Prolost Flat to Rec.709 Video LUTS

Do you shoot video with a Canon EOS DSLR or Canon EOS mirrorless (RF or EF-M) camera? Do you primarily shoot footage using a picture style commonly known as Prolost Flat? Do you edit your video in Adobe Premiere Pro? Have you struggled to get your footage to look reasonably good or behave correctly in Premiere’s Lumetri color panel?

I have something for you. It’s free. You’re welcome. Download it here, then read about the what’s, how’s, and why’s below.

Video input LUTS that actually work and are accurate

I’m actually a little amazed nobody has seemed to do this before. Of course, everybody has their own way of color grading Canon EOS video footage, but there is much confusion on the internet about how to deal with the video footage in modern NLE video editing suites for one very simple reason: Canon EOS DSLR video footage does not conform to Rec.709.

Yes, it has the same color primaries as Rec.709, but that is it.

There is nothing else about Canon EOS DSLR video footage that looks even remotely close to Rec.709. If anything, it’s awfully close to Canon LOG believe it or not, assuming of course that you’re using the Prolost Flat picture style.

You see, what is going on is Canon EOS DSLR (including EF-M and newer RF mirrorless) cameras actually record video with an OETF of sRGB. Kind of. Sort of. Actually, not really.

It records video using Canon’s in-camera picture styles. These picture styles are designed to render a pleasing jpeg image if viewed with an sRGB monitor. The reality of the matter is the camera is capturing over 12 stops of dynamic range (on newer Canon cameras) and jamming that into something that looks good in sRGB.

This by itself isn’t so much of an issue, the issue is:

  1. There is more than one picture style
  2. You can edit the picture styles
  3. If you make the Prolost Flat picture style you have a lot more dynamic range than Rec.709 can display.
  4. It’s not Rec.709

So what to do?

This is actually pretty straightforward. Adobe Premiere Pro (and Lumetri by extension) internally are very strict Rec.709 video platforms. They are Rec.709 video through and through, at least as of early 2020. You can’t change it, configure it to something else, or do anything about it. If you want them to work correctly with your video footage, it needs to be Rec.709 video footage.

Plain and Simple.

So, do a little testing, characterize the dynamic range of Prolost Flat and work out what actual RGB video code values map to scene referred linear light, then takes those code values and map them to appropriate Rec.709 values in a tidy little LUT .cube file.

What do you get?

The zip file contains two .cube files. They are both technical input LUTS designed to be used as input LUTS in the Lumetri Color panel in Adobe Premiere Pro. They are named and labeled to make them easy to tell apart.

The first LUT is a full range LUT. I recommend this LUT to be used most of the time because it linearizes the full range of what the camera can capture in Prolost Flat so that the rest of the Lumetri Color controls after it actually work correctly, and you therefore have the most flexibility in dealing with your video footage. This LUT makes Rec.709 video code values all the way up to 120 IRE (because that is what the camera is actually capturing in dynamic range) on the top end and does not dip below 0 IRE on the bottom end. How to actually deal with this much dynamic range during the video color grading process is a subject for another blog post, however, this LUT gives you as much in-camera video capture and post processing flexibility as what is afforded by using Prolost Flat as a picture style. You can expose in-camera however you want, confidently knowing that the Lumetri Color controls will work the way you expect them to once you apply the input LUT.

The second LUT is almost exactly the same as the first LUT, but has one change. It keeps the video code values in the Rec.709 broadcast safe legal range. If you use this LUT, you should take great care to expose correctly in-camera. This LUT introduces a knee in the highlights to roll off the upper highlights and specular highlights so that no matter what you do in-camera, you will never exceed Rec.709 broadcast levels in Lumetri after this LUT is applied. If you’re shooting in a studio with very controlled lighting and you’re not really going to get nutty with the color grade in post processing, this LUT is a very simple and fast way to make Rec.709 compliant footage that looks really good.

Caveats

Using these LUTS may not look very good unless you’re actually looking at your video footage on a Rec.709 display. If you look at it on an sRGB display, it won’t look the same. Again, this is for making in-camera footage Rec.709 compliant so that Adobe Premiere Pro and Lumetri Color will work the way they’re supposed to. You still have to conform your video footage to whatever your output is, be it Youtube, Netflix, Vimeo, or actual network broadcast TV.

These LUTS are standard .cube files, and therefore will probably work just fine with other color grading suites like DaVinci Resolve to conform your Canon EOS video footage into something that those suites can then work with as well. I don’t use those other suites, so do this at your own risk if you do use something other than Adobe Premiere Pro.

These LUTS make the assumption that you’ve actually correctly set your Canon EOS DSLR or Mirrorless (RF or EF-M) camera up with a correct and proper Prolost Flat picture style. While other camera manufacturers (Nikon, Sony, Fuji, Panasonic, etc.) have in-camera neutral picture styles that you can modify in a similar way to Prolost Flat, they are not the same and should not be used with these LUTS. Those cameras should have their own LUTS made for those specific camera picture styles.

Conclusion

If there is enough interest, I can probably make a few posts or videos with how to deal with the post-LUT footage in Lumetri along with some best practices that I’ve come up with over the years.

Enjoy!

Petaluma, CA, USA

Author: Adrian Bacon

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