Screen Uniformity Test

What is this tool?

Screen uniformity is whether the same colour looks the same everywhere on the panel. Two things can go wrong: brightness uniformity, where one area is lighter or darker than another, and colour uniformity, where one area carries a tint the rest does not.

The engine organises the inspection into five categories — brightness, grayscale, colour, dark level and custom colour — and drives a thirteen-step automated sequence with a dwell timer, so each field is on screen long enough to judge before it moves on.

Observations are mapped to a nine-zone grid: the four corners, the four edge midpoints and the centre. Recording which zone differs is what makes the result comparable between panels and between inspections.

How to use it

1. Set the room and the viewing angleRoom options are Dark, Dim, Normal and Bright; angle options are Center, Left, Right, Above and Below. Set them to what is true — both change the result substantially, and a recorded observation is only meaningful alongside the conditions it was made in.
2. Choose a modeSTANDARD, PRECISION, DARK ROOM, COLOR and FULL PANEL. Start with STANDARD for a general look. DARK ROOM is for the dark-level fields, where clouding is visible. COLOR is for tint hunting.
3. Let the sequence run, or step through itThe automated sequence has thirteen steps and holds each one for a dwell period with a live countdown — five seconds by default. Wait out the dwell rather than clicking through; uniformity faults become visible after a couple of seconds, not instantly.
4. Compare zones deliberately, not globallyLook at each corner against the centre, then each edge midpoint against the centre. Your eye adapts to a gradient and will call an uneven screen even if you take it in as a whole, so compare pairs of zones instead.
5. Grade each observationZone and edge severities are Uniform, Slight variation, Moderate variation and Strong variation. Clouding runs None visible, Very slight, Slight, Moderate, Strong. The overall assessment reads Excellent, Good, Fair, Poor or Severely Uneven — all of it built from the grades you enter.
6. Repeat on white, grey and blackThe page has separate sections for each, because each reveals different faults. White shows tint and vignetting, mid grey shows brightness variation most clearly, and black shows clouding and leakage.

What the results mean

Brightness patches

An area consistently lighter or darker than its neighbours across grey fields. Mild variation is normal on every LCD; a patch you can see without hunting for it is worth recording with its zone.

Vignetting and glow

A gradual fall-off from centre to corners, or the reverse. Because it is gradual rather than a hard edge, it is easiest to catch by comparing one corner directly against the centre.

Colour consistency

One region carrying a tint — typically warm on one side and cool on the other — on a field that should be neutral. Most visible on white and mid grey, and the reason the COLOR mode exists.

DSE (distinct shading effect)

Visible banding or blotching in dark and mid-grey fields, named on the page as its own outcome. It is a backlight and diffuser characteristic rather than a pixel fault, and it shows up most in dark, slow-moving content.

The overall assessment

Excellent, Good, Fair, Poor or Severely Uneven, derived from the zone and edge grades you entered plus the clouding grade. It summarises your inspection — it is not an independent measurement of the panel.

What it can detect

• Brightness variation between the nine mapped zones
• Centre-to-edge fall-off and vignetting
• Colour tint that differs across regions of the same field
• Clouding and distinct shading effect on dark and grey fields
• Whether an apparent problem is really a viewing-angle effect — by repeating the inspection from five angles

Limits worth knowing

A browser can only report what the platform gives it. These are the honest boundaries of this page, so a result is never read as more than it is.

• The page has a “Browser Test Limitations” section and its FAQ asks “Can a browser automatically measure screen uniformity?”, “Can this test measure brightness in nits?” and “Can this test measure Delta E?” No to all three. No nit value and no Delta E figure is produced anywhere in this tool.
• Professional uniformity measurement uses a colorimeter or spectrophotometer placed against the panel at a grid of points — the page explains the method in its own section. That equipment measures light; a web page can only display it.
• The severities and the overall assessment are your grades, structured and recorded. They are repeatable because the fields and zones are fixed, not because anything was measured.
• Viewing angle contaminates uniformity judgement on every panel, especially IPS. A corner you are looking at obliquely will genuinely look different, which is why the angle control exists and why the record should note it.
• Some variation is normal, and the page says so. Manufacturers publish their own uniformity tolerances; judging a panel means comparing against those.

Tips

• Photograph each field at a fixed exposure if you want a record. Auto exposure defeats the comparison by re-metering every shot.
• Sit at your normal distance. Uniformity faults that only appear from 20 cm away rarely matter in use.
• Do the dark-level fields last, after your eyes have adapted. They are the most revealing and the most sensitive to adaptation.

Troubleshooting

Related documentation

• DisplayBacklight Bleeding TestA pure black screen and a structured five-angle inspection for light leakage.
• DisplayDead Pixel TestFull-screen solid colours for finding dead, stuck and hot pixels by eye.
• DisplayScreen Flicker TestSteady and alternating fields for spotting flicker, at brightness levels you choose.
• DisplayDisplay Response Time TestControlled colour transitions for judging pixel response, trailing and overshoot by eye.
• DisplayRefresh Rate TestEstimate your display's refresh rate from frame timing, with a confidence level attached.