What is High Dynamic Range (HDR) Video?
High dynamic range (HDR) video technology is the next great leap forward to reproducing what the naked eye sees in colors and in contrast between the brightest whites and the darkest blacks. HDR video is about recreating image realism from camera through postproduction to distribution and display.
Technically speaking, HDR video standards encompass more than just higher peak brightness and lower black levels. HDR also supports a wider color palette, new transfer functions, greater bit depth, and static and/or dynamic metadata.
The good news is that HDR video is here to stay. The bad news is that a lack of industry consensus around HDR video formats will be around for a while too.
With multiple formats, standards, single and dual-layer implementations, and different display options, the current HDR video landscape presents few hard-and-fast rules and a broad range of prospects. Our goal is to help you extract something practical and useful from the map of possibilities HDR video offers.
How Does HDR Improve Video Quality?
Seeing is believing, but because your eyes are focused on a web page and not the monitors in a state-of-the-art video experience lab, perhaps the easiest way to explain HDR video in words is to outline what it does. Here’s how HDR video technology works:
- Creates more-defined contrasts and richer colors
- Increases dynamic range (aka, peak brightness and black levels)
- Expands color space (wide color gamut)
- Improves image fidelity (10-bit color depth and 1024 color shades)
- Updates to an opto-electronic transfer function
- Offers static and dynamic metadata
All combined, these add up to one significant result: HDR video delivers the kind of wow-factor image quality improvement that viewers covet once they experience it. See below for a comparison between SDR and HDR video image quality.
What Should I Know About HDR Video Formats?
HDR video is a mix of proprietary technology, open standards, technical recommendations, and industry guidelines. While HDR formats have been standardized, there are questions regarding mastering values for HDR content—such as peak white values, mid-gray tone values, color gamut/space issues, and metadata carriage. With that in mind, here’s what you see when you survey the HDR video format landscape.
|Format||Proposed By||Metadata||Transfer Function||Target(s)|
|Advanced HDR||Technicolor and Philips||Dynamic||HLG or PQ||Broadcast TV, Blu-ray and VOD|
|Dolby Vision||Dolby Laboratories||Dynamic||PQ||Broadcast TV, Blu-ray and VOD (separate implementation for Digital Cinema)|
|HDR10||Dolby, adopted as SMPTE ST-2084||Static||PQ||Broadcast TV, Blu-ray and VOD|
|HDR10 with dynamic metadata||SMPTE 2094-x
-10 = Dolby
-20 = Philips
-30 = Technicolor
-40 = Samsung
|Dynamic||PQ||Broadcast TV, Blu-ray and VOD|
20th Century Fox,
|Dynamic||PQ||Broadcast TV, Blu-Ray and VOD|
|Hybrid Log Gamma (HLG)||BBC and NHK||None||HLG||Broadcast TV|
LED, OLED and Why HDR Video is “Nit” Picky about Color
Notice the difference in the color space graphic. The Rec.2020 color space expands the range of displayed color space significantly, resulting in much more vivid, realistic colors that HDR video can display. Rec.2020 color space takes advantage of the capabilities of LED and OLED displays to show brighter, more saturated colors – as our eyes behold them in real life.
Most HDR video displays today are 1000 nits. What are nits? Nits are a numeric representation of the peak white color volume, or luminance, measured in candelas per meter squared. Standard Dynamic Range displays are typically 100 nits, whereas the SMPTE ST-2084 standard specifies luminance up to 10,000 nits.
What is the Industry Outlook for Bringing HDR Video to Market?
Bringing HDR video into the mainstream will require buy in from stakeholders at every step of the media supply chain, from content creation to playback. As things stand today, many pay TV providers, OTT service providers, and broadcasters are in wait-and-see mode.
On the other hand, some companies have already taken the leap, as is the case with many streaming video providers and studios making HDR video content available.
Meanwhile, a few matters are currently influencing broad marketplace adoption of HDR video:
- The number of HDR-capable displays available
- The type of HDR video formats these displays support
- Backward compatibility with legacy displays that use the Rec.709 color space
- Availability of HDR content from studios and various distributors including OTT services, broadcasters, and pay TV operators
HDR video is desirable and inevitable, but its roll out will be gradual. For example, in the United States, Dish, DirecTV, and Comcast delivered the PyeongChang 2018 Olympic Winter Games broadcasts in 4K and HDR, but only…
- With certain equipment
- For just a few events
- With a time delay