Rec. 2020

Rec. 2020 is shorthand for Recommendation ITU-R BT.2020, Parameter values for ultra-high definition television systems for production and international programme exchange. CSS Color 4 gives its primaries as red at x 0.708, y 0.292, green at 0.170, 0.797 and blue at 0.131, 0.046, with a D65 white point, and notes that it is used for UHD, 4K and 8K television and can represent almost all visible real-world colours.

The primaries lie very close to the edge of what is visible, which CSS Color 4 says makes them physically realisable only with difficulty, and current displays cannot reproduce the full gamut. In practice Rec. 2020 is a container: HDR video is mastered and delivered in it, while the colours actually used stay within what mastering displays can show. A screen's Rec. 2020 coverage figure is therefore short of full.

A browser reports rec2020 from the color-gamut media query when the system gives it approximately that gamut or more, which few setups do, and CSS can name Rec. 2020 colours with color(rec2020 ...). The colour gamut test reads both and draws a Rec. 2020 colour beside the most saturated sRGB one. Wide gamut and HDR are separate: the HDR test reads whether HDR is on.