Ultra HD Alliance announce new 4K specs and logo
When we interviewed Hanno Basse, President of the Ultra HD Alliance, at IFA back in September, he promised a final set of specifications by CES.Today the Ultra HD Alliance kept that promise by announcing a set of requirements and a new logo that are designed to define and deliver a premium Ultra HD 4K experience to consumers. The requirements relate primarily to resolution, bit depth, colour gamut, high dynamic range (HDR), peak luminance and black levels; whilst the specifications themselves are broken down into three distinct headings that are intended to cover the entire 4K entertainment ecosystem. The Ultra HD Alliance were keen to stress that their technical specifications will prioritise image quality but that they also recommend support for the next-generation audio formats.
The first of the specifications is for Devices, which currently covers TVs but, as Hanno Basse told us back in September, the UHD Alliance is also looking at including other displays for certification at a later date. Basse announced that over a dozen TVs have already been certified, with more on the way. To be awarded the Ultra HD Premium Logo a TV must be capable of a 3840 x 2160 resolution, 10-bit colour depth and a wider colour gamut of at least 90% of DCI-P3. The certified TVs must also be able to accept the ITU’s Rec.2020 signal-input interface, which doesn't mean the TV has to actually meet the much wider Rec.2020 colour space, but it does have to be able to accept the Rec.2020 container which will be used for future 4K content.
In terms of HDR the certified TVs have to include the SMPTE ST2084 EOTF (Electro Optical Transfer Function or gamma, as it used to be known) and thus can support HDR10, Dolby Vision and Philips HDR, all of which are supported by 4K Ultra HD Blu-ray. In terms of the actual dynamic range, the specifications cover two possible ranges which basically means there is one for LED TVs and one for OLED TVs. This makes sense and recognises the fact that whilst LED TVs are brighter, OLED TVs can deliver vastly superior black levels. As a result a certified TV can either offer a combination of at least 1,000 nits peak brightness and less than 0.05 nits black level or, alternatively, more than 540 nits peak brightness and 0.0005 nits black level.
The next specification covers Distribution such as 4K Ultra HD Blu-ray, 4K streaming and 4K downloads, and although the Ultra HD Alliance is agnostic as to the method used to deliver content it does have certain requirements. The content must support an image resolution of 3840 x 2160, a minimum 10-bit colour depth, Rec.2020 colour representation and high dynamic range using the SMPTE ST2084 EOTF. Of course given the existing specifications for 4K Ultra HD, the new disc format not only meets these requirements, it easily exceeds them.
Finally, there are specifications for Content Mastering with an image resolution of 3840 x 2160 and a minimum of 10-bit colour depth, Rec.2020 colour representation and high dynamic range using the SMPTE ST2084 EOTF. The Ultra HD Alliance also recommends that mastering displays must be capable of a minimum of 100% of DCI-P3 and a peak brightness of 1,000 nits and a black level of less than 0.03 nits. For both the mastering and distribution channels, the Ultra HD Alliance does not specify a minimum colour gamut or dynamic range, so as not to constrain the artistic intentions of the content creator. However mastering and distribution channels are expected to use the Rec.2020 container even if the actual colour gamut used is less than the potential of the standard.
We can expect to see the first Ultra HD Premium TVs announced as CES, as well as support from various service providers. In addition 4K Ultra HD Blu-ray will also be formally launched with players arriving in the first quarter and over 100 discs planned for the first year.
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