Screen Test Online: Uniformity, Banding, Sharpness and Gamma

How to use it

Choose the Pattern to start with and press Start full-screen patterns.
Look at each pattern from a normal distance, then click or press the right arrow or Space for the next.
Use the arrow keys to go back, and press Esc to close the test.
Read the section that explains each pattern to see what it shows.

Uniformity: solid greys

A solid grey has no content, so any patch that is brighter, darker or tinted stands out. Look for a bright corner, a dark edge or a band that is not even. On backlit panels the edges and corners often look slightly different; a faint difference is normal, but a strong one points to uneven lighting.

Gradient banding

A smooth gradient should change gently from one side to the other. Visible steps, called banding, appear when a screen can show only a limited number of levels. Many panels use dithering to hide the steps, so faint steps are normal; strong vertical bars point to a limit of the panel or of its colour depth.

Sharpness and text clarity

The fine lines alternate black and white on every second screen pixel. If they blur into grey, the scaling or the panel is softening the image. The text samples in several sizes show how clearly small letters are drawn, including the Turkish letters ı, İ, ğ, ş, ç, ö and ü.

Near-black steps and gamma

The 16 squares show grey levels 0 to 15 out of 255, from black to very dark grey. On a good screen you can tell most of the steps apart; if the first several look the same, shadow detail is lost. The gamma check places a fine black and white checker next to a solid grey of the same average brightness, sRGB 188. At a normal distance, a screen that follows the standard gamma shows the two as one even tone. If one side looks clearly brighter or darker, the gamma or brightness setting may be off. It is a visual check, not a calibrated measurement.

Viewing angle

Look at the bands from the side, about 45 degrees to the left, to the right, above and below. The colours should keep their brightness. A panel with a narrow viewing angle turns the dark bands grey or shifts their colour when you look at it from the side, and the test shows how much.

Example: reading the near-black steps

The squares show grey levels 0 to 15 out of 255. Level 0 is pure black. Level 15 is #0f0f0f, a value of 15 on the 255 scale, about 6 % of the way from black to white in code values. If the first few squares look identical, the screen is hiding shadow detail below that level.

Frequently asked questions

Does the test record anything?

No. The patterns are drawn in your browser on the screen you are looking at. Nothing is recorded, stored or sent to our server.

Why do the corners look brighter or darker?

Backlight and panel differences can make edges and corners look different. A little unevenness is normal on LCD screens. Check at full brightness on a plain white or grey pattern, and read your warranty before you contact the maker if the problem is strong.

Why is banding visible on a smooth gradient?

Some panels show a limited number of levels per colour or do not dither, so the steps of a gradient become visible. Changing the colour profile, the brightness or the picture mode can change how visible they are.

What is the gamma check for?

It shows whether the brightness of the picture rises the way the standard expects. Most screens are close to the standard; a large difference suggests that a setting such as a picture mode or a colour profile is off. It is not a calibration.

Does the test work on a phone?

Yes. Use the same steps on a phone or tablet. Full screen hides the browser bars on most phones; otherwise the patterns fill the browser window.

Sources

Figures and text last checked on Tuesday, November 10, 2026.