Colour Gamut
Definition
Colour gamut is the range of colours that a display or a colour standard can reproduce, usually drawn as a triangle on the CIE 1931 chromaticity diagram. Measured as a share of that diagram, Rec.709 (ITU-R BT.709, the HD standard) covers about 35.9%, DCI-P3 (digital cinema) about 53.6% and Rec.2020 (ITU-R BT.2020, for UHD and HDR) about 75.8%. Many LED panels have a native gamut wider than Rec.709, so Rec.709 content shown without colour conversion looks oversaturated on them.
In the field
LED processors and media servers can convert the panels' native gamut to the target colour space, Rec.709 for most broadcast work, through built-in colour settings or a LUT. Without that conversion, skin tones tend to shift towards orange and saturated colours clip on camera.
Sources
- ITU-R BT.709 : primaires et point blanc de la HD · itu.int
- ITU-R BT.2020 : primaires de l'UHD à large gamut · itu.int
- Wikipédia, Rec. 2020, couverture du diagramme CIE 1931 : Rec.2020 75,8 %, DCI-P3 53,6 %, Rec.709 35,9 % (pointeur secondaire) · en.wikipedia.org
- Christie, Understanding Rec. 2020 : comparaison des gamuts Rec.709, DCI-P3 et Rec.2020 · christiedigital.com