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Sony Raw Highlight Banding/Posterization Issue

special effects lighting highlights banding

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#1 Hayden Mason

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Posted 21 May 2015 - 08:50 AM

Hello everyone.  

 

I recently shot a music video and have run into a bit of an issue with the highlights. 

 

One of the hero props on this one was a set of floating, glowing orbs a la John Carpenters "Starman".  The characters had them in most scenes. Images attached. 

 

I was shooting on a Sony F5 with the Raw recorder. We also had proxies at XAVC 2k going to SXS cards.  I rated the camera at 1250 most of the time to lessen noise, but when dealing with extreme highlights went to 2000 to have the most headroom. No LUTS were baked in, and I shot S-LOG2

 

Both the proxies and the RAW recordings have this issue. It shows up in Sony RAW Viewer and in Premiere CC. It shows up when looking at the RAWs and the SXS XAVC proxies. 

 

We decided early on to fly an actual LED light source on strings and do our best to hide the wires (which were also powering the orbs)  It turned out great and we were ecstatic on set. Being able to key light with a moving source that was also a prop was amazing. 

 

However, when looking closer at the captured footage we found that the banding and pixelation around the orbs was terrible, especially when pushing the exposure towards the dark end.  Quick movement seems to accentuate the issue. 

 

The odd thing is that the frames themselves seem fine, only when playing back do they look odd.  The paused frames are clean of banding and posterization. 

 

I figured with 16BIT RAW we would be fine.  It was obvious we were clipping the highlights.  We tried to do so whenever possible to avoid too much compositing.  Most modern digital cinema cameras aren't film....but highlight roll of is quite decent nowadays.  What I wasn't expecting was terrible banding and posterization.

 

Here is a clip (prores export, not de-squeezed, Slog) that shows the worst of it. It happens a lot. You have to watch in HD to notice the issue.

 

https://youtu.be/vbKAWkfgCA8

 

Notice the posterization on the orb as it descends and on his face as it crosses around his back. 

 

We had planned to composite a VFX orb over some of the blown white highlights anyways. So, I would imagine that smoothing the banding in post might be an option, but it even shows up on hands and faces that get too close to the clipped highlights, as seen in this clip.  

 

I have no idea how to fix this issue.  Is it something debearing or reincoding may fix or am I just out of luck?  Im no expert, but I assumed the camera would be able to handle some blown highlights.  After all, clipping windows, little hot spots, and clouds can look fine on this camera in my experience.  All of my research pointed to the ability to wrangle down highlights in post.

 

If anyone has any helpful words it would be most appreciated. Im not the most tech savvy at this point in my career, and even if this project is unfortunately hurt by this issue I would love to know why it happened and how to avoid it in the future.  Or if anyone has any pointers towards a fix/workaround.

 

My hope is that is an issue with post processing and not something that the raw recorder or F5 did internally...Like I said, the frames themselves are clear of the issue, it is only when you hit play that the digital garbage appears. 

 

Thanks so much for your time!

 

 

Attached Images

  • Screen Shot 2015-05-20 at 9.18.03 PM.png
  • Screen Shot 2015-05-20 at 9.20.24 PM.png

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#2 Bruce Greene

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Posted 21 May 2015 - 10:50 AM

I think this looks fantastic! I wouldn't be worried.

That said, it may be an issue (though I can't really see it) of log recording. In log fewer bits are used for highlights vs midtones.

Did you see the effect live on the set?
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#3 Bruce Greene

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Posted 21 May 2015 - 10:53 AM

I see you recorded RAW. Try grading and rendering the shot without using LOG space as your master. Does this help?
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#4 Stuart Allman

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Posted 21 May 2015 - 05:55 PM

Hayden,

 

Are you sure this isn't a matter of your NLE preview settings?  Are you using full resolution during playback.  I know in Premiere Pro I can set various resolutions for playback and I usually edit with 50% resolution for screen space reasons.  I set my paused resolution to 100% so I'm not looking at artifacts of the fast scaling algorithm.  Maybe you have your edit setup similarly(?)

 

I imagine the Sony raw viewer might have similar settings, but I've never used it so I can't provide any advice there.

 

Stuart

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#5 Mark Kenfield

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Posted 21 May 2015 - 10:31 PM

It may be the youtube compression, but I'm not seeing any banding. If you are seeing banding though, the first thing to try is adding a bit of randomised noise or film grain to the image before the grade is applied on top, that's fixed every banding issue I've ever had in the past.


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#6 James Martin

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Posted 24 May 2015 - 01:01 PM

I couldn't see any issues in that clip, but YouTube is a git. I think if pausing makes it go away, then it is an artifact being created by your NLE.

 

Out of curiosity, did you shoot Anamorphic?


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