The Full Width at Half Maximum (FWHM) is a method for evaluating analog functions such as filter curves. For a distribution function such as the Gaussiandistribution curve, there are two extremes: the minimum value and the maximum value. In between, at 50%, is the FWHM value, which corresponds level-wise to half the maximum level.
The FWHM value is also applied to distribution functions, for example in lighting technology, color pixels, LED lights, light distribution or energy distribution, pulse width, optical fibers, signal processing, level specifications, and the aperture angle of radiation lobes of antennas. In terms of power, the FWHM value corresponds to the -3- dB value. If the distribution function has a time basis, then Full Duration at Half Maximum (FDHM) is often used instead of FWHM.
The FWHM value plays a decisive role for color pixels. The narrower the spectral width of a color pixel, the larger the color space. The difference can be seen between OLEDs and quantum LEDs( QLED). The former have a spectral width of 40 nm, whereas QLEDs have one of 20 nm.