It’s been six long years since the UHD Alliance announced their specifications for Ultra HD Premium requiring devices be able to display no less than 90% of the DCI-P3 color space – in area, not volume. Likewise, the EBU published User Requirements for Video Monitors in Television Production, which proposed now outmoded 2-D diagrams for evaluating color reproduction:
Tolerances of display primaries of Grade 1 HDR monitors are determined so that the following two conditions are satisfied:
Area coverage of the BT.2020 gamut (to be calculated in the xy coordinate) shall be ≥90% for Grade 1A HDR and ≥60% for Grade 1B HDR and Grade 2 HDR. This can be achieved when the distance between the actual primary and D65 white point is equal to the distance between the BT.2020 primary and D65 multiplied by 0.91/2 and 0.61/2, respectively.
Apparently, there’s still no broad consensus in the industry for measuring color performance, with most still using outdated two-dimensional CIE 1931 or CIE 1976 chromaticity diagrams to represent a display’s color capabilities, even though a volumetric description (3-D) that includes the all-important luminance axis makes a heck of a lot more sense for HDR displays.
Back in 2018, Swiss EBU member RTS invited a group of experts from the BBC, CBC, EBU, IRT, NRK, RAI and ZDF to perform a battery of tests on six professional, 1st-gen HDR reference monitors to verify the EBU’s parameters and testing methodology, as well as to learn how high-end monitors stacked up, only to discover that none fell within the Grade 1B tolerance boxes for color gamut. Meanwhile, the latest flagship QD OLED TVs by Sony and Samsung, as well as FSI’s soon to be released XMP550 reference monitor should be able to meet or exceed the EBU’s Grade 1B HDR color gamut spec, as they’re able to achieve ≥80% coverage of Rec.2020 – in color volume, not area! That being the case, isn’t it about time that the UHD Alliance and the EBU updated their testing methodologies?
Photo credit: Nanosys, The Display Show
The Daejeon Chronicles 
All true but the limitations with white LED and OLED are understood. The tools have been out there for plotting the luma component. What matters now is not what testing method the alliance decides on but when will we have the widespread availability of affordable UV emmissives and quantum dot nanocrystals.