Screen Color and Uniformity Test

How to run the uniformity test

1. Let the screen warm up for a few minutes, set it to its normal brightness and turn off any “dynamic contrast” or eco mode, which can change the image while you test.
2. For the dark patterns, dim the room. Sit straight in front of the screen at your usual distance.
3. Press Start full-screen test, or click a swatch under Grey levels, Colours, Gradients or Steps and levels to jump straight to that pattern.
4. Click or tap to go to the next pattern; click the left third of the screen (or right-click) to go back. Arrow keys, Space and Page Up/Down work too, and H shows the help again.
5. Tick Show a 3 × 3 grid to compare zones if you want to compare the corners, edges and centre one by one.
6. Press Esc or ✕ Exit to leave. The pointer and the labels fade out so they don’t get in the way.

What each pattern reveals

Black (0 %) shows backlight bleed on LCD screens: bright patches that leak from the edges or corners. On IPS panels you may also see “IPS glow”, a silvery or warm sheen in the corners that changes when you move your head. Bleed stays put; glow moves with your viewing angle.

Grey 5 % and Grey 10 % are the most revealing patterns for clouding (blotchy, uneven dark areas) and for “dirty screen effect” on large TVs and VA panels. On OLED, very dark greys expose near-black flicker, vertical banding and uneven gamma.

Grey 25 %, Grey 50 % and Grey 75 % show vignetting (darker corners), brightness falloff from the centre and colour tint shifts, where one area looks slightly pink or green compared with another. OLED burn-in often shows up best on mid greys.

White (100 %) and the pure Red, Green and Blue screens reveal uneven colour and brightness, and are also useful for spotting dead or stuck pixels.

The Black to white, horizontal and vertical gradients should look perfectly smooth. Visible bands mean the panel, the cable or a colour profile is reducing the bit depth. The coloured gradients check each channel separately.

32 grey steps should show 32 distinct, evenly spaced bands. Near-black steps (0–20) shows eleven bands from level 0 to 20 in steps of two: on a well-adjusted screen you can tell at least most of them apart. If the left bands merge into one black, shadow detail is being crushed; adjust brightness or black level. Near-white steps (235–255) does the same for highlights.

How to judge the results

No screen is perfectly uniform. Differences of a few percent in brightness across a panel are normal, and most eyes won’t notice them in real content. Judge the dark patterns at a normal brightness, not at maximum, and don’t photograph them with a phone: the camera exaggerates bleed and glow dramatically. If you are within a return period and the issue is visible in films or dark games, that is the time to act.

The grey levels in this tool are sRGB code values (5 % is level 13 of 255), not measured luminance. For precise measurements you need a colorimeter.