Adding highlight fix to all shots in a project

Hello,

Is it a good idea to add the highlight fix to all shots in a timeline. The implementation in resolve requires it to be added in the media pool, and takes too long to do it shot by shot. And any implementation doing it shot by shot would take too long. Identifying problem clips, applying the correction, maybe you miss some problem clips… etc. So, what is the harm in doing a blanket fix to all clips in a timeline. I know it’s warping some colours eg blues very slightly, but I don’t see that being a huge problem. Particularly for content which has a lot of coloured Practicals.

It would be great to hear any views / experience on this. Is there a problem with this approach?

Thanks
Colin

Hi Colin,

In my opinion, if done early on before beginning with color grading, applying the fix to an entire project would have very minimal effect. It can shift all colors ever so slightly, but it is definitely (and intentionally) most noticeable in blues. Since minor adjustments are likely going to be made anyway, any undesirable effects can be adjusted back out while gaining the benefit of circumventing very noticeable clipping artifacts. Think of it as a subtle “show LUT” that you can then apply further adjustment to.

This also presumes that the DP or director haven’t already fallen 100% in love with exactly how they captured it on-set. So it depends on the type of project and what the priorities are - avoiding artifacts? or getting exactly what was captured? (even though it’s likely to be color-corrected somewhat anyway)

That being said, it’s easy for me to say this since I haven’t personally needed to use the fix on actual productions. I usually just provide it for one or two problem shots. So others who have more practical experience implementing it might have other experiences and opinions.

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Thanks Scott. This is exactly how I see it too. Most shows won’t require this, but depending on practicals, lighting and sets, it’s something That is sometimes necessary. / useful.

Thanks
Colin

Hi Colin,

I work in the games industry and we have much less control over what happens in each shot due to player agency than you do in the movie industry and, so far, the highlight fix has been a life saver for us. We actually blend it at a 60% ratio with the non-corrected image (60% corrected, 40% original) and we apply an inverse highlight fix right before converting to display primaries. This inverse highlight fix is blended at a 60% ratio with the highlight fixed image just like we did at the previous step. This is done to maintain white point and I have Brian Karis to thank for the idea. Thanks Brian.

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Thanks for the info. I’m not a gamer, and surprised that Aces workflows are being used in the games industry. I hadn’t given it any thought. But it makes sense. That is awesome!

Hi @jmgilbert,

It is something I reported to Brian and Epic because it is highly-problematic: there is no practical way to replicate that in the current ACES block diagram. There is no place for it where it can be inserted, i.e. no output/display-referred LMT.

Cheers,

Thomas

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Hi @colin,

What about using the new gamut compression operator? It has the advantage of being very conservative and will never touch any colour inside the ColorChecker Classic gamut?

You will find various implementations here: GitHub - colour-science/aces-vwg-gamut-mapping-2020: ACES - Virtual Working Group - Gamut Mapping - 2020

Cheers,

Thomas

Thanks for bringing this to my attention. I’ll check this out.

Hi @Thomas_Mansencal ,

I know the inverse highlight fix is problematic from a pipeline point of view. It basically means that we are maintaining a whole custom set of output transforms with custom features. This is not as bad as it sounds for us since we have control of the full pipeline, we’re not relying on external technology vendors and we have validation processes for contractor work. However, we are looking to get rid of this specific thingy in our implementation. Maybe the gamut mapper from ACES 1.3 will help. I will evaluate it soon. Whether its conservativeness is a virtue or not, we shall see.

Yours,
Jean-Michel

Hi!
If you’re talking about built-in Resolve LMT Neon Suppression, you can (and usually should) select all the clips you need and then just drag and drop LMT Neon Suppression from LUTs panel to one of the selected clips. This will apply LMT Neon Suppression to all the clips at a clip logical level, after IDT and before all the nodes. So it will be applied to AP0 Linear as it should.

But LMT Neon Suppression also adds some teal-orange look. If you need to preserve most of the colors, you probably should use gamut compress DCTL. But at this moment it only works with AP1 ACEScct, so it can’t be applied the same way.

And you still typically want to do it before any color correction. Because some operations like saturation will make it impossible to undo negative values (I can be wrong here, so I hope someone will correct me here).

I was wrong. It will only apply it to just one clip. To apply it to all selected clips at once, you should select the clips and right-click to select the DCTL/LMT/LUT.