What Is HLG?
HLG is an HDR standard designed to both add HDR compatibility to broadcast TV signals and maintain a similar simplicity for the broadcast data itself, without adding much in the way of additional bandwidth demands. It allows broadcasters to transmit a signal with a wide dynamic range supported by HDR and SDR televisions, massively reducing the cost and complexity of the broadcast signal. HLG is royalty-free, unlike more niche standards like Dolby Vision, and unlike the other HDR standards, it doesn’t use metadata to tell the TV how to display the HDR content.
Do I Need HLG in My New TV?
If you plan to watch broadcast TV on your new television, it’s a good idea to get one with HLG support, as it is gradually seeing increased adoption among broadcasters. For example, Sky UK announced in 2020 that its Sky Q satellite TV box would support HLG content moving forward. Some streaming content also takes advantage of the HLG HDR standard. For example, you can stream the BBC’s Planet Earth II (some segments) and Blue Planet II series from its iPlayer app with HLG HDR.
How Does HLG Work?
Although the result is similar to other HDR standards, HLG HDR is designed for broadcast television rather than predominantly for streaming or local media playback. However, it does work a little differently to HDR10, HDR10+, and Dolby Vision. HLG encodes its HDR data into a single wide-range signal compatible with both SDR and HDR televisions. As a result, other HDR standards are not supported at all by SDR TVs. That cuts the amount of transmission bandwidth required in half for broadcast content. However, SDR TVs that try to play HLG content will display a standard image—though there is some potential for additional detail in highlights. HLG HDR achieves its improved dynamic range without the use of metadata, too. Where Dolby Vision and HDR 10+ use metadata to inform a display of how, when, and where to adjust brightness accordingly, HLG forgoes that information is often lost during a broadcast.
What TVs Support HLG?
Most recent TVs from Sony, LG, Samsung, and Panasonic have HLG support across most flagship models. High-end TVs, in general, tend to support it alongside other HDR standards too. However, it isn’t as prevalent as HDR10, especially in more niche manufacturers and projectors, although it is gaining in popularity with each passing year.
