HDR Color And Luminance

New to our monitor workflow, we've utilized some of CalMAN's recent HDR Analysis workflow additions, again in the SpectraCal suite. As I don't have an HDR test pattern generator currently, we've utilized madTPG for the HDR pattern generator. To note, in SDR mode the monitor reports a "SDR-BT1886" EOTF (gamma) instead of "SDR-sRGB" when in YCbCr mode, but in HDR mode the EOTF is "HDR-ST2084".

Checking back on HDR brightness, we see that the peak brightness is around 1236 nits, reached when a 10% area of the screen was white. So there's definitely room to spare with respect to the 1000 nit minimum requirement.


SpectraCal CalMAN

The HDR gamut coverage matches what we saw with the SDR 'wide gamut' mode, confirming that it covers around 76% BT.2020 and 92% DCI-P3.


SpectraCal CalMAN

Originally in delta ICtCp format, which reportedly describes HDR more accurately, the metrics are in delta E for ease of comparison. The HDR10 media profile targets the BT.2020 space, so it's important to see how well devices designed for the more limited P3 gamut do inside this subset. In that respect the PG27UQ is able to do quite well, with dE's below 3 on color saturation sweeps.


SpectraCal CalMAN

As for chroma subsampling, the 4:2:2 mode kicks into effect when in HDR mode at 120Hz or above. The lack of full horizontal color data can be noticed in certain cases, such as colored text on colored backgrounds where font can become blurry.


4:2:2 (top) and 4:4:4 (bottom) as seen on 12 point font

SDR Color Modes: sRGB and Wide Gamut HDR Gaming Impressions
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  • Flunk - Tuesday, October 2, 2018 - link

    I'd really like one of these, but I can't really justify $2000 because I know that in 6-months to a year competition will arrive that severely undercuts this price.
  • imaheadcase - Tuesday, October 2, 2018 - link

    That's just technology in general. But keep a eye out, around that time this monitor is coming out with a revision that will remove the "gaming" features" but still maintain refresh rate and size.
  • edzieba - Tuesday, October 2, 2018 - link

    The big omission to watch out for is the FALD backlight. Without that, HDR cannot be achieved outside of an OLED panel (and even then OLED cannot yet meet the peak luminance levels). You;re going to see a lot of monitors that are effectively SDR panels with the brightness turned up, and sold as 'HDR'. If you're old enough to remember when HDTV was rolling uout, remember the wave of budget 'HD' TVs that used SD panels but accepted and downsampled HD inputs? Same situation here.
  • Hixbot - Tuesday, October 2, 2018 - link

    Pretty sure edgelit displays can hit the higher gamut by using a quantom dot filter.
  • DanNeely - Tuesday, October 2, 2018 - link

    quantum dots increase the color gamut, HDR is about increasing the luminescence range on screen at any time. Edge lit displays only have a handful of dimming zones at most (no way to get more when your control consists of only 1 configurable value per row/column). You need back lighting where each small chunk of the screen can be controlled independently to get anything approaching a decent result. Per pixel is best, but only doable with OLED or jumbotron size displays. (MicroLED - we can barely make normal LEDs small enough for this scale.) OTOH if costs can be brought down microLED does have the potential to power a FALD backlight with an order of magnitude or more more dimming zones than current models LCD can do; enough to largely make halo effects around bright objects a negligible issue.
  • Lolimaster - Tuesday, October 2, 2018 - link

    There is also miniled that will replace regular led for the backlight.

    Microled = OLED competition
    Miniled up to 50,000zones (cheap "premium phones" will come with 48zones).
  • crimsonson - Tuesday, October 2, 2018 - link

    I think you are exaggerating a bit. HDR is just a transform function. There are several standards that say what the peak luminance should be to considered HDR10 or Dolby Vision etc. But that itself is misleading.

    Define " (and even then OLED cannot yet meet the peak luminance levels)"
    Because OLED can def reach 600+ nits, which is one of the standards for HDR being proposed.
  • edzieba - Tuesday, October 2, 2018 - link

    "HDR is just a transform function"

    Just A transform function? [Laughs in Hybrid Log Gamma],

    Joking aside, HDR is also a set of minimum requirements. Claiming panels that do not even come close to meeting those requirements are also HDR is akin to claiming that 720x468 is HD, because "it's just a resolution". The requirements range far beyond just peak luminance levels, which is why merely slapping a big-ass backlight to a panel and claiming it is 'HDR' is nonsense.
  • crimsonson - Wednesday, October 3, 2018 - link

    "
    Just A transform function? [Laughs in Hybrid Log Gamma],"

    And HLG is again just a standard of how to handle HDR and SDR. It is not required or needed to display HDR images.

    "HDR is also a set of minimum requirements"

    No, there are STANDARDS that attempts to address HDR features across products and in video production. But in itself does not mean violating those standards equate to a non-HDR image. Dolby Vision, for example, supports dynamic metadata. HDR10 does not. Does that make HDR10 NOT HDR?
    Eventually, the market and the industry to congregate behind 1 or 2 SET of standards (since it is not only about 1 number or feature). But we are not there yet. Far from it.

    Since you like referencing these standards, you do know that Vesa has HDR standards as low as 400 and 600 nits right?

    And I think you are conflating wide gamut vs Dynamic Range. FALD is not needed to achieve wide gamut.

    And using HD to illustrate your points exemplifies you don't understand how standards work in broadcast and manufacturing.
  • edzieba - Thursday, October 4, 2018 - link

    "And HLG is again just a standard of how to handle HDR and SDR. It is not required or needed to display HDR images."

    The joke was that there are already at least 3 standards of HDR transfer functions, and some (e.g. Dolby Vision) allow for on the fly modification of the transfer function.

    "And I think you are conflating wide gamut vs Dynamic Range. FALD is not needed to achieve wide gamut."

    Nobody mentioned gamut. High Dynamic Range requires, as the name implies, a high dynamic range. LCD panels cannot achieve that high dynamic range on their own, they need a segmented backlight modulator to do so.
    As much as marketers would want you to believe otherwise, a straight LCD panel with an edge-lit backlight is not going to provide HDR.

    "And using HD to illustrate your points exemplifies you don't understand how standards work in broadcast and manufacturing."

    Remember how "HD ready" was brought in to address exactly the same problem of devices marketing capabilities they did not have? And how it brought complaints about allowing 720p devices to also advertise themselves as "HD Ready"? Is this not analogous to the current situation where HDR is being erroneously applied to panels that cannot achieve it, and how VESA's DisplayHDR has complaints that anything below Display HDR1000 is basically worthless?

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