What is a dead pixel and how is it different from a stuck pixel?
A dead pixel is a sub-pixel whose transistor has failed — it receives no power and stays permanently black on every colour field. A stuck pixel, by contrast, is locked at one specific colour (usually red, green, or blue) because one of its three sub-pixels is jammed in the on state. Dead pixels are effectively unrecoverable. Stuck pixels can sometimes be revived by rapidly cycling RGB colours, which warms the sub-pixel transistor and unsticks it. Cycle every fullscreen field — red, green, blue, white, black — and any anomaly that stays black on every field is dead; anything that holds one hue is stuck.
How does the dead pixel fixer actually work?
The fixer flashes pure red, green, and blue fullscreen at roughly 30 frames per second. The rapid voltage swings across the stuck sub-pixel transistor can dislodge trapped charge and restore normal switching. It is not magic — success rates are around 30–50% for genuinely stuck pixels, zero for dead ones. Park the fixer over the affected region for 10 minutes minimum, and up to an hour for stubborn cases. Manufacturers like Dell, LG, and ASUS use similar techniques internally during QC.
What counts as an acceptable number of dead pixels under warranty?
ISO 9241-307 defines four pixel-fault classes. Most consumer monitors ship under Class II: up to 2 fully bright sub-pixels, 2 fully dark sub-pixels, and 5 stuck sub-pixels per million pixels are tolerated before warranty replacement applies. A 4K panel has ~8.3M pixels, so a single dead pixel rarely qualifies. Premium and professional displays (Eizo ColorEdge, Apple Pro Display XDR) often promise Class I — zero defects. Check the manufacturer's pixel policy before claiming.
Why do I see a 'dead pixel' that's actually just trapped dust?
Dust trapped between the panel layers or on the backlight diffuser can look identical to a stuck pixel from a normal viewing distance. The tell-tale signs: dust spots are usually larger than a single pixel, irregularly shaped, and visible mainly on white or light backgrounds. View the white field and the black field — a true dead pixel is invisible on black, while dust is faintly visible on both. Internal panel dust requires factory service to remove.
Does this test work on phones, TVs, and laptops?
Yes. The test simply fills the browser viewport with a flat CSS background — no compression, no dithering, no scaling artifacts. Use fullscreen mode (F11 on desktop) for best coverage. On TVs, cast the page via Chromecast or open it in the TV's built-in browser. For OLED panels, the black field will appear truly black because individual pixels switch off — any glowing pixel on a black field is stuck on. Pair this with /monitor/uniformity to check for backlight bleed and IPS glow.
How often should I check for dead pixels?
Run a check at unboxing (within the seller's return window, usually 14–30 days), after any physical shock, and whenever you notice an odd spot. New pixel failures rarely appear in mid-life — most defects are present from manufacture but only become obvious on specific colour fields. After a stuck-pixel fixer run, recheck with all eight solid fields. For deeper panel health, combine this with /monitor/banding, /monitor/uniformity, and /monitor/gamma.