From TLS,Inc. tools - Filter Fax :
CTO color correction filters have a positive mired shift; CTB s have a negative shift.
1,000,000/Daylight 5600K = 179 mireds.Mired is an acronym for micro reciprocal degrees. A light source having a true Kelvin color temperature also has a mired value, computed as follows:
1,000,000/Source in °K. For example: 1,000,000/Tungsten 3200°K=313 mireds.
CTO color correction filters have a positive mired shift; CTB s have a negative shift.