HDR VIDEO PART 4: SHOOTING FOR HDR

[jacob.schwarz]

Part 4 of our on going blog series on HDR is up.

http://www.mysterybox.us/blog/2016/10/20/hdr-video-part-4-shooting-for-hdr


Excerpts:

It’s important to realize that, in general, all footage is better in HDR, regardless of its age or how it was filmed. That being said, there are things you can do while filming to best prepare for an HDR finish.


If you’re using a prosumer or entry level professional camera, taking a few preparatory steps to set up how you’ll actually be capturing the image can mean the difference between getting footage that can be used in HDR mastering, vs. footage that can’t.


In summary, when choosing your kit for HDR, consider:


16 bpc > 14 bpc > 12 bpc > 10 bpc > 8 bpc: 10 bpc should be your minimum spec.
RAW > LOG > Linear > Gamma 2.4: avoid baking in your gamma at all costs!
Camera Native / BT.2020 > DCI-P3 > Rec. 709 color primaries
RAW > Compressed RAW > Intraframe compression (ProRes, DNxHR, AVC/HEVC Intra) > Interframe compressed (AVC/H.264, HEVC).




As for the technique, consider the following:


- The goal for HDR shooting is to expose your whites to eliminating clipping the RAW data when possible, and minimizing it when it’s not. Stop down or use ND: protect your highlights and avoid clipping like the plague


- If you’re planning on using a PQ/SMPTE ST2084 HDR mastery workflow, you’ll need to assume that most of your deep darks are in fact visible, beyond what you’d normally consider available.


- When you shoot for HDR, you can’t assume that every consumer display will be HDR. So you need to consider that how the darks and lights will play in both HDR and SDR.


- The overall dynamic range of the scene needs to be planned in a way that the super bright / HDR elements are restricted to a small portion of the overall frame, so as to not push up the frame average light level.


- Because of the expanded darkness range of HDR, you can design much more ‘dark and moody’ lighting setups than you normally would for standard film or video exhibition.






Follow us over to our latest blog post for more details, at http://www.mysterybox.us/blog/2016/10/20/hdr-video-part-4-shooting-for-hdr

 

[Stacey Spears]

- Because of the expanded darkness range of HDR, you can design much more ‘dark and moody’ lighting setups than you normally would for standard film or video exhibition.

There is a video, from NAB, where a film maker was talking about how he did not like HDR because it showed all the shadow detail. He simply did not understand that you, as the film maker, can show as little or as much shadow detail as you like. In fact, you can make your content look like SDR inside of HDR if you so please.

I would like to see someone use HDR like Coraline used 3D. Maybe in the real world everything looks like SDR. Then when you are in the fantasy world everything looks like HDR. Simple idea.

Someone could take one of the debates and grade one candidate in SDR and the other in HDR to have a little fun.

 

[Michael Tiemann]

[...]
16 bpc > 14 bpc > 12 bpc > 10 bpc > 8 bpc: 10 bpc should be your minimum spec.
RAW > LOG > Linear > Gamma 2.4: avoid baking in your gamma at all costs![...]

Umm...RAW is Linear: every RAW pixel value is a linear light value. Your statement RAW > LOG > Linear > Gamma 2.4 is correct when you start clipping the precision to smaller numbers of bits per pixel/color. 8-bit Linear definitely sucks much more than 8-bit LOG, being very badly behaved as values go toward the last few stops of black. But 16-bit Linear is about all the precision there is, and so is no worse than 16-bit LOG. I also agree that 10-bit values should be the minimum spec, which is why I think it is unfortunate that RCX only supports 8-bit precision when displaying video on a GUI monitor (even if that monitor has 10-bit support in the OS).

 

[Samuel Bilodeau]

Umm...RAW is Linear: every RAW pixel value is a linear light value. Your statement RAW > LOG > Linear > Gamma 2.4 is correct when you start clipping the precision to smaller numbers of bits per pixel/color. 8-bit Linear definitely sucks much more than 8-bit LOG, being very badly behaved as values go toward the last few stops of black. But 16-bit Linear is about all the precision there is, and so is no worse than 16-bit LOG. I also agree that 10-bit values should be the minimum spec, which is why I think it is unfortunate that RCX only supports 8-bit precision when displaying video on a GUI monitor (even if that monitor has 10-bit support in the OS).

You're right, in an apples to apples, uncompressed RGB situation, 16 bit log is as good as 16 bit linear. It's a little poorly phrased on my part. My point is actually that RAW is superior to any of the video formats, typically because RAW formats preserve the full range of the sensor bit depth, which is often greater than the bit depths available for recording, say, a 14 or 16 bit sensor with values translated into 10 bit ProRes 422. When you deal with that transformation, LOG ends up with the advantage because it more evenly distributes the linear RAW values (at a higher bit precision) more evenly into the 10 bit range, whereas linear ends up weighted with values to the darks and hence loses dynamic range precisions in the lows while wasting bits in the highs.

So yes, if the recorded bit depth is the same as the sensor bit depth, RAW = Linear > LOG. But when, as is most often the case, a greater precision sensor is scaled into a lower precision video format, RAW > LOG > Linear.

 

[Samuel Bilodeau]

There is a video, from NAB, where a film maker was talking about how he did not like HDR because it showed all the shadow detail. He simply did not understand that you, as the film maker, can show as little or as much shadow detail as you like. In fact, you can make your content look like SDR inside of HDR if you so please.

To me that complaint is like a filmmaker saying "I don't like DCI-P3 space, because it has too many colors. I don't want to use that many colors". The point of any new tool or standard is that it opens possibilities - do with it exactly what you want!

I would like to see someone use HDR like Coraline used 3D. Maybe in the real world everything looks like SDR. Then when you are in the fantasy world everything looks like HDR. Simple idea.

That's a really interesting idea, and I wish there was a practical way of doing it sometime soon. But unlike Coraline that benefited from the use of anaglyph 3D in home distribution to non-3DTVs, there's no good way of making that effect really pop for SDR distribution :-(

 

[Hugues Dagallier]

To me that complaint is like a filmmaker saying "I don't like DCI-P3 space, because it has too many colors. I don't want to use that many colors". The point of any new tool or standard is that it opens possibilities - do with it exactly what you want!

[/COLOR]

Yep. HDR opens new possibilites, that's all. We all really should be very excited about it.