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HDR black level test: how much shadow detail your screen shows

By TechCompare · Updated · How we check

On an OLED you should see most of the patches against true black. On an LCD the backlight lifts black itself, so the darkest patches blend into a glowing gray. Either way, dim the room first.

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HDR Test

Near black. Turn the room lights down and count how many patches you can tell apart from the black around them.

Run the full screen near black test on TechCompare.

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HDR isn't only about bright highlights. The PQ signal can ask for very dark shades too, down to a few ten-thousandths of a nit. The Near black test shows eight patches from 0.0005 to 5 nits on pure black. How many you can tell apart says a lot about your screen's black level and how it handles shadows.

Topic
HDR near black test
Shadow detail
Test
Near black
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How this is calculated

The patches line up with VESA's black level limits. DisplayHDR True Black allows 0.0005 nits, DisplayHDR 1400 allows 0.02, DisplayHDR 1000 allows 0.05, DisplayHDR 500 and 600 allow 0.1, and DisplayHDR 400 allows 0.4. The last two patches, 1 and 5 nits, are dark grays any screen should show.

An LCD can't turn its backlight off for one pixel. Without local dimming, the whole screen sits at one black level, and patches darker than that level vanish into it. With local dimming, the zones behind the patches may light up, which lifts the black around them and can leave a faint halo.

OLED turns each pixel off for black, so it doesn't have that problem. Its trouble spot is just above black. Some panels crush the darkest shades to black, while others show them unevenly. If the first patches vanish on an OLED, that's black crush, not a black level problem.

Settings and the room change the count too. A shadow or black level setting on the monitor, room light reflecting off the screen and your eyes' adaptation all play a part. Turn the lights down and give your eyes a minute before you count.

Verdict

Use the count to compare settings on the same screen, not one screen with another, since the room and your eyes change it. If you see far fewer patches in HDR than you expect, check the monitor's shadow or black level setting, then try the test in a darker room before you decide.

More HDR Test scenarios

How to test an HDR monitor
Turn HDR on in the right places, then use brightness steps to see where your screen stops getting brighter.
View details
What nits mean for HDR
A nit is one candela per square meter. Here's where SDR white, HDR reference white and the DisplayHDR tiers sit.
View details
HDR looks washed out
Gray blacks and dull colors in HDR mode usually come from settings, not a broken screen. Here's what to check.
View details

Related guides

OLED near black uniformity
Uneven shades just above black.
View guide
Black and white clipping test
The SDR version of this check.
View guide
VA vs OLED
Black levels on the two darkest panel types.
View guide

Frequently asked questions

Why can't I see the darkest patches?
Your screen's black is brighter than they are, so they disappear into it. On an LCD that's the backlight. On an OLED it's usually black crush, where the panel or a setting turns the darkest shades into black.
Does room light change the result?
Yes. Light reflecting off the screen lifts everything dark, so the dimmest patches vanish in a bright room. Test in a dim room first, then in your normal light to see what you'll get day to day.
What black level does DisplayHDR ask for?
With white on screen at the same time, VESA allows 0.4 nits for DisplayHDR 400, 0.1 for 500 and 600, 0.05 for 1000 and 0.02 for 1400. Every True Black tier allows 0.0005 nits.

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