How the test works

Dim the room first – backlight bleed and glow are easiest to see in the dark. Sit straight in front of the centre of the screen at your usual distance. Seen at an angle, the corners of IPS screens glow more (IPS glow), which can look like a fault.

An optional question, What kind of screen is it?, tailors the advice – OLED, Mini-LED, LCD (IPS, VA) or I don’t know.

The whole screen then shows black, dark grey, grey, mid grey and white, one at a time. Tap or click for the next colour – nothing flashes. At the end you pick everything you noticed, and the result says whether the screen looks even and what to do next.

What to look for on each colour

• Black – light glowing from the edges or corners. On LCD screens this is usually backlight bleed (light leaking past the edges of the panel) or IPS glow (a soft corner glow that changes with your viewing angle).
• Dark grey – cloudy patches, a slight tint, or edges darker than the centre (vignetting).
• Grey and mid grey – blotchy bands, known as the dirty screen effect (DSE). In films and sport it looks like a dirty window when the camera pans across a sky or a pitch.
• White – darker or tinted areas, such as a pinkish or greenish side.

LCD: backlight bleed or IPS glow?

An LCD lights the picture from behind with a backlight, so some edge glow on black is common – and on IPS screens, so is IPS glow. Mini-LED screens are LCDs too, with a backlight made of many small LEDs.

To tell the two apart, move your head slowly. IPS glow changes or fades. Backlight bleed stays in the same place.

Lowering the brightness a little and keeping some light in the room makes both less visible. If the glow is strong in normal use – not only on black in the dark – contact the seller within the return period.

OLED: glow, vignetting and tint

OLED screens have no backlight – each pixel makes its own light and switches off for black. A glow on black usually comes from room light reflecting on the screen, or from a signal range mismatch (the computer and the screen disagree on which level is black), which can turn black into dark grey. The black level test checks this.

Slight vignetting or a faint tint on dark grey is common on OLED. An occasional panel refresh from the monitor’s menu can help. Strong patches are a warranty case – policies differ, so check the manufacturer’s or seller’s terms. Faint shapes of a taskbar or icons can point to burn-in – see the burn-in test.

More single tests

• HDR brightnessHow bright highlights get, and how much big bright areas dim.
• Black levelTrue black and the darkest shadow detail.
• GradientsStripes in smooth colour ramps – 8-bit or 10-bit.
• ColoursStandard sRGB, Display-P3 or beyond.
• Refresh rateYour Hz right away, plus motion clarity.
• Dead pixelsDark or stuck dots on full-screen colours.
• Burn-inFaint shapes left by static images on OLED.