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Why I NEVER use LUTS When Primaries Grading EVO II 6K Footage

herein2021

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I thought it was time to share another food for thought post and while this does not usually cost money, some people do in fact pay for primaries LUTs so this is another post that could save you money. Similar to the posts on why I never use CPL filters and why I never use ND filters with drone cameras I am just sharing my own personal experiences and workflow after over 10yrs of shooting commercial photography and videography projects. LUTS seem to be another area of mass confusion for people just starting out in the video production world so hopefully this post will help clear some of it up.

BACKGROUND

What is a LUT? A LUT (Lookup Table) transforms color values to specific output values. In more layman's terms, a LUT can very quickly transform your source footage into something more useable especially if you shot in a LOG profile. I am not going to go into the fine details of the differences between 1D LUTS and 3D LUTS, just suffice it to say that 3D LUTS have the ability to provide more granularity over specific color values in the video footage.

I previously mentioned LOG, LOG is a camera shooting profile which initially reduces the dynamic and tonal range of an image to provide additional flexibility in post. The main thing LOG does is reduces the chances of crushing the lows and clipping the highlights which allows you to maximize the dynamic range of the image in post by expanding the lows and the highs to perfectly fit within a chosen color space. Long story short, shooting in LOG provides the maximum color grading flexibility in post and tends to provide an image with the most dynamic range that the camera is capable of producing at its native ISO. Typically the flavor of log is denoted by an extra letter; for example Canon's Log Profiles are CLOG1, CLOG2, and CLOG3 (depending on the LOG curve), Panasonic's LOG profile is called V-LOG for Varicam Log, and so on. For Autel, I typically call it A-LOG for Autel Log.

All of that dense jargon is meant to say that if you want the maximum quality that your EVO II 6K's camera can produce, you should shoot in a LOG profile. Notice that I am very specific with the drone here; I know nothing about the Nano's camera capabilities, LOG profile, or if I would make the same recommendation for the Nano unless I had actually worked with it. Not all LOG profiles are created equal; with my DJI drones I never used their DLOG profile because their LOG curve was terrible and tended to unrecoverably and destructively flatten the image.

MY TEST RESULTS

When I first got the EVO II 6K I did a lot of testing with the available free LUTS then I did my own testing within Davinci Resolve. What I found was that I was able to achieve the look I wanted within a few clicks in Davinci Resolve for the primaries grading without using any LUTs. Notice that I am specific about the fact that I don't use LUTS for primaries grading. Primaries grading is where you make adjustments to the footage to fit within a specific color space. I will skip the additional dense technical jargon for what Rec709 is but suffice it to say it is a color standard that offers the maximum viewing compatibility for everything from cell phones to big screen TVs. Primaries grading is where you adjust the source footage to adhere to your chosen color space. Typically during the primaries grading stage your focus is on expanding the highlights to fit within the color space without clipping and reducing the shadows while preventing them from being crushed.

BENEFITS OF LUTS

  • Speed - the main benefit of using LUTs is speed, if your footage was properly exposed you can quickly achieve a desired look without knowing much if anything about color grading
  • Simplicity - most prosumer and all professional NLEs (Non-Linear Editors) allow you to apply a LUT very easily
  • The Look - lets face it, I highly doubt anyone on this forum is a Hollywood colorist so for most of us (myself included), it can be difficult to achieve a certain look without a LUT. Keep in mind I keep using the word "primaries" LUTs throughout this post, I will get to more on that in a second.

LUT PROBLEMS

  • Cost - High quality LUTs created by professionals typically cost. Sure there's tons of free ones but they are usually created by non-pros which means you will probably not get the most out of your camera with them.
  • Destructive - applying a LUT is a destructive process. What this means is you cannot directly adjust the changes it makes to the footage. All of the color values, tonal ranges, etc. that the LUT chooses to throw away are unrecoverable at a later stage in the color grading process. LUTs can change footage in strange and mysterious ways with no way to correct them other than removing the LUT.
  • One Size Does Not Fit All - The biggest problem with primaries LUTs is that one size does not fit all. If the footage was not perfectly exposed or if the author was not experienced at creating LUTs with maximum compatibility, the destructive properties of using primaries LUTs will become readily apparent.
WHAT I DO

I use Davinci Resolve for all of my post production work to include editing, color grading, sound sweetening, effects, etc. Davinci Resolve is THE gold standard in the colorist world and is becoming THE gold standard for video editing. It has features and capabilities that far exceed anything I will ever need to do. With that said, my primaries color grading workflow is very simple. As I previously stated, I am not a Hollywood colorist, I am not shooting feature length films, nor am I working on the next Hollywood blockbuster; my goals when color grading is to get something commercially useable and visually appealing as quickly as possible. So below is my workflow:

  • Import the footage into DR
  • Drag the footage to the timeline
  • Switch to the color tab and create 3 serial nodes.
  • I disable Node 3 and apply a False Color LUT to the node. The False Color node is what I use whenever there are people in the footage, I use the false color IRE values to ensure skin tones are properly exposed.
  • I use Node 1 and the Wave Form Monitor to adjust the lift, and gain until the desired look is achieved or I have maximized the dynamic range of the footage within the Rec709 color space
  • I use Node 2 to adjust the curves if needed to more finely tune the exposure within the image. I then enable Node 3 and make small adjustments to Node 1 if people and skin tones is the priority for that particular scene. With drones this is less important since drones are typically farther away from people than my other cameras.
  • I also add 1.2 for contrast and between 80 and 100 for saturation. If there is a lot of red or green in the image I tend to use 80 because those colors like to oversaturate. If the drone is high up and far from everything I tend to use 100 and if it is a cloudy day I may even add up to 20 in color boost.
  • On Node 1 I also set the WB by using the sampler to touch something white on the ground if possible.
At this point the Rec709 color grade is done, I copy the grade to all of the other drone clips and make slight adjustments to the highlights and shadows if the sun went behind a cloud or the footage was shot on different days, time of day, etc. All of this sounds like a lot of work, but once you get used to it you can perform the grade within 30s tops.

CREATIVE GRADE

Up until now I focused on primaries grading. The sole purpose of primaries grading is to configure the footage to fit within a chosen color space (i.e. Rec709). Once the footage is there though, you probably want the overall project to have a certain "mood" or "look" that is beyond the clinical Rec709 look. This is where the creative grade comes into play. And this is where I do use a LUT. A creative grade is used to give your entire project a similar look and feel between scenes, cameras, etc. The creative grade really ties everything together especially when using many different cameras.

Good creative grades are created in a way to where they are meant to be applied over a Rec709 or other color space grade. They make the assumption that all of the footage they are applied to already fits within your chosen standard so instead of focusing on maximizing the dynamic range of your LOG footage, their focus is on shifting different parts of the color spectrum to achieve a certain look.

CONCLUSION

It took me awhile to decide to write this post because most people are perfectly happy with just applying a LUT or even a few LUTs over their footage and moving on without any desire to do anything differently. Many people don't even shoot in LOG because LOG must be color graded prior to use. The biggest benefit to LOG is that you can achieve more with it and it is easier to match different cameras when shooting in LOG but yes, it definitely requires more work to color grade.

My hope is some of you find this useful and if you truly want to get the most out of your drone camera you may one day realize that the only way to do so is to do your own primaries grading.

EXAMPLES

Below is just a quick look at my Davinci Resolve setup and a typical color grading node tree for me. In the image below, I have disabled node 1 to show the image with all of the primaries corrections removed and I disabled Node 2 to disable the curves adjustments. Notice the Wave Form monitor shows everything is within the DR of the camera and that I leaned towards the top of the range to provide maximum DR.


Davinci_Resolve_Layout.JPG

In the following image I have enabled my primaries and curves adjustments.

Davinci_Resolve_Layout_w_Adjustments.JPG

BONUS TIP

If you decide to shoot LOG, use the histogram to expose properly. The exposure meter is completely useless for exposing LOG. As long as the histogram does not show clipping, the WFM in Davinci Resolve will not show clipping either. I tend to expose towards the high side of the histogram then crush the lows later in post to add back contrast. I wouldn't quite call my approach ETTR (Exposing To The Right) since I am not using the exposure meter and instead am using the histogram, but it lets me quickly rotate the drone away from the sun without dipping into under exposure. Shooting in Florida, its typically a bright sunny day so exposing a bit to the right for the highlights helps you minimize exposure adjustments as the drone turns and the camera angles change.

IN CASE YOU MISSED IT

Why I Never Shoot Video At 24FPS

Why I Never Use CPL Filters With Drone Cameras

Autel EVO II Pro - User Experience from a DJI User

EXPLORE YOUR WORLD: An Autel EVO II Pro 6K Cinematic Story

Why I ALWAYS use Daylight WB with Drone Cameras
 
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