Screen test

A dead pixel receives no power and stays black on every colour, including a full white field. A stuck pixel is permanently lit in one colour, so it shows as a bright red, green, blue or white dot against black.

The distinction matters because stuck pixels sometimes recover on their own or with a flashing pattern, while dead pixels effectively never do.

Sometimes. The flashing pattern rapidly cycles colours to exercise a sub-pixel that has got lodged, and it does occasionally free one. Leave it running over the affected area for ten to thirty minutes.

It is not guaranteed and it does nothing for a genuinely dead pixel. If the flashing is uncomfortable to watch, look away, and skip it entirely if you are sensitive to flashing light.

More than most people expect. Manufacturers work to published defect policies, and many will not consider a panel faulty until several dead sub-pixels are present, or one is in the central zone.

Test a new monitor or laptop as soon as it arrives and photograph anything you find, because return windows are short and the evidence is easier to gather on day one.

Backlight bleed is light escaping around the edges of an LCD, visible as brighter patches on a black field in a dark room. It is a byproduct of how LCDs are built and essentially every LCD has some.

Judge it in normal viewing rather than face-on in a blacked-out room, where every panel looks bad. If you notice it during ordinary use, it is excessive; if you can only find it while hunting for it, it is normal.

IPS glow is a silvery haze in the corners that shifts as you move your head, and it is inherent to the IPS panel type rather than a defect. Backlight bleed stays put when you move.

That movement test is the quickest way to tell them apart, and it matters because glow is not covered by any warranty while severe bleed sometimes is.

Visible steps instead of a smooth fade usually mean the panel or the pipeline is working at a lower colour depth than the image needs. Many panels are 8-bit or 6-bit with dithering.

Before assuming the panel, check the colour depth setting in your graphics control panel, and check the cable: an under-specified HDMI or DisplayPort cable at high resolution and refresh rate will reduce depth to keep up.

It measures how often the browser can actually paint, which normally matches your display's refresh rate closely. It is a good check of whether a high refresh monitor is genuinely running at its rated speed.

Variable refresh rate, battery saving modes and a busy machine can all pull the reading below the panel's maximum, so take a reading with the system otherwise idle.

Yes, and the solid colour fields are the right tool. Burn-in appears as a faint permanent ghost of something previously shown, usually a taskbar, a logo or a heads-up display, and it is most visible on a mid-grey or a solid colour field.

Uniform full-screen colour also drives most OLED panels' own pixel refresh routines, which is a reasonable maintenance habit for a screen that shows static content.

Yes. Full-screen mode works on most mobile browsers, though iOS Safari restricts it in places, in which case scroll the page so the colour field fills the display.

On a TV, open the page in the built-in browser or cast a laptop to it. Turn off any motion smoothing and dynamic contrast processing first, because both alter what you are trying to measure.

Ambient light washes out exactly the faults you are looking for. Backlight bleed, clouding, black uniformity and faint stuck pixels are all low-contrast details that room light hides completely.

Bright fields are the exception: check white and light grey in normal lighting, since that is where dead pixels and dust show best.