Short answer
Rec. 709 (ITU-R BT.709) is the colour standard for HD television and Rec. 2020 (ITU-R BT.2020) the one for UHD. Rec. 709 has the same primaries as sRGB; Rec. 2020's primaries sit almost on the edge of visible colour. Video differs from web colour in three ways: it encodes camera light (scene-referred) rather than a finished display image, it stores colour as luma plus two colour-difference signals, and it traditionally uses 'narrow range' code values rather than the full 0–255.
BT.709 defines HDTV: the primaries (identical to sRGB's), D65 white, and an opto-electronic transfer function (OETF) describing how a camera should encode light — a linear segment of slope 4.5 near black, then a 0.45 power with offset. Its current edition, BT.709-6, dates from 2015. BT.2020, first approved in 2012 and at edition 2 since 2015, defines ultra-high-definition television: 4K and 8K resolutions, 10- or 12-bit coding, and much more saturated primaries — red at x 0.708, y 0.292, green at 0.170, 0.797 and blue at 0.131, 0.046 — which are monochromatic-like colours near the spectral locus. HDR, which changes the tone curve rather than the primaries, came later in BT.2100.
A common confusion is that video 'is gamma 2.2' or 'is 709 gamma'. BT.709's formula describes the camera; it was never meant to be inverted exactly on the display. The display response for HD mastering is defined separately in BT.1886 (2011) as essentially a 2.4 power. The mismatch between a camera curve that behaves roughly like a 0.5 power and a 2.4 display curve is intentional: it adds end-to-end contrast that compensates for the dim surroundings in which television is typically watched. Transcoding video as if the 709 OETF were the display curve — a frequent error in software pipelines — makes pictures look lifted and flat.
Video is rarely stored as RGB. Encoders convert to Y′ (a weighted sum of the gamma-encoded R′, G′ and B′) plus two colour-difference channels, Cb and Cr, which allows the colour channels to be stored at lower resolution. The weights differ between standards — BT.601, BT.709 and BT.2020 each have their own matrix — so decoding with the wrong matrix tints the picture, typically making greens and reds slightly off. Broadcast video also traditionally uses 'narrow' or 'limited' range, where black is code 16 and white is 235 in 8-bit, leaving headroom and footroom. A player that mistakes narrow range for full range shows grey blacks and dull whites; the reverse crushes shadows and clips highlights.
No mainstream consumer display reproduces all of Rec. 2020: its primaries are so saturated that only laser-based systems get close. In practice UHD and HDR content is mastered within something close to P3 and carried inside a Rec. 2020 container, so the numbers leave room for future displays. That is why 'Rec. 2020 coverage' figures for televisions are typically well below 100% even for premium sets, and why a colour graded to the edge of P3 still sits comfortably inside the signal. For web work, CSS supports color(rec2020 …) and a rec2020 media query, but designing to Rec. 2020 colours today means designing for almost nobody.
| Parameter | BT.709 (HD) | BT.2020 (UHD) | BT.2100 (HDR) |
|---|---|---|---|
| Current edition | 709-6 (2015) | 2020-2 (2015) | 2100-3 (2025) |
| Primaries | Same as sRGB | Near-spectral red, green, blue | Same as BT.2020 |
| White point | D65 | D65 | D65 |
| Transfer | Camera OETF; display per BT.1886 (≈ 2.4) | Same approach as BT.709 | PQ or HLG |
| Bit depth | 8 or 10 bit | 10 or 12 bit | 10 or 12 bit |
Why: A player or platform interpreted narrow-range (16–235) video as full range, or applied the wrong tone curve.
Fix: Check the range and colour tags in the export settings and confirm them with a media-inspection tool.
Why: The decoder used a BT.601 matrix on BT.709 material, or vice versa.
Fix: Make sure the file carries correct colour-primaries, transfer and matrix tags, and that the pipeline preserves them.
Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.
FactStrong evidence
ITU-R BT.709 is currently at edition 6 (06/2015) and BT.2020 at edition 2 (10/2015); BT.2020 was first approved in 08/2012.
StandardStrong evidence
BT.2020 specifies primaries at red x 0.708, y 0.292; green x 0.170, y 0.797; blue x 0.131, y 0.046, with a D65 white point.
Source: ITU-R Recommendations BT.709, BT.2020 and BT.2100; CSS Color Module Level 4
StandardStrong evidence
ITU-R BT.1886 (03/2011) defines the reference display transfer function for HDTV studio flat panels, and CSS Color 4 uses its 2.4 gamma for the rec2020 colour space.
Source: Recommendation ITU-R BT.1886: Reference electro-optical transfer function for flat panel displays used in HDTV studio production; CSS Color Module Level 4
FactStrong evidence
Current displays cannot reproduce the full Rec. 2020 gamut; its primaries lie very close to the spectral locus and are physically realisable only with difficulty.
Source: CSS Color Module Level 4; Liquid crystal display and organic light-emitting diode display: present status and future perspectives
Reviewed 29 September 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.