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Video basics3 min read

LESSON 95

HDR video

More light range, not more pixels.

IN THIS LESSON

  1. What HDR changes
  2. PQ and HLG
  3. The formats on the label
  4. Practice: shooting for HDR

What HDR changes

High-dynamic-range video changes the way a signal describes brightness and colour, so a capable screen can show highlights with more detail and brightness, deeper shadows and stronger colours on a capable screen. It does not add pixels, and it does not make a screen brighter than it is. The older system, now called standard dynamic range or SDR, is still shaped by the limits of cathode-ray tubes and is built around a peak of roughly 100 nits. HDR is usually paired with wide colour gamut, so the two are often switched on together.

PQ and HLG

HDR needs a new transfer curve in place of the old gamma. Perceptual quantizer, or PQ, was developed by Dolby and standardised by SMPTE as ST 2084 in 2014; its scale reaches 10,000 nits and it is not backward compatible with SDR screens. Hybrid log-gamma, HLG, was developed by the BBC and NHK, is royalty-free, and is designed to look acceptable on SDR screens that understand Rec.2020 colour, which makes it suitable for broadcast. Rec.2100 allows either. In short, PQ suits streaming and cinema masters, while HLG suits live broadcast, where one signal must serve both kinds of screen.

The formats on the label

On televisions and streaming services you will meet several names. HDR10 is the most common and is supported by all HDR televisions; it uses PQ. Dolby Vision adds scene-by-scene metadata so the picture can be tuned shot by shot. HDR10 Plus does something similar but is royalty-free. HLG is the broadcast option used by some channels and services such as BBC iPlayer and YouTube. HDR televisions spread in the late 2010s, and by 2024 about 64 percent of smart televisions sold supported HDR.

Practice: shooting for HDR

This is working practice. Record log or RAW at 10 bits or more, because 8-bit footage bands quickly when stretched to HDR. Protect your highlights: HDR shows the sky, lamps and reflections in detail, so clipped areas look flat and obvious. Grade on a real HDR monitor, not a laptop screen, and always make an SDR version too, since many viewers will see that one. Keep faces at a comfortable level rather than pushing everything to the peak. Bright HDR images are tiring when overused, so save the peak for the moments that need it.

Try it today

  1. 01Check whether your camera records 10-bit log or HLG.
  2. 02Film a scene with a bright window and a dark corner.
  3. 03Grade one version for SDR and, if you can, one for HDR.
  4. 04Watch both on a phone or TV that supports HDR.
  5. 05Note which details the HDR version keeps that SDR loses.