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Nick2049
Inspiring
May 12, 2021
Question

Colour/Gamma Shift Bug

  • May 12, 2021
  • 3 replies
  • 11448 views

I have discovered that when exporting from AE to ME using H.264 my final output colours/gamma doesnt match my AE viewport.

 

However, if I export to DNxHD directly from AE then the colours match. What's strange is that if I then take this DNxHD and convert it (with the exact same settings) using ME, it also correctly matches!

 

So why the shift when going straight to ME from AE?

 

Results attached

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3 replies

R Neil Haugen
R Neil Haugen
Legend
May 19, 2021

"Don't overthink" is something my colorist buds are always telling their clients. Set up correctly and get to work, essentially.

 

So when it works, work. Confusing as it all is. I've been through I really don't know how many hours of presentations and discussions on CM. Done it on my own machines hours at a time for years. And it's still freaking a mess.

 

Neil

Everyone's mileage always varies ...
N
Nick2049Author
Inspiring
May 19, 2021
But this is what I am trying to do,
I am trying to set it up correctly, but which method is correct? The results are so varied and this wasn’t even an issue in previous versions.

Why does ‘no working space’ respect sRGB and seemingly automatically accurately convert this to Rec709 when sent to ME, but when specifying a working space (either sRGB or Rec709) it does not!?

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R Neil Haugen
R Neil Haugen
Legend
May 21, 2021

Hi Neil,

When AE is set to no working space, my 'assume working gamma:' is set to 2.4 REC709.

I beleive sRGB is 2.2? So this makes sense why there is a shift, but I don't understand why it is happening here, this doesnt add up..

Take a look at the attached, as you can see, no working space with assume 2.4, results in an H.264 that matches my original source content in PS. Great, this is what I want, but why is this happening? If it is assuming 2.4 then why dont I see the gamma shift in my AE viewport? and also even if it is displaying correctly as sRGB 2.2, why doesnt the shift occur when it ends up as REC709 2.4 in ME?

 

What do you make of this?

Cheers


As little as possible ... and I'm not being sarcastic or anything. Much of the interactions in CM don't seem to make sense. You can sit down with an engineer and get an explanation that seems to "handle" something, walk away ... and 20 minutes later have trouble remembering which particular variuos rabbit holes were used to patch an answer together.

 

So what I've been through with so many colorists ... and on the Slack channels and online forums I'm on every day, this is always a current discussion ... the basic answer always gets back to reality.

 

"This is the basic standards. This is how to test if your system is working correctly. Once you have that, no matter what the logic of the settings seems to imply, just get back to work."

 

And this same discussion will happen no matter the apps and the gear. From PrPro through Resolve, Avid, Baselight, Nuke, Ae, Fusion, whatever. Macs/PCs ... everything.

 

And how people need to set similar gear to get correct results can seem rather puzzling. But again, once you can verify the results, well ... there's work to be done.

 

Do I like that answer? Hades no. I like nice, neat tidy solutions. That's where an autistic brain that lives totally by anlysis/synthesis wants to be all the time. Nice, neat, tidy solutions. Which has some of my buds simply roll their eyes when we're together at NAB or MAX.

 

As I was told a while back by a guy pretty much an amazing expert in all this  ... "Ain't happening in this lifetime, bro ... get a Life ... "

 

Neil

Everyone's mileage always varies ...
R Neil Haugen
R Neil Haugen
Legend
May 12, 2021

In Ae, set the project settiungs Color tab to depth of 32 bit float, and the working space to HD TV Rec.709.

 

That should take care of things.

 

Occasionally, people do need to turn off the linearize color spaces option.

 

Neil

Everyone's mileage always varies ...
N
Nick2049Author
Inspiring
May 12, 2021
Hi Neil

Not really sure why I would need to do this.
My working space is 8bit sRGB and my delivery is 8bit sRGB. Also my display is sRGB.

Why is it that first exporting to directly from AE to DNxHD and then converting to H264 using ME seems to respect the colour space. But exporting to ME from AE does not and the shift occurs?

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R Neil Haugen
R Neil Haugen
Legend
May 12, 2021

Because that sets the ciomplete and proper Rec.709 color management up. Which is what you need.

 

Neil

Everyone's mileage always varies ...
R Neil Haugen
R Neil Haugen
Legend
May 12, 2021

What are the complete color management settings you're using in Ae?

 

And what in Me?

 

Neil

Everyone's mileage always varies ...
N
Nick2049Author
Inspiring
May 12, 2021

Hi Neil,

Sorry, I did intend on including those. Here you go:

 

AE: 8 bpc, sRGB, colour management on

 

I don't see any setting in ME, it's just the default H.264 set to same as source. I tried a preset like Vimeo 1080p but this resulted in the same issue.

 

Thanks,

Nick

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