This morning the VESA is rolling out an update to the standard body’s DisplayHDR monitor performance standard that’s focused on expanding the specification to cover OLED displays. Dubbed DisplayHDR True Black, the new performance tiers to the DisplayHDR standard are intended for OLED and other emissive displays, laying out the levels of display performance that the association believes are appropriate for consumer HDR displays.

This update comes just over a year after the original DisplayHDR standard was launched. Intended to simplify the market for HDR displays, DisplayHDR sets a number of tiers of increasing performance, with each higher tier requiring better monitor technology and delivering a better HDR experience as a result. At the time of DisplayHDR’s launch, the VESA opted to focus on LCDs, as these displays were already in the PC market and were what the association had the most experience with. The end result was the DisplayHDR 400, 600, and 1000 standards, which covered a range of monitor designs that essentially stretched from not-very-HDR to cutting-edge full array local dimming displays.

The DisplayHDR True Black update in turn adds two more tiers to the DisplayHDR standard: DisplayHDR 400 True Black, and DisplayHDR 500 True Black. Like the tiers for LCDs, the True Black tiers are divided up based on performance; though the gap isn’t quite as big as with the LCD tiers. The end result is that displays reaching these standards, besides meeting the DisplayHDR specification’s baseline requirements, can also hit a peak brightness of 400 nits and 500 nits respectively.

The need for separate tiers for OLEDs – and other future emissive technologies like microLEDs – is rooted in the fact that HDR itself is as much (or more) about dynamic range as it is absolute maximum and minimum brightness. While LCDs can offer the necessary contrast ratios with the right backlighting technology, they are still backlit displays, meaning that they can’t quite hit black since they’re always illuminated to a degree. OLEDs, on the other hands, can hit almost perfect black levels since the pixels can simply be turned off entirely – hence the True Black moniker – which means these displays need to be measured on a different scale. Conversely, while LCDs can sustain incredible 600+ nit brightness levels over the whole screen, OLED technology can only burst to these levels for short periods of time, so the maximum brightness offered by OLED displays isn’t quite in sync either with HDR LCDs.

Overall the DisplayHDR standard covers a number of performance requirements (the VESA’s full chart is below), however as OLED displays are currently a high-end solution, DisplayHDR True Black displays are primarily competing with DisplayHDR 1000 displays. So I’ve distilled the important points to the below.

DisplayHDR Luminance Specification Comparison
  DHDR 1000 DHDR 500 TB DHDR 400 TB
White - 10% Center Patch
Minimum Brightness
1000 nits 500 nits 400 nits
White - Full Screen Flash
Minimum Brightness
1000 nits 300 nits 250 nits
White - Full Screen Sustained
Minimum Brightness
600 nits 300 nits 250 nits
Black - Corner
Maximum Brightness
0.05 nits 0.0005 nits 0.0005 nits

In short, DispayHDR True Black mandates a maximum black level performance of 0.0005 nits, 1/100th the brightness of a DisplayHDR 1000 display. While technically not 0 for practical measurement reasons (measuring nothing is surprisingly hard), in practice the standard fully expects and exploits the fact that OLED displays can turn off individual pixels to achieve perfect blacks. Conversely, the standard calls for a maximum of 500 or 400 nits respectively for a 10% patch of full white, and only 300/250 nits for the full screen. This is around half of what a DisplayHDR 1000 display can offer, which is 1000 nits for everything short of a long-duration full screen image.

The net result is that the new tiers reflect what we already know about each technology: OLEDs can get very dark, but they can’t get super bright. Meanwhile LCDs can’t hit pitch black, but they can get incredibly bright. But both can offer extensive dynamic ranges – over 20,000:1 for LCDs and 1,000,000:1 for OLEDs – allowing both to deliver the “high” part of high dynamic range. And now the standard can express these differences while requiring both display types to offer appropriate contrast ratios.

Meanwhile it’s interesting to note that the DisplayHDR True Black tiers also leverage OLEDs in one other way: response times. The standard requires a black-to-white response time of 2 frames for OLEDs, as opposed to 8 frames for LCDs. This again reflects the technology: the LED backlights in an LCD unfortunately take some time to ramp up, whereas OLED is virtually instantaneous. So DisplayHDR True Black doesn’t hold back, and certified displays need to be able to ramp up with the kind of quick response rates that the tech is capable of.

Past the specific brightness and ramp-up requirements, the other aspects of DisplayHDR True Black 500 & 400 are identical to DisplayHDR 1000/600. All of these displays need to be able to cover at least 99% of the sRGB color gamut and 90% of the DCI-P3 65 color gamut. And all internal image processing must be done with 10bpc – though 8bpc is allowed for the pixel driver. So DisplayHDR True Black displays won’t necessarily have wider color gamuts or finer steps between colors than DisplayHDR 1000 displays, rather they’ll simply operate with different ranges of luminance requirements.

DisplayHDR 500 – A Little Lighter For Laptops

Finally, tucked in along with the new True Black tiers, VESA is also rolling out DisplayHDR 500. Not to be confused with DisplayHDR 500 True Black, DisplayHDR 500 is a new tier for LCDs. Specifically, it appears to be a compromise tier aimed primarily at laptop vendors. The quality requirements are functionally identical to DisplayHDR 600, however the maximum brightness levels have been reduced to 500 nits for short durations and 320 nits for long durations, down from 600/350 respectively for DisplayHDR 600.

VESA’s announcement notes that this was done particularly to accommodate thin notebooks, where the lower tier is useful for helping to better control thermals in these laptops (a thin screen implies limited thermal mass). Though the VESA notes that like all other DisplayHDR standards, this isn’t limited to one form factor of displays, and that any display – including desktop monitors – could be DisplayHDR 500 certified if an OEM desired.

Source: VESA

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  • a5cent - Friday, January 04, 2019 - link

    ^ someone who gets it!

    DisplayHDR 400 is blatant marketing BS. Any SDR monitor that covers the same gamut will offer pretty much the same experience. Edge-lit monitors with a DisplayHDR 600 certification are probably even worse, as they cost much more while (for most content) not actually delivering more.

    These certifications don't mean these monitor are garbage. They might be great monitors, but they are highly unlikely to deliver anything resembling a HDR experience. Until FALD and MiniLED become much less expensive and more widespread, that is unlikely to change.
    Reply
  • Jorgp2 - Friday, January 04, 2019 - link

    The whole point of HDR is dynamic range, which is why 10 bit is desired Reply
  • Kamus - Thursday, January 03, 2019 - link

    This is kind of dumb... the display should just tell the OS the max peak brightness it's capable off, and have the OS tonemap to that. Reply
  • Billy Tallis - Thursday, January 03, 2019 - link

    That doesn't really address the problem of deciding which monitor to buy, which is what DisplayHDR certifications are supposed to help consumers with. Reply
  • MrCommunistGen - Thursday, January 03, 2019 - link

    I think the most interesting part here is that they've announced an OLED spec. Maybe a bit of wishful thinking, but maybe this is a precursor to actually getting OLED monitors in the PC industry that aren't ultra-niche panels. Reply
  • rsandru - Thursday, January 03, 2019 - link

    That's probably the most important takeaway. :-) Reply
  • mode_13h - Thursday, January 03, 2019 - link

    I've given up on an OLED PC monitor. I'd settle for HDR + adaptive sync at a decent size, resolution, and price. Still looking... Reply
  • doubledeej - Thursday, January 03, 2019 - link

    They've got to solve the burn-in issues with OLED before we'll see monitors meant for computer use. Reply
  • mode_13h - Thursday, January 03, 2019 - link

    This.

    What kind of emissive alternatives are there?
    Reply
  • a5cent - Friday, January 04, 2019 - link

    MicroLED is the only viable alternative on the horizon. MicroLED combines the benefits of TFT and OLED technology (emissive = perfect contrast, no organic degradation or burn in). It's proven to work but so far is too expensive to mass produce.

    We really should stop waiting for OLED to go mainstream in the PC monitor space. It's not going to happen. The flaws/issues are inherent to the organic nature and can't be engineered away. Anything that solves those flaws/issues won't be OLED.
    Reply

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