> Recommendation ITU-R BT.2100 – Image parameter values for high dynamic range television for use in production and international programme exchange, specifies parameters for High Dynamic Range television (HDR-TV) signals to be used for programme production and international programme exchange. This Report provides background information on HDR in general, and for the perceptual quantization (PQ) and hybrid log-gamma (HLG) HDR signal parameters specified in the Recommendation.
For instance, it confirms what I said elsewhere that 8-bit is mostly fine for consumers to watch HDR:
> The non-linearity employed in legacy television systems (Recommendations ITU-R BT.601, BT.709 and BT.2020) is satisfactory in that 10-bit values are usable in production and 8-bit values are usable for delivery to consumers; this is for pictures with approximately 1 000:1 dynamic range[5], i.e. 0.1 to 100 cd/m2.
> [Footnote 5]: This definition of dynamic range refers to the luminance ratio between the dimmest and brightest possible pixels presented on the display. However quantization artefacts, known as banding, may be visible, particularly in low lights, at luminance levels substantially brighter than the dimmest pixel. Quantization artefacts may, therefore, limit the “effective” dynamic range that is free from banding.
> The PQ HDR system generates content that is optimum for viewing on a reference monitor in a reference viewing environment. The reference monitor would ideally be capable of accurately rendering black levels down to or below 0.005 cd/m2, and highlights up to 10 000 cd/m2. Also, the ideal monitor would be capable of showing the entire colour gamut within the BT.2020 triangle. The viewing environment would ideally be dimly lit, with the area surrounding the monitor being a neutral grey (6 500 degree Kelvin) at a brightness of 5 cd/m2. However, content often must be viewed or produced in environments brighter than the reference condition, and on monitors that cannot display the deepest blacks or brightest highlights that the PQ signal can convey. In these cases the display characteristic needs to be changed in a process often referred to as display mapping (DM).
Some of the most interesting sections of BT.2390 are on the advantages of ICTCP or ITP, for short, which is used by Dolby Vision. Apparently due to “constant intensity” if I’m reading this correctly, YCbCr is less preferred and if possible, RGB (in full 4:4:4) is preferred, or one of the other encodings suggested, like ITP or "Y′CC′BCC′RC". https://professional.dolby.com/siteassets/pdfs/ictcp_dolbywh... might also be relevant here.
Note that BT2020 describes a wider color gamut, not an extended dynamic range. BT2100 is the HDR equivalent.