Brightness Test

How to use the brightness test

The test lays a black overlay over a white field. In the "All 10 levels" view, ten bands sit side by side, from no overlay (0%) to a 90% overlay, each labeled with its percentage. In the "One level" view, a single field fills the area at the overlay you choose with the slider, from 0% to 90%.

1. 1

   Open it full screen. The bands keep their labels in fullscreen. The single field shows only the chosen level.

2. 2

   Check that every band looks different. From your usual seat, each band should be a little darker than the one to its left. Look at the screen straight on, because on many panels the bands shift when seen from an angle.

3. 3

   Watch both ends. If the 0% and 10% bands look the same, the display may be losing detail in bright areas. If the 80% and 90% bands merge, it may be losing detail in dark areas, often because brightness is set low or room light is reflecting off the panel.

4. 4

   Compare settings. Change the display's brightness or contrast and look at the bands again.

What the percentages mean

Each percentage is the strength of the black overlay, not a measure of light. The 50% band is gray level 128, which a display shows at well under half the light of white, because screen levels follow a curve rather than a straight line. Use the numbers to tell the bands apart, not to measure brightness.

For a single adjustable gray, use the Gray Screen. To check contrast and dark detail, use the Screen Contrast Test and the Gamma Test.