Are you really Rec. 2020 aware?
What is Rec. 2020 really?
When it comes to HDR, there is no getting around Rec. 2020 as the color space to be used, that is clear as far as it goes. It is also clear that there is no display that can actually reproduce this color space. So far nothing new.
HDR-capable displays, such as consumer OLED TVs, can only display DCI-P3. However, this gamut should be contained in a Rec. 2020 container, which is also the first thing our students learn in the HDR master classes.
In order to better understand this connection, we want to clear up the myth "Rec. 2020 is an actual color space", which will one day be able to be represented as an actual display color space.
DCI-P3 is a color space that includes a color space representative of film prints. This is the minimum color space required for digital cinema. Important to know: this is not a container color space. DCI-P3 has become the quasi-standard for all HDR content over the last few years, because this is the color space that should or must actually be used, i.e. it is a display-referred gamut.
Rec. 2020, on the other hand, is initially an ITU recommendation for UHDTV. This recommendation states that the Pointers Gamut should be taken into account.
The Pointers Gamut was published by Michael R. Pointer in 1980 and contains a maximum color space for real surface colors based on 4089 samples. This established a widely recognized target for color rendering. The Pointers Gamut includes all of the colors that we see in the natural world around us. Conversely, the so-called neon colors and colors that are computer-generated, such as in animations, are not included in this color space.
If you compare the DCI-P3 gamut with the pointers gamut, it becomes clear that the DCI-P3 does not contain all the colors of the Pointer Gamut, but already contains values, especially in the critical area of green, which do not occur on natural surfaces.
In contrast to the ITU recommendation for UHDTV, Rec. 709 is the ITU recommendation for HDTV. This recommendation includes the HDTV color space, also known as Rec. 709. Comparing the Pointers gamut to the Rec. 709 gamut shows that the Rec. 709 gamut is much smaller than the Pointers gamut. This is also the reason why it was classified as completely unsuitable for the cinema.
Now we include the Rec. 2020 gamut in our consideration again. If you read the ITU recommendation for Rec. 2020 more closely, you stumble across the word "container". This in turn is due to the fact that displays cannot implement Rec. 2020. In addition, the ITU does not define a minimum scope for UHDTV displays, but with DCI-P3 for digital cinema, so we now have the explanation, there are no displays that can display Rec. 2020, but there are projectors that can display DCI-P3. Therein lies the essential and all-important difference.
Let's come back to the ITU recommendation. The developers of the BT.2020 were well aware that color processing is necessary in all consumer devices, but the goal was the standardization of interchange or container primaries, not of native device primaries. That's a huge difference!
Many colorists are of the opinion that you have to master in the Rec. 2020 gamut when it comes to HDR content, this is simply wrong. As explained above, the Rec. 2020 Gamut is only a recommendation as a container. It is also clear that no display in the world can even begin to show Rec. 2020, and that will not change any time soon.