AE renders EXRs darker?

[Steve Bentley]

15.11 is where the legacy QT codecs met their maker. I wonder if, with the remaining but still long-in-the-tooth QT codecs, AE is forced to emulate ProRes in 10 or 12 bits, but from a 32 bit universe. And as such, can’t quite get the conversion LUT just right.
I don’t remember if ProRes was 10 and 12 bit linear or Log. The latter would complexify that conversion exponentially.

[Andrew Somers]

AE is forced to emulate ProRes in 10 or 12 bits, but from a 32 bit universe. And as such, can’t quite get the conversion LUT just right.
I don’t remember if ProRes was 10 and 12 bit linear or Log. The latter would complexify that conversion exponentially.

Hi Steve,

Most forms of ProRes are either 8 or 10 bits, typically with a video gamma, or sometimes LOG*, but never linear**. ProRes 4444 is 12 bit.

For instance ProRes as it comes out of an Arri Alexa is typically LOG-C, which is a slightly different curve than Cineon LOG, but still “more log than gamma.” ProRes *can* be encoded with any curve you like***, some flavor of log or some flavor of gamma encoding. The transfer curve is a function of the color profile or LUT used when outputting, not the codec itself.

I almost always work in 32 bit linear (gamma 1.0) space inside after effects. Some of the issues that can come up working in linear in AE are partly due to faulty color profiles at various points in the pipeline, including the monitor. If you are working in linear, it is critical to have your monitor both properly calibrated AND PROFILED, so that AE can use your calibrated monitor profile to correctly display images using “View > Use Display Color Management”.

I’m not sure what you meant by “emulate” ProRes — you mean convert from a linear (no gamma) to a gamma encoded form? AE does not use “LUTs” for color management, it is based around ICC profiles****. For color management to work, everything has to be profiled. The issue has nothing at all to do about bit depths — if we were only converting between 10 or 12 bit integer and 32 bit float, the math is trivial. The issue is converting from a flat transfer curve in linear space, to a non-linear space such as video which has a gamma curve, or a film intermediate which typically has a log transfer curve. And here we rely on the profiles.

If you don’t have an accurate monitor profile, what you see inside After Effects working in linearized mode may end up looking very different on output. When outputting from the linear (no gamma curve) environment to video, which has a gamma curve, the image needs to be transformed. In AE that transformation usually happens with an ICC profile.

But I’ve found that those transformations in the output module may come with issues, some are due to how AE handles the linear environment, and some are due to problems with the ICC profiles themselves. For instance in Adobe’s version of the Rec709 profile, the gamma curve is wrong, and no different than the sRGB profile (a simple 0.45 for 2.2 display curve). See this article on Rec709 profiles.

As I mentioned in the previous post, I now avoid using the color management in the output module, and instead set the output to “Preserve RGB” and use an adjustment layer for color conversions. This is of course the required workflow when using 3D LUTs on output, but I find it useful for all outputs instead of relying on CMM. I discuss the reasons in depth in this article.

—
* Footnote 1: the reason “LOG” is around is because a film negative density happens to be logarithmic in nature. When Kodak developed Cineon, they were scanning film negative straight into a digital form, and so that digital representation is log due to the fact that it is a scan of negative film densities, which are log. Gamma curves date back to CRT type television systems, and survive today because perceptually we see greater detail in darker areas of an image, and gamma encoding provides greater luminance resolution (more data) in dark areas.

** Footnote 2: “video” such as Rec709 is gamma encoded, so it is not linear. Linear means a gamma of 1.0 which is a straight line (linear is also the nature of light in the real world). Most video is encoded with a gamma curve close to 0.45, which unwinds into linear “light” when displayed with a monitor at a gamma around 2.2 to 2.4. So essentially, there is LOG, LIN, and VID. I discuss the point in more detail here:
https://www.generaltitles.com/helpfiles/13-q-a-blog/colorspaces-and-file-types/14-red-and-after-effects

And Stu Maschwitz goes into even greater detail here:
https://prolost.com/blog/2009/9/30/passing-the-linear-torch.html

*** Footnote 3: Linear (gamma 1.0) will not fit well into an integer storage format, and needs to be stored in a floating point format such as EXR. Integer formats such as ProRes, JPEG, etc. need the image to be encoded with a curve in order to fit a useful dynamic range into the container.

**** Footnote 4: While you can use 3D LUTs in After Effects with a LUT plugin such as OpencolorIO, that is not part of the “color management” system. The color management uses ICC profiles which are a little different in form and purpose. Some ICC profiles may contain LUTs, such as those intended for output. But the idea behind ICC Color Management is that everything gets converted to a neutral space such as CIE L*a*b*, and then converted to some other working or destination space. 3D LUTs as used in the film industry map directly from one color space to another, frequently to emulate a particular device or output type, e.g. to make a digital projector look like a film release print.

Andrew Somers
VFX & Title Supervisor
https://GeneralTitles.com

[Sergi Esgleas]

Hello Zak,

I have the exact same problem as you. I work in motion graphics and if I export my composition in Apple Pro Res or Lossless from AE, the result is “darker” than the original. The same composition exported in Apple Pro Res in AME looks exactly the same as the original. Even without working with video material, but only with animations generated inside the program. I can’t seem to understand why 2 programs of the same company give different results.
Would be great to find an easy solution to export material in AE without the gamma shift. I’ve read lots of posts that are quite confusing to me.
Thanks!

[Zak Margolis]

Hello Sergi,

Which version of AE are you using? Adobe logged the issue as a bug and has since corrected it. The version I was having issues with is 15.1.1. Adobe corrected the problem in version 15.1.2. And if you go back to AE 14, there isn’t an issue at all. I hope that solves it for you!

Good luck,
zak

z.

[Sergi Esgleas]

Hello,

I’m using version 15.1.2 (Build 69). The only way I don’t experience the problem is working with Rec. 709 Gamma 2.4 color settings instead of sRGBIEC61966 or None in the project settings. Or, as I said, rendering the compisition in AME.
Still confused though.
Thanks,

Sergi

[Sergi Esgleas]

Hello,

I’m using version 15.1.2 (Build 69). The only way I don’t experience the problem is working with Rec. 709 Gamma 2.4 color settings instead of sRGBIEC61966 or None in the project settings. Or, as I said, rendering the compisition in AME.
Still confused though.
Thanks,

sergi
Here’s an screen capture working with sRGBIEC61966

[Zak Margolis]

Ah! Sounds like you could be having color space issues. Being no master of understanding the intricacies of AE color space, I’m afraid I won’t be of much help solving this one. You are in the right place however. There are literally dozens of threads here that talk about color profiles, linear workspace, and their relationship to different formats, etc.

If you decide to start a new thread, you’ll need to include a lot more information about your system and your set up.
What computer are you using? What kind of footage are you working with and where did it come from? And what is the intended final format of your project (is it for broadcast, youtube, etc)?

Sorry I couldn’t be of more help.
Good luck!
z.

z.

[Sergi Esgleas]

Thank you Zak. I understand everything is much more complicated than it seems. Thank you again.

[Jeffrey Knapp]

Hi, I am having a related problem. I am working with footage, plate I am compositing a 3D animation on to, that was shot on a RED digital cinema camera. It has a custom LUT that came with it that the DP supplied.

I exported the footage out to 12-bit half float OpenEXR files.

I imported those files into AE.

The colors came in looking VERY washed out compared to the reference QT file the production supplied me.

Using an “Adjustment Layer,” I applied the LUT supplied to me from the DP.

That brought the colors somewhat closer but not all the way there, they were still more washed out than the reference QT file.

I matched the color and shadow densities of my 3D rendered animation to match the background plate, the theory being that I would pass that on to the colorist at the DI house anyway.

I rendered it out directly from AE and, womp! The blacks were absolutely crushed and there were no bright areas at all. It looked like somebody just turned down the black levels to the point where 50% of the pixels were pushed into black and the rest was just dark and dingy. It didn’t matter if I rendered to QuickTime, OpenEXR, or any other file type or codec.

I’ve done a lot of compositing in my days of just five or so years ago but, this is my first rodeo with digital cinema files such as RED raw files and my first time working with 32-bit color depth footage. I’ve been looking all over the place for help but, just have not found anybody who can (or is willing) to talk me through this color management process.

If anybody here can help me out, I will owe you a big favor in return.

Thanks.

 

—jk—

 

[Chris Wright]

the ref QT. how is it being viewed? if directly from quicktime player, it displays items as gamma 1.96. and I don’t know the workflow of your EXR’s but they are normally linear. did you burn the custom lut into the EXR? You should be uses an ACES workflow in after effects or at the very least, a guide layer. see https://www.youtube.com/watch?v=dHY5rMnBUz8