UHD Alliance Unveils 'Ultra HD Premium' Spec

The UHD Alliance is an organization of 35 companies that came together a year ago to set standards for Ultra HD displays. On the evening before press day, they held a press conference to discuss their goals and accomplishments.

The standards they’ve set for UHD involve 4K resolution, high dynamic range (HDR) wide color gamut, enhanced color bit depth, high frame rate, and immersive audio. The latter appear to be optional. No mention was made of high frame rate (though it was listed in the press release we received), and immersive audio is, in fact, available even now as Dolby Atmos and DTS:X, neither of which are exclusive to UHD (they are currently available on a number of Blu-rays).

The major accomplishment of the organization appears to be the establishment of an “Ultra HD Premium” logo. For a set to be sold under this logo, it must meet certain standards. It must be capable of 4K (3840 x 2160) resolution, 10-bits per color bit depth, and high dynamic range (HDR) at the SMPTE standard EOTF (gamma) of ST2084, in addition to exceeding 90 percent of the P3 color gamut.

The HDR spec is intriguing, as it allows the manufacturer to choose one of two standards for any given set:

More than 1000 nits peak brightness and less than 0.05nits black level.
More than 540 nits peak brightness and less than 0.0005 nits black level.

This disparity appears to be designed to allow for the relative capabilities of LCD and OLED displays (OLED cannot go nearly as bright as LCD, but can offer far deeper blacks—0.0005 is, essentially, total black). The spec does not specify which HDR format the display or sources must meet.

For distribution media, the standard for color gamut is BT.2020. This cannot yet be achieved by commercial displays, and also remains somewhat controversial for reasons having to do with individual variations in human color perception.

UHD sets that don’t yet have all of these features can still be marketed, but cannot carry the Ultra HD Premium logo. The term Ultra HD alone, without Premium, guarantees nothing beyond 4K resolution.

Key personnel from Warner Brothers, 20th Century Fox, Sony Pictures, and Universal Studios expressed enthusiasm for the format as they discussed plans for Ultra HD Premium source material. While they were a little vague on their plans for the delivery medium (streaming, downloads, or Ultra HD Blu-ray) they agreed that there should be about 100 titles (new films and catalog titles) available in the Ultra HD format by the end of 2016. It appeared, however, that many of these titles will be backloaded—that is, available only later in the year.