Instead, the brightness produced by a CRT is proportional to the input voltage raised to a power. This power is a variable called gamma. The value of gamma varies depending on the CRT, but is usually between 1.4 and 3.0. Since most sensors used in television cameras produce output voltages proportional to scene brightnesses, a correction for CRT gamma must be applied to the camera signal to avoid having midtones in the scenes being too dark on the TV set. With a single TV camera feeding millions of TV receivers it made economic sense to compensate for CRT gamma in the studio's equipment.
Most computer displays ignore the effect of monitor gamma.
The frame buffer values provided by the application software are converted linearly into voltages that drive the CRT in the display. But because of the effect of monitor gamma, the values in the frame buffer are not linearly proportional to the resulting brightness. Some display systems such as NeXT's Dimension board do contain circuitry that correct for monitor gamma. On a NeXT Dimension system the frame buffer values provided by the application are corrected for the gamma value of the CRT, producing a display system gamma of 1.0 which linearly maps frame buffer values into brightness. Also, a 1-bit display that produces gray scales by dithering between two values will have a linear brightness response no matter what the monitor's gamma response is.