The number one thing commercial display manufacturers and customers should care about is delivering the most lifelike digital experience possible. Concerns over price, longevity, and versatility matter as well but the on-screen experience is paramount. For years, improvements to display performance like adding pixels and quickening frame rates have underserved one crucial area separating digital content from real life: color. More pixels bring sharper detail and accelerated frame rates smooth movement but these upgrades misdiagnose what makes content look most lifelike. It’s not the clear definition of a cloud or the subtle pacing of its movement across the screen that suspends audiences’ disbelief; it’s the fact that the blue skies behind the cloud look exactly as they do outside. For decades, these blue skies in particular have proven exceptionally difficult to capture accurately, thanks in large part to the restrictive legacy of outdated cathode ray tube (CRT) technology. Blessedly, a new image formatting technology has come around that is transforming the way lifelike content is created, delivered, and displayed. It’s called High-Dynamic-Range video and you’ve almost certainly heard of it, likely from manufacturers advertising they are capable of showing it. Like with any technological advancement however, customers need to be wise in sifting fact from fiction. The technology can be confusing and many display technologies advertise they can handle HDR when really all they mean is they can receive (but not display) it. Consumers can’t know the truth of these claims until they are tested in person. Before saying whether customers should buy what manufacturers are selling, let’s first discuss what HDR is and what role it will play moving forward.
Blue Skies Ahead with HDR
High-Dynamic-Range video, or HDR as you’ve likely read it, describes video with a greater dynamic range than that of standard-dynamic-range (SDR) video, with dynamic range defined as the difference between the brightest and darkest points of an image. Up to this point, televisions using SDR standards limit maximum brightness to around 100 nits and minimum brightness to about 0.117 nits, a range influenced by the days when televisions were built using CRT technology. One of its most noticeable casualties of this limited range is the saturation of bright colors, illustrated fittingly by blue skies. Content creators and audiences expect a bright, blue sky to be exactly that: bright and blue. With a maximum brightness of 100 nits however these skies are forced to either reduce their brightness or to reduce their saturation, since the brighter a color gets under this limit, the whiter it will become. The same principle applies at the lower bound of brightness for extremely dark content. This results in blown-out bright areas, unnatural blending in shadowy areas, and banding, the color striping audiences see when a display can’t smoothly grade from one shade or tint to another.
The expanded luminance range of HDR content reveals greater detail in both shadowy areas and in blown-out bright areas and thus more closely imitates the way our own eyes behave when at the upper and lower bounds of our perception. Further, HDR widens and deepens the spectrum of achievable colors. One formal HDR formatting standard worth acknowledging is the open-source HDR10, which uses the Rec.2020 color space and a bit depth of 10-bits. The Rec.2020 color space expands upon the more common color gamuts of Rec.709 (used by HDTV) and DCI-P3 (used in the film industry) and edges digital content closer to the limits of the human eye, though sparingly few display technologies are capable of hitting it. Many can accept it, but hardly any can actually reach its full spectrum. Changing from the SDR bit depth of 8-bits to 10-bits allows HDR content to exhibit more refined grayscale to better differentiate separate shades and tints of similar colors. That 8-bit color can accommodate about 16.78 million colors sounds impressive until you realize that 10-bit color can hit 1.07 billion, and the additional intermediary color combinations help eliminate banding by adding more distinct variations between each color. HDR-10 also calls for the communication of static metadata from content to the display it’s to be played on. Software interprets details like Maximum Frame Average Light Level and Maximum Content Light Level to adapt the color calibration of the content and display it to its truest nature. More advanced HDR formats like HDR10+ and Dolby Vision make use of dynamic metadata instead of static to further refine brightness levels on a frame-by-frame basis.
Receiving HDR =/= Displaying HDR
These remarkable benefits of HDR are lost unless a display can accommodate them however, and most displays fail to do so. In-home televisions are inching closer towards being able to display HDR content but since most of those products are backlit LCD displays they’ll likely fail to markedly improve the brightness bounds to really let HDR content make its impact. Direct-view out-of-home LED displays are just about the only solutions capable of hitting the upper brightness bound for an extended period of time, but even the best of these displays struggle to reach the full extent of the Rec.2020 color space. HDR content will still look better than SDR on most of these displays, but that’s not entirely the point.
Businesses and organizations who make the decision to purchase and install a digital display solution are not simply buying something off the rack. They are partnering with a manufacturer like Nanolumens to arrive at a fully customized solution that is built to fit a specific space and a specific purpose. If full HDR compatibility is something a customer expects, manufacturers should expect to explain whether or not they can deliver it in full. As noted earlier, being able to receive HDR content is an entirely different task than being able to actually show it in its true form, so customers need to press manufacturers to clarify what their claims are saying. The day where HDR content is on every display is still in the future, so right now consumers should turn to the manufacturers they trust if they’re targeting an HDR experience for their audience. We at Nanolumens would love to help you do that, so if you’d like to learn more about how HDR works and how displays are adapting to it, give us a call today!