The signed distance from a source's chromaticity to the Planckian locus on the CIE 1960 u, v diagram. Positive values sit above the locus and look greenish; negative values sit below it and look pinkish or magenta. Tolerances for nominal CCT bins allow about plus or minus 0.006, and many people prefer whites slightly below the line. Two lamps with identical CCT can look obviously different if their Duv differs.
Same 3000 K on paper, but this one's Duv is plus 0.005 and it looks green next to the incandescent.
When a client says the light looks green or looks pink, they are describing Duv, not CCT.
Also heard as
- delta uv
- tint
Related terms
CCT
Correlated Color Temperature: the warm-to-cool appearance of white light, stated in kelvin.
Planckian locus
The line of whites on a chromaticity diagram that a perfect blackbody passes through as it heats up.
Chromaticity
Where a light's color sits on a color map once brightness is set aside, given as coordinates such as x, y or u', v'.
Minus green
A magenta correction gel that removes the green tint from fluorescent or green-shifted LED light for camera work.