Mired

Contracted from the term micro reciprocal degree, the mired (/ˈmaɪrɛd/[1]) is a unit of measurement used to express color temperature.

In photography, mireds are used to indicate the color temperature shift provided by a filter or gel for a given film and light source.

For instance, to use daylight film (5700 K) to take a photograph under a tungsten light source (3200 K) without introducing a color cast, one would need a corrective filter or gel providing a mired shift This corresponds to a color temperature blue (CTB) filter.

A number of mathematical methods, including Robertson's, calculate the correlated color temperature of a light source from its chromaticity values.

[8] Apple's HomeKit uses the mired unit for specifying color temperature.