How to Test a New TV for Dead Pixels and Uniformity

TVs are big, so defects are easy to miss — and easy to spot once you know what to display.

Do this in the first week. A retailer's return policy is almost always more forgiving than a manufacturer's pixel policy, so the cheapest moment to reject a bad panel is before the return window closes. Check what that window actually is on your receipt before you start.

Set the TV up honestly first

Three things will lie to you if you skip them.

• Picture mode. Switch to Filmmaker, Movie, or Cinema. Showroom modes like Vivid and Dynamic crush shadow detail and oversaturate everything, which hides some faults and invents others.
• Auto-dimming. Turn off the ambient light sensor, eco mode, and any energy-saving brightness limiter. Otherwise the screen changes under you mid-test and you will chase a fault that is really just the sensor working.
• The room. Kill the lights. Backlight and black-level problems are close to invisible with a lamp on, and uniformity problems disappear entirely in daylight.

Let the set run 20–30 minutes before judging uniformity. Panels shift slightly as they warm up.

Get a test pattern on screen

• Smart TV: open the built-in web browser and load this site.
• No browser: cast or mirror from a phone, or use a USB stick with solid-color images.
• Anything else in the room: a game console browser, a laptop over HDMI, or a streaming stick all work.

What matters is a genuinely full-screen field with no menu bar, no overlay, and no player controls fading in over the top.

The tests

1. Pixels — full-screen red, green, blue, white, and black via the Color Test. Get within arm's reach and sweep the panel in overlapping strips; a 65-inch screen is far too big to judge in one glance. A dead pixel stays black on every field. A stuck pixel stays lit in one color and jumps out on the opposite field, so a stuck red dot is easiest to find on green or blue. The Dead Pixel Test cycles the fields for you, and Dead vs Stuck vs Hot Pixels covers telling them apart.
2. Dirty screen effect (DSE) — a 5% gray or Brightness Uniformity field shows vertical bands and blotches that ruin panning shots in sports. This is the most useful TV test and the one almost nobody runs. Look for vertical stripes, a darker middle, and cloudy smudges. Check a mid-gray field too: some sets look filthy at 5% and clean at 50%, others the reverse.
3. Backlight and blooming — on LED and Mini-LED sets, the Blooming Test reveals halos around bright objects on black. Every backlit panel does this to some degree; the question is how big the halo is and whether it visibly lags behind the object as it moves. A halo that trails the object is the local dimming algorithm reacting late, and it will show up on white subtitles over a dark scene.
4. OLED black — on OLED, a Black Screen should look truly off, with no glow. Faint vertical banding on a very dark gray is a common OLED trait rather than a fault; judge it on real content before you call it a defect.
5. Burn-in and image retention — mandatory on anything used, refurbished, or ex-display. Run the Burn-in Test and look for a ghosted news ticker, channel logo, or menu bar in the gray fields. OLED Burn-In: Causes, Prevention, and How to Check explains what is temporary retention and what is permanent.

Normal versus worth returning

| What you see | Usually normal | Push for a return when | | --- | --- | --- | | Faint corner glow on an LCD in a dark room | Yes, especially on IPS | It is visible during normal viewing, not just on a black test field | | Light vertical banding on a 5% gray field | Common on large VA and OLED panels | You can see it in a panning shot of a football pitch | | Halo around bright objects on black | Yes on any backlit LED set | The halo is larger than the object, or clearly lags it | | One dim or stuck subpixel | Often within the maker's policy | It is near the center, or there is more than one | | A dark patch that does not move with content | No | Always — see Why Does My Screen Have a Dark Spot or Patch? |

Viewing distance matters

Step back to your normal seating distance before judging. A single pixel invisible from the couch isn't worth a return; a gray-uniformity band visible across the room is. Sit down, look at the same pattern again, and only count what you can still see from the sofa.

One caveat: once you know a flaw is there, you will see it forever. If you are genuinely unsure, live with the set for a few days on normal content. If it never bothers you again, keep it.

If you do need to claim

Photograph the fault in a dark room with the phone's exposure and focus locked, and include a shot with something in frame for scale. Note the date, the pattern you used, and where on the panel it sits. Retailer returns rarely require any of that, but manufacturer pixel policies usually demand a minimum number of failed pixels before a panel qualifies — Dead Pixel Warranty Policies, Explained covers how those thresholds work and which faults sidestep them entirely.