 For a CRT, the gamma that relates brightness to voltage is usually in the range 2.35 to 2.55; video look-up tables in computers usually adjust the system gamma to the range 1.8 to 2.2, which is in the region that makes a uniform encoding difference give approximately uniform perceptual brightness difference, as illustrated in the diagram at the top of this section.For simplicity, consider the example of a monochrome CRT.In this case, when a video signal of 0.5 (representing a mid-gray) is fed to the display, the intensity or brightness is about 0.22 (resulting in a mid-gray, about 22% the intensity of white).