Author: Adrian Bacon

San Francisco Bay Area Portraits | Headshots | Event Photography | Photo Lab | Bespoke Printing Services | Film Processing

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!

Does The Color Temperature Of Your Light Affect Skin Tones in Photography?

OK, we’re going to get nerdy here. There are many different kinds of artificial lights, and then there is the light from our sun, commonly referred to daylight. If you want to read up on light color temperature, Wikipedia has a great article.

For artificial lights, they generally fall into a couple of different classes: warm, neutral, and cool.

Warm lights are lights that are tungsten, incandescent, candles, etc. Neutral lights are what you generally see in most retail stores, and nowadays usually consists of fluorescent or LED lighting. Neutral light usually sits between 3800K and 5000K. Cool lights are generally any light that has a color temperature above 5000K.

For photography, if you’re shooting ambient light, it’s going to be all over the place. If you’re shooting with continuous “Hot Lights” then it’s generally on the warmer side (2800-3200K), and if you’re shooting with the newer LEDs, the good ones are tunable, but otherwise they’ll be on the cooler side, and if you’re shooting with a speed light or studio strobe, it most definitely will be on the cooler side, usually at least 5500K, but sometimes upwards of 6500K depending on the design of the light’s electronics, quality, and power setting.

This all leads to an interesting question: When shooting people, is there a best color temperature to use that renders more pleasing skin tones? Searching Google leads to lots of articles on how to light for skin tones, but very little in the way of whether to use warmer or cooler color temps for your lighting. With that being said, generally, pros tend to err towards warmer color temperatures (i.e. Tungsten) because it tends to look better. This is why much of our indoor lighting for houses is generally pretty warm.

I thought I would put this to the test and take some pictures using a studio strobe at it’s native color temperature, which is advertised to be ~5600K, and then that same strobe, but gelled with a CTO gel to get the color temperature down to roughly what a tungsten hot light would be, which is ~3200K, then compare the two and see what it looks like. Note: the color temperature is going to vary a little depending on the power level of the strobe, but it should be roughly correct.

So lets start with a standard bare strobe with no color correction:

Here’s the color checker chart:

AB7A5458

So we can see we’re correctly white balanced for the light in our software, now lets see what yours truly looks like under the exact same light with the exact same white balance in software:

AB7A5457

I look like a caucasian guy. If anything, my skin is rendering a bit on the flat or gray side partially because I’m one of those people that has a neutral skin undertone. I am however cursed with a pretty bad complexion, so there are parts of my face that are rendering as blotches of color.

Let’s look at the same light, but gelled to 3200K:

AB7A5459

Again, we can see that we are correctly white balanced in our software. Let’s see what I look like under this same light:

AB7A5455

Hmm… that’s interesting.

Let’s look at the two color checker cards side by side. The one on the left is 5600K the one on the right is 3200K:

color_checker_side_by_side

We can see that even though the the white balance between the two matches, the colors don’t exactly render the same way.

Let’s look at me side by side, again left is 5600K, right is 3200K:

face_side_by_side

Again, very interesting. Keep in mind some of the color you’re seeing on my face is due to my less than ideal complexion, which some people may have, so that’s something to watch out for.

So does the color temperature of your light effect the skin tones in photography? I would say yes. Which one looks better? That’s really a subjective thing more than anything else.

The important thing to take away here is that you should be cognizant of the fact that some people might look better in warmer light and some might look better in cooler light and adjust accordingly.

Till next time.