HDR holds the key to better images


SCREEN AFRICA EXCLUSIVE: Consumers have long judged video content by the visible quality of the image they see on a screen. With newer high-resolution formats now available on standard consumer-grade devices, viewers have naturally developed a hunger for first-class quality, which explains why they have such high expectations for better and better images.

Over the years, we’ve witnessed the shift from black-and-white to colour, from SD to HD, from analogue to digital, and now we are seeing simultaneous interest in both 4K UHD and HDR. Looking for a superior viewing experience, consumers are investing in new displays that can support these latest formats. Initial reactions to 4K UHD and HDR content indicate that consumers are impressed with the noticeable difference they see in the quality of programming; the colours pop and the details stand out more in a wider variety of scenes. This demand on the part of consumers – and the advertisers trying to reach them – is pushing content producers to adopt 4K UHD and HDR technologies.

4K UHD increases the number of pixels, resulting in a larger field of view for long shots or increased detail in close-ups. However, while consumers undoubtedly enjoy a much richer viewing experience in 4K UHD, the additional resolution alone is not enough – particularly when you consider the screen size that most of them are accessing content on. More pixels in an image requires a much larger screen at the same viewing distance to see a noticeable difference in the content. This is where HDR comes in.

HDR is generally recognised as the next big thing in content delivery, delivering an immediate – and perceivable – benefit to the consumer. Thanks to its contrast ratio, which is closer to the conditions found in real life, HDR allows image reproduction that is much closer to reality.

Consumer trends indicate that HDR is a good bet for content producers. Shipments of HDR TV sets are forecast to surpass HD units by 2020 and reach 245 million units in 2022, representing a market that will be worth around 36.82 billion by that same year. By combining 4K UHD and HDR, broadcasters can deliver the best images possible in the industry today that create truly immersive and lifelike experiences for viewers.

HDR also benefits content creators in that the format enables more dependable results under difficult shooting conditions. Its wide contrast range is better able to capture much more detail in the brighter areas of the picture in environments with irregular lighting or partial shade, found at many outside broadcast productions.

It’s not just in the context of 4K UHD that HDR can make a difference. HDR is fully format independent and does not need any specialised viewing conditions – such as the minimum screen size and proper viewing distances required for 4K UHD – to show its advantages. The ability to produce HDR content in HD removes the significant bandwidth requirements needed for HDR in 4K UHD and can be more quickly deployed. For many broadcasters, adding HDR to 1080p HD footage is an attractive, cost-effective strategy. From a viewer perspective, there is still a stunning improvement in image quality, and disruption to existing workflows is minimal.

Bringing HDR into the workflow

For broadcasters and content creators, embracing an HDR workflow process raises a number of questions and poses some challenges. Most notable is the need for a parallel SDR/HDR production workflow – one where the signal can be adapted with up/down mapping as required to mix and match incoming content formats and output signals, without sacrificing any quality. For example, operators may need to integrate existing SDR content into new HDR productions or may need to send HDR content to SDR multiviewing screens in a studio. Many broadcasters reserve HDR for their premium channels but don’t want the expense of a separate production chain for generally broadcast SDR assets. In any case, the producer’s intent for each individual signal must be maintained.

One of the big hurdles to widespread deployment – as it always is with any new technology – is standards. ITU-R, the radiocommunication sector of the international telecommunication union, have specified in their Recommendation ITU-R BT.2100 “Image parameter values for high dynamic range television for use in production and international programme exchange” two different standards for HDR – Hybrid-Log Gamma (HLG) and Perceptual Quantisation (PQ) or Dolby Vision.

Grass Valley, a Belden Brand, offers a portfolio of HDR-enabled Live production solutions that includes cameras, production switchers, servers, routers, up/down mapping cards and multiviewers. To provide the best possible picture quality, either HD or 4K UHD images are captured and used across the production chain in their native PQ or HLG format. That content is simultaneously delivered in HD or 4K UHD, SDR or HDR through a best-in-class down-scaling/down-mapping conversion at the end of the production chain. Using not only the most, but also the best pixels throughout the production and a single conversion ensures the best quality picture possible. An added benefit for many content producers who must rapidly adapt to new production environments at each event, Grass Valley supports all of those formats from the same hardware, preserving the producer’s investment and skill sets from program to program.

An upward trend ahead

Looking forward, we are expecting a rise in 4K UHD and HDR uptake across sports and entertainment production. In recent months, we have seen significant investment coming from broadcasters as well as production companies, outside broadcasting and rental houses globally – and we expect this trend to continue in the months ahead.

Written by Chris Merrill (director of Product Marketing) and Klaus Weber (principal, Camera Solutions and Technology) at Grass Valley


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