?
No. It only displays test patterns. It cannot repair hardware or provide a certified diagnostic.
Does it flash quickly?
No. Manual changes happen only when you choose them. The optional cycle changes at a slow five-second interval and can be stopped at any time.
Limits and accuracy
Use realistic values. The tool explains assumptions and does not replace professional, official or safety advice where that applies.