OpenEXR Color Management Question

Might be a bit of a rookie question here–– Looking for some more insight into the most efficient method for maintaining color accuracy when importing OpenEXR files…

I need to convert to ProRes4444 for a client.

I noticed, by default, Flame is tagging the color space as ‘unknown’, however, it seems to be applying some sort of LUT that is really saturating color, no matter which color space setting I choose upon import…

The most accurate fix I have found so far has been to go into color management and throw on a view transform with ‘Linear (sRGB gamma).’ This seems to get it into the ballpark.

Working in 2021.1

Any insight/suggestions appreciated!

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And what colorspace are the EXRs?

I was told they were rec709.
Color space says “unknown” when the clip is highlighted in the Media tab before import.

I have tried tagging the clips as rec709 prior to import and that doesn’t seem to do anything. The clip preview just shows a very saturated image that is nowhere near the color when a single frame is previewed in Finder.

I have reached back out to the client to confirm color space, still awaiting a reply.

The clip’s colorspace AKA “Input CS: Unknown” is listed in the metadata in the media hub before import is Unknown most likely because you have the Tagged Color Space on the bottom of the Import module set to Unknown.

In other words, the Metadata Input Colorspace, Input CS, is a result of what you’ve tagged it. Its the effect, not the cause.

Unknown will not apply any colour LUT. You seem to be getting a better result when you tag it as Linear (sRGB gamma).

With the footage tagged as unknown it appears over saturated. Have you seen this footage in any other preview or is it so obvious that it is wrong? Is it overly saturated and does it also appear to have high contrast levels? Is it dark?

It is common for an EXR file to contain linear footage but it isn’t guaranteed. Can you preview the file on you computer outside of Flame? What does it look like?

There are a lot of assumptions but without a solid reference to confirm that it is very wrong you can only guess.

Seems as if it isn’t Rec.709 so you are clutching around to try and guess. The most obvious start would be that it is linear but that is only half the solution. You want to know the primaries.
Again, most likely this is sRGB/Rec.709 primaries in a linear file. This would be why tagging Linear (sRGB gamma) looks better.

If you don’t want to make a mistake I would screengrab the result, when tagged as rec,709, and go back to the source and ask the question again.


Or if you feel like sending them an example of your best guess.

Lets assume this EXR footage is Linear Rec.709

I would tag the footage as scene-linear 709/sRGB

and then output a ProRes4444 (12-bit) making sure you use LUT in the export window and select ViewTransform and hit Edit.

By saying it was Rec.709 we can just apply a 2.4 gamma curve to the EXR footage using these settings:


Some applications linearize when exporting as exr by default.
So if grading was for broadcast it is supposed to be Rec709/BT.1886 (gamma 2.4) but was exported as scene-linear sRGB/Rec709 when using exrs.
So you only need to gamma transform back to gamma 2.4.

But I wonder why someone would use EXR for a final grade? EXR is supposed to store linear data and can introduce artifacts when there is any other transfer function.
DPX seems to be the more elegant way of storing integer data. And consumes less disk space.

If there’s a special color workflow where you need to color manage the exrs, you need a detail information of the embedded color space from the colorist. Then you can tag those as supposed and color manage them to desired destination color space. But ensure, that you don’t introduce illegal values.

I can think of, that those exrs live in ACES and therefore its an ACES workflow.
That would explain the over saturated colors because of that extremely large gamut.
If so: you can generate any destination color space out of it by yourself using color management in viewing transform mode and choosing the correct aces transform (like ACES 1.0 SDR- video, which converts your aces Footage to a nicely Rec709 gamut and a 2.4 gamma without illegal color values).

FYI: Flame’s Unknown is exactly the same as tagging it as Rec709 video. Therefore Log footage is shown low contrast and linear footage is shown high contrast.
Every software needs to assume some color space to show it somehow on a display. Flames legacy color space is just Rec709.


10 posts were split to a new topic: Compression and Colorspace for EXR and DPX

Keep us posted @nick_devivo with what the client says…let’s be sure to keep this thread about @nick_devivo 's particular situation.

I’m loving the dialogue, please let me know if it makes sense to split some of this into a different topic so we can ensure everyone has the space they need to do their thing.


Thanks for the reply and the screen grabs. Very helpful. Tagging as Scene Linear rec709/sRBG seems to be fixing this issue. And yes, I am able to view the individual frames in Finder preview and see that they clearly look wrong when imported into Flame. They are very dark with high contrast levels.

@ChrisKasten Appreciate your reply as well. The EXR files I received are actually not final grades/renders. They are WIPs for a CG animation.

This was a one off from a client who needed some EXR clips converted to QT for a reel of some sorts. A good exercise in color management nonetheless. Appreciate the replies and information! :slight_smile:


I wouldn’t mind a split–I’ve got a searingly hot take about image compression. Haha.


I wouldn’t mind taking this discussion to another room :slight_smile:

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Glad you found a solve @nick_devivo .

Okay, please see this thread of the tangential conversation…