How Should Scopes Appear in HDR PQ?

Concerning an often asked question regarding the appearance of HDR scopes in your NLE, one significant difference is that in SDR, the signal can ordinarily fill out the scopes, say, from 0-1023, while in HDR PQ, the bulk of the signal will usually be bunched up toward the bottom end of the waveform, from 0-200 nits or so, with only small excursions for specular highlights. So what ends up happening is that even if we set, say, 1000 nits as our peak brightness, we might actually only see occasional peaks at 400 or 600 nits and nothing greater than that, depending of course on the project and the subject matter.

The reason for this is that the average picture level (APL) of SDR and HDR should be similar (in fact, HDR not infrequently actually ends up being lower), and generally speaking, everything above 203 nits (diffuse white) is for specular highlights. So while our signal may very well appear identical when switching between 10-bit, 12-bit and HDR PQ in the waveform settings on the Color Page, if instead we were to switch the project settings themselves from HDR to SDR on the Color Management Page, we’d notice that our waveforms look quite different indeed – stretching out to fill the 10-bit scope while shrinking back down to below 100-200 nits in the HDR PQ one.

4 thoughts on “How Should Scopes Appear in HDR PQ?

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  1. Can you explain the scopes view on Ninja V when shooting RAW ? I find it starts from below 0 (!) and goes off the top of the scale too (!) – so rather useless I feel.

  2. Jon, when working in HDR colour space viewing the Vectorscope. It’s impossible to push beyond the 75% targets, but in SDR you can push to 100% targets. I can’t figure out why?

    1. I imagine for the same reason that the mass of the HDR signal occupies around 100 nits or so on the waveform monitor – only the brightest, most highly saturated colors would ever reach beyond 75%. The PQ curve goes to 10,000 nits, whereas HDR10 maxes out at 1,000. Most are also restricting the color space to the considerably smaller P3 gamut.

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