By PURPLELEC | 14 April 2025 | 0 Comments
HDR Technology: From Contrast Enhancement to Format Competition
Not long ago, the video display industry was still exhilarated by the high-definition visual experience brought by 4K resolution, and the future of 8K was even more exciting. However, the hottest trend in the TV industry today is the increasing popularity of High Dynamic Range (HDR) technology, which has also enhanced the contrast and color depth of true 4K itself.
Contrast is crucial to the human eye, but TV screens and other displays have long suffered from uneven blacks and shadow details. HDR aims to address these issues. This technology can significantly improve contrast and present more realistic visual effects, marking a major leap forward for home 4K TVs. Today, all non-HDR content is referred to as SDR (Standard Dynamic Range).
Although 4K Ultra HD TVs have higher resolutions and more pixels than previous standards, HDR TVs can achieve more with the same number of pixels. HDR typically focuses more on low-light areas rather than highlights, but HDR TVs have a wider depth range. HDR can reveal color details in low-light areas, ensuring that shadow details are not crushed while not obscuring highlights. In short, HDR makes darks darker, lights brighter, and creates additional tones in post-production to optimize the contrast of the display and add detail in an expanded color space. This not only enhances the impact of the image but also adds extra vitality.
Static HDR and Dynamic HDR
Moreover, HDR represents a significant improvement over SDR, but in fact, HDR comes in two varieties—Static HDR and Dynamic HDR—each offering different levels of visual enhancement. While both HDR standards allow movies to fully utilize HDR's expanded contrast range, brightness levels, and higher detail levels, only Dynamic HDR can achieve perfect scene-by-scene or even frame-by-frame rendering. In this way, Dynamic HDR ensures that every moment of the video is presented with ideal visual brightness, which is crucial for bringing the director's "vision" to the TV, as significant contrast changes have become part of content conception and shooting. On the other hand, Static HDR content has only one HDR style because static metadata requires compromises across all scenes. Nevertheless, Static HDR is still HDR and remains a significant improvement over SDR.
HDR Formats and Dominance Contest
Currently, there are three main HDR formats, each with varying degrees of industry support and content, along with two emerging formats.
HDR10
The most popular format is HDR10, an open standard created by the Consumer Technology Association (CTA) in 2015. It has become the de facto standard because it is free to use, widely available, and can be decoded by all HDR TVs. HDR10 has been adopted by most streaming services and is the benchmark HDR technology for 4K Ultra HD Blu-ray. Additionally, Dell, LG, Samsung, Sharp, Sony, and Vizio all produce TVs/monitors that use HDR10. Despite its leading position in available content and consumer products, the format's main drawback is that it only supports Static HDR. It also does not support backward compatibility with SDR TVs, which limits its practical appeal to broadcasters.
Dolby Vision
Dolby has its own version of HDR called Dolby Vision, which goes a step further than HDR10 by offering Dynamic HDR. Streaming services like Netflix and iTunes support this format. Since the first Dolby Vision TVs were released in 2017, this format has become increasingly popular. It is a proprietary technology, and although companies must pay Dolby to use it, Dolby in turn provides resources and tools to optimizers so that Dolby Vision content is optimized on their branded TVs. In terms of content, companies like Sony, Universal Pictures, Paramount, and Time Warner have provided support.
Hybrid Log-Gamma (HLG)
Another HDR format is Hybrid Log-Gamma (HLG). It was jointly developed by the British Broadcasting Corporation (BBC) and Japan's NHK. Although this format's picture quality is not as good as some other HDR formats, its advantage lies in being the only mainstream format that is backward compatible with SDR TVs. This is because HLG does not use metadata but instead uses the same gamma curve as SDR signals and adds a brighter logarithmic curve on top of the signal. Not using metadata means that HLG HDR can be produced using the same workflow as traditional TVs, making it more suitable for broadcast TV. In terms of the dominance contest, having a format that works on both old and new TVs is obviously beneficial for broadcasters, as most households will continue to watch content on non-HDR TVs for many years to come. BBC iPlayer, DirecTV, Freeview Play, and YouTube all support this format.
HDR10+
In addition to these three formats, another newer format is HDR10+. This is an open standard announced by Samsung and Amazon in 2017. The main advantage of HDR10+ is that it has dynamic metadata, which means there are no compromises when viewing the darkest or brightest scenes. Additionally, HDR10+ is backward compatible with devices using HDR10 encoders. Although Samsung's format is ostensibly royalty-free, some industry insiders have expressed concerns, but support appears to be growing nonetheless. Samsung, Panasonic, and 20th Century Fox are all members of the HDR10+ Alliance, while Amazon Video offers HDR10+ content. Warner Bros. and Panasonic's Ultra HD Blu-ray players also support the HDR10+ standard.
SL-HDR1
Finally, SL-HDR1 is another HDR standard developed jointly by STMicroelectronics, Philips International B.V., and Technicolor R&D France, and is a proprietary technology. Its main advantage is that it uses both static and dynamic metadata and is fully backward compatible with SDR TVs and networks, giving it an edge with broadcasters. This means that HDR signals reconstructed from SDR video streams can be transmitted using existing distribution networks and services.
IT maintenance dilemmas with IP and LCD console KVM failures
KVM Switches: The Ultimate Solution for Multi-Device Management
Leave a Reply
Your email address will not be published.Required fields are marked. *