Gamma Test

How the comparison works

Each column has two halves. The top half is a pattern of black and white lines, one device pixel thick, which averages to exactly half the light of white. The bottom half is a solid gray. Gamma describes how a display turns a number into light: with a gamma of 2.2, half the light comes from level 186, not from level 128. Each column's gray is the level that should match the lines at that gamma: 174, 180, 186, 191, and 195.

1. 1

   Open it full screen and set browser zoom to 100%, so the lines stay one pixel thick.

2. 2

   Step back or squint until the lines blur together into a flat tone.

3. 3

   Find the column whose two halves look most alike. Its label is your display's approximate gamma.

4. 4

   Look straight on. Gamma changes with viewing angle, especially on VA and TN panels.

What the result means

Most content for computers and the web is made for a gamma of about 2.2, so a match near 2.2 means images and photos should look as intended. A lower value makes dark areas look washed out; a higher value makes them look heavier and can hide shadow detail. Many displays have a gamma setting in their menu, and operating systems can adjust it as well.

For shadow and highlight steps, use the Screen Contrast Test; for smooth ramps, the Color Banding / Gradient Test. How to Calibrate a Monitor puts the gamma check in order with the other adjustments by eye.

If no column matches

If every column looks wrong, the lines are probably not landing on single pixels: check that browser zoom is 100%, that the display runs at its native resolution, and that you are not viewing this through screen sharing or a recording. Very low brightness and strong viewing angles also shift the match. Try again straight on, at a normal brightness.