Finally—HDR is here, and content is being graded for it. UHD/4K isn’t only about pixel count any more!
In my view, one of the biggest stories at this week’s National Association of Broadcasters (NAB) convention in Las Vegas, NV, was high dynamic range (HDR) in terms of capture, grading, and display. On the display side of things, many companies were showing prototypes and, in some cases, currently or nearly available flat panels capable of fully reproducing an HDR video signal. Granted, most were professional monitors that cost in the five figures for a screen typically measuring 30 inches or less. But those products often point the way to consumer variations—and there are even a few consumer models being demo’d with content specifically graded for HDR.
As anyone who follows my work knows, I think HDR is the most important aspect of UHD/4K, far more important than pixel count. Yet virtually all UHDTVs sold today do not have HDR capabilities. (Of course, the Samsung SUHD TVs and newly re-announced Vizio Reference series do, and there was a prototype of a Sony HDR consumer flat panel at NAB.) So I was thrilled to see so many HDR displays at the show. It’s great to know that the content creators are starting to work with HDR, which can only be good for content consumers.
Among the important parameters of HDR displays is their peak brightness, which is typically greater than the peak brightness of standard dynamic-range (SDR) displays. (SDR consumer content is graded to a peak brightness of 100 nits or about 30 foot-lamberts, while most HDR displays can produce a peak brightness of 1000 nits or more.) Many viewers are concerned that high peak brightness means a searingly bright picture, especially in a dark room, but I have not found that to be a problem. Instead, it generally means that small areas of high brightness can be rendered accurately with visible detail along with areas of lower brightness in the same image.
High peak brightness also means that color can be rendered more accurately over a wider range of luminance. Colors often wash out to white as they approach the display’s peak brightness, so having that extra headroom helps keep colors true even in high-brightness areas of the image. Speaking of color, most of the HDR displays at the show had color gamuts wider than BT.709. Most encompassed DCI-P3, the commercial-cinema color gamut, while a couple claimed to reach all the way to BT.2020.
HDR displays require more than 8 bits per primary color to avoid banding artifacts; most of the examples on the show floor used 10 bits. A related factor is the gamma curve, which defines how the light output from the display is related to the brightness level in the signal; this is also known as the electro-optical transfer function (EOTF). Most of the HDR displays at NAB use the PQ EOTF, which was developed by Dolby and is now part of the SMPTE ST.2084 HDR standard.
I always enjoy taking product shots at trade shows, but accurate photos of HDR displays are impossible without an HDR camera, which I don’t have. So the photos I’m sharing here do not accurately depict what these displays actually looked like. I include them only as an avatar for each display I describe.
The shot at the top of this thread is from the Arri booth. Footage shot on the Arri Alexa 65 and Amira 4K HDR cameras was displayed on a Samsung UE65JS9500 SUHD consumer TV, which can achieve a peak brightness of 1000 nits. The JS9500 uses the SMPTE ST.2084 HDR standard with PQ to render HDR content with 10 bits per color. Like all the HDR displays I saw, this one looked spectacular.
My favorite HDR flat panel at the show was this 4K LED-FALD LCD prototype by Canon, which has a peak brightness of 2000 nits and uses a proprietary HDR system based on PQ; no one would reveal to me the bit depth of this 30-inch-wide display, which encompasses the BT.2020 color gamut. The demo footage included shots inside a dimly lit bar with a window to a very bright day outside; on an SDR display with SDR content—or in an SDR photo of those shots—any details in the window would be totally blown out, but in this demo, the details outside and inside the bar were equally clear. Plus, the red of the Mustang seen here was definitely outside the boundaries of BT.709. It was jaw-dropping.
Canon was also showing two 4K HDR production monitors, including the new 24″ DP-V2410 seen here, which is scheduled for release in November. Its peak brightness is “only” 400 nits with 10 bits per color using the SMPTE ST.2084 HDR standard, and its color gamut is DCI-P3. The existing 30″ DP-V3010 will get a firmware upgrade in November to allow HDR up to 200 nits.
Sony had two samples of its 4K OLED monitor, the BVM-X300, set up side by side in a blacked-out area. One was showing SDR-graded content (left), while the other was showing HDR-graded content (right). The X300 has a peak brightness of 1000 nits using 10 bits per color and Sony’s S-Log3 gamma curve, and it can reproduce the BT.2020 color gamut. The HDR version was obviously brighter, and the colors were more saturated; it looked quite amazing, as I would expect for $42,000!
Sony was also demonstrating a prototype 75″ HDR consumer UHDTV (right) showing HDR-graded content next to a 70″ X850B (left) showing the same content graded for SDR. The prototype can produce up to 1000 nits of peak brightness using 10 bits per color and the SMPTE ST.2084 HDR standard; I was told the color gamut is “P3-ish.” The difference between these two displays was not as dramatic as the OLEDs—the X850B might have been stretching the dynamic range as Sony TVs can do—but I still preferred the prototype. I won’t be surprised if it’s introduced as a product at CES 2016.
Dolby was one of the first companies out of the HDR gate with Dolby Vision, which uses the PQ curve and 12 bits per color. Seen here are two samples of the company’s second-generation, 1080p Dolby Vision monitor (32″) with 2000 nits of peak brightness encompassing the P3 color gamut. The one on the left is showing SDR-graded content, while the one on the right is showing HDR content; as with most such demos, the HDR image looked far superior to the SDR image, with much more detail and no blooming or washed-out colors despite the brighter image.
The company’s first Dolby Vision 1080p monitor has been demo’d for a while now, and Dolby claims it’s the brightest display in the world at 4000 nits. It was also shown next to an SDR monitor—in this case, a Dolby PRM-4220 reference monitor—and it was so bright, I couldn’t get a good photo of it without severely underexposing the SDR monitor. Even so, I did not find it uncomfortable to view in the dark environment.
Both Dolby Vision monitors are LED-FALD LCD flat panels, and each LED in the array is independently dimmable. In the original one, the LEDs are white, while the new one uses blue LEDs firing through a quantum-dot film, which uses less power and provides a potentially wider color gamut.
Also in the Dolby booth were two 65″ Vizio Reference Series TVs, which implement Dolby Vision and were recently re-introduced at a press event in New York. The one seen here was showing some Dolby-generated HDR game footage—there is much more detail in the bright areas than you can see in this photo—while the other one was streaming an HDR-graded version of The Lego Movie from Vudu. Sweet!
JVC had an interesting HDR demo. An HDR-capable camera in the center of this photo was trained on a still-life scene to the right, and the live signal was displayed on a prototype 1080p HDR display to the left—in this case, a 36″ D-ILA rear-projection setup. I was told it can generate up to 2500 nits of peak brightness with 10 bits per color using the SMPTE ST.2084 HDR standard with PQ gamma and reproduce the P3 color gamut. JVC wanted to emphasize that D-ILA technology naturally exhibits high dynamic range. And I thought rear projection was dead!