Janet Lafleur, product marketing, Quantum on why HDR will make all the difference to 4K take up, but storage could prove to be a headache
The notion that high-resolution means better video quality has helped to fuel 4K production and distribution, as well as the manufacture of 4K television sets.
With 4K content beginning to make its way into the home, the format’s massive increase in pixels simply isn’t wowing audiences the way HD had done before when the viewing experience noticeably improved from SD. This is largely because most people are unlikely to reduce the distance from their sofa to their screen to really notice the difference.
What’s becoming clear is that other enhancements to image quality hold far more potential to impress viewers, and high dynamic range (HDR) could be the technology that will make 4K — and even 2K — content really stand out. The move from the current 8-bit depth standard to a 10-bit depth for HDR TV expands colour precision from 256 shades to 1023 shades. So with darks becoming darker, lights becoming lighter and more fine-grained variation across the spectrum, each pixel benefits from more depth for a broader range of values.
While 4K and even larger formats generally require a larger screen size to prove effective, HDR’s advantages are plainly visible on a screen of any size, which is what makes it so attractive. As leading media companies like Netflix move to bring ever-greater realism to viewers’ screens, they are examining the improvements that HDR can bring to every pixel – in 2K or 4K.
While 4K continues to be a primary focus for many content creators and providers, the stunning impact and much lower bandwidth requirement of HDR 2K content makes it a compelling alternative. Where 4K requires an extra 12 Mb/s or so of broadband speed for streaming, a 2K HDR stream can fit within the 10Mbps connection that many households have today, giving consumers a much improved viewing experience without upgrading their service.
The drawback of higher resolution is that without compression, the jump from HD to 4K nearly quadruples storage requirements if both frame rates and pixel depth are kept constant. HDR demands additional storage capacity beyond that. By capturing two streams at different exposures, HDR motion cameras require twice the capacity for capture, ingest and editing storage. On top of that, creating and delivering 10-bit content for 4K displays requires an extra 25 percent at each stage of the workflow. And since most HDR cameras can capture in 16-bit, many content creators will edit and archive at that rate for future-proofing, which means doubling capacity rather than simply increasing it by 25 percent.
The good news is that HDR capabilities are making their way into 4K TVs that consumers can buy now, video streaming services are getting on board, and 4K displays generally do a good job up-rezzing from 2K. The bad news is that broadcast HDR content lags behind. As more consumers switch to HDR-capable TVs; however, the momentum is likely to pick up and fuel large-scale equipment and workflow upgrades to support HDR.
By radically boosting image quality even where bandwidth is limited, HDR has the greatest potential to deliver the beauty that’s widely expected of 4K. Viewers may not be able distinguish between more pixels and better pixels, but in the long run it may not matter. With the new Ultra HD standard, the industry can deliver both, but the workflows for content creation and delivery must be ready.
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