New ITU reports help shape next TV revolution: High Dynamic Range (HDR)

ITU’s Radiocommunication Sector (ITU-R) has recently delivered an updated suite of Reports and Recommendations to help broadcasters realise the benefits of High Dynamic Range Television (HDR-TV).

These long-awaited production guidelines and specialist test signals will help bring a rich, new viewing experience to audiences around the world.

HDR delivers an incredible feeling of realism, building further on the superior colour fidelity of ITU’s Ultra-High Definition Television (UHDTV) Recommendation BT.2020 to display even more lifelike images. It will improve levels of detail in dark areas together with brighter highlights to combine to add “sparkle” to the pictures along with a superior impression of depth.

Making the most of HDR-TV

Major broadcasters and content producers around the world are already benefitting from these Reports and Recommendations on HDR-TV and wide-colour gamut in their territories.

The British Broadcasting Corporation (BBC) has now delivered two major Natural History Series Planet Earth II and Blue Planet II in HDR – and all upcoming series will be the same.

The Japan Broadcasting Corporation (NHK – Nippon Hoso Kyokai), the biggest broadcaster in Japan, is currently operating test broadcasting of 4K and 8K UHDTV including HDR via satellite. This will be shifted to regular broadcasting in 2018. The percentage of HDR will also be increased. In this market, HDR is now a must-have in the delivery of high-quality TV programmes to the audience. As programme production shifts from standard dynamic range (SDR) to HDR, the suite of ITU-R texts on HDR-TV provides guidance to content producers on creating good HDR programmes and using SDR materials in HDR programmes.

The Korean Broadcasting System (KBS), the national public broadcaster of South Korea started the regular terrestrial 4K-UHDTV together with HDR broadcasting in Seoul area in May 2017 and UHD broadcasting will be introduced in other metropolitan areas at end of 2017.

The KBS is planning to produce all coverage of the upcoming 2018 PyeongChang Winter Olympics in UHD-4K and HDR quality based on ITU-R Recommendations.

ITU-R HDR-TV and Wide Colour Gamut Standards Developments

At the meeting on 13 October 2017, ITU-R Study Group 6 approved a new Report ITU-R BT.2408 Operational practices in HDR television production – that offers initial guidance on how particular brightness transitions are likely to be perceived by viewers, and can be used to help ensure that the audience is not unduly disturbed by major visual changes that could potentially cause visual fatigue or discomfort when viewed over long periods of time.

This marks the culmination of four years of intensive work and collaboration by dedicated image experts from around the world in ITU-R’s Study Group 6, the group responsible for Broadcasting Service and Radiocommunication broadcasting, including vision, sound, multimedia and data services principally intended for delivery to the general public.

Together with a revision of its more technical sister Report ITU-R BT.2390, clear advice is now available to broadcasters and producers of HDR television content.

Major advances in TV broadcasting

First published in July 2016, Recommendation ITU-R BT.2100 – Image parameter values for high dynamic range television for use in production and international programme exchange – represented a major advance in television broadcasting.

The HDR Recommendation allows programme makers to select from a range of options according to programme genre or target market. BT.2100 offers a choice between Perceptual Quantization (PQ) which achieves a very wide range of brightness levels using a transfer function that is finely tuned to match the human visual system, and Hybrid Log-Gamma (HLG) that offers a degree of compatibility with legacy displays by more closely matching the previously established television transfer curves.

There is also a choice of resolutions or levels of detail: HDTV (1920 by 1080), UHDTV ‘4K’ (3840 by 2160) and UHD ‘8K’ (7680 by 4320) – all using the progressive image format with extended colour gamut and a range of frame-rates in line with ITU’s UHDTV Recommendation BT.2020. This flexibility allows broadcasters to select the technology according to the target audience, the delivery platform, and the long-term value of the content. It also offers a migration path from extended-quality HD all the way up to ‘8K’ resolution.

What’s next?

For some years to come, the majority of television viewers will continue to watch programmes on consumer displays that have not been designed to display HDR images. It is important that SDR to HDR conversion is not only easy to do, but is also of high quality.

Further guidance is being developed on methods to convert programmes mastered in HDR for delivery to current high definition and standard definition distribution systems; also how to make the most of existing SDR content by increasing its displayable dynamic range, so far as possible, when incorporated in HDR programmes.

Study Group 6 will continue to study how broadcasting can take maximum advantage of new technologies. As well as HDR, other exciting new areas such as Augmented Reality (AR), Virtual Reality (VR) and Artificial Intelligence (AI) can potentially be used to offer innovative and interesting experiences for the benefit of broadcasters and their audiences.

Dr. Yukihiro NISHIDA, Chairman Study Group 6 Mr. Paul GARDINER, Chairman Working Party 6B Mr. Andy QUESTED, Chairman Working Party 6C