Automating LUT Workflows


By: Jesse Korosi

Over the years, I have been promoting the idea of always sticking to CDL compliance whenever possible; which means having a single “Base LUT” across all media and making your color adjustments shot to shot via CDL. Consequently, I have always tried my best to avoid having a set of LUTs in production that do not have a CDL equivalent.

Why did I care?

CDL values can be placed into an Avid Bin. They can be exported out into an EDL. Many programs like Baselight, Resolve, etc, can extract and re-apply the CDL values from that EDL in just a few simple mouse clicks. Extracting the CDL values for VFX vendors can also be a 1-click endeavor. With this process being automated, everyone will actually use the dailies, or DIT color, and therefor VFX shots will always match back up when dropped into the offline edit.

If applying the color used on set/in your lab requires too many steps, is overly complicated, or time consuming, VFX vendors will simply not use the color and now your offline edits color jumps around, completely distracting you from what you’re supposed to be focusing on: the edit, not the color!

Now, let’s assume we used a whole bunch of LUTs on the front end, instead of CDLs. Anyone down stream in post-production who wants to apply a look will need to:

  • Figure out what the shot is
  • Look in a database
    (Hopefully someone has made/managed one to find that shot!?)
  • Look at the LUT column to see what LUT was used
    (Let’s hope someone actually tracked this?!)
  • Now go and track down who has that LUT, or if you have it already, track it down
  • Figure out if it was an input or output LUT
  • Manually apply it

Now do that for every single shot you are working with…maybe you just received a VFX pull with over 100 shots. Good luck 🙂

Let’s look at it from a VFX review standpoint. When we were doing VFX reviews for “Warcraft,” we would typically get around 20-30 shots with about 5-10 minutes notice that the producers were going to walk into the room for the review. These shots would come in as LogC DPX frames. We then needed to drop these into a timeline and ensure the original dailies color was re-applied. Trying to look to see what LUT went with what shot, referencing some database would have never worked. However by using CDLs, this process was automated.

Aside from the VFX angle, we have had more and more colorists start asking that these color values also track through. Some as a high resolution reference, rather than relying on the QT that could have been altered by editorial. Some would ask to actually use it as a starting point. I know many colorists reading this are probably cringing at the idea of it being a starting point, but it does happen. The first time we did this was back on “Pacific Rim” and it has since happened on a large Arri65 feature (“Alpha”) we did and happens on the odd TV show where a final colorist is not given much time in their bay. Going full circle, do you think the colorist is going to sit there trying to figure out what LUT goes with what shot to re-apply the on-set looks? Hell no. On the other hand, with CDLs (or BLGs) this is very simple and just a few clicks.

Fast-forward to 2017 and I think I finally have a solution to this LUT problem.

We at Sim have a database we manage for every client that houses all metadata and technical information related to any job we’re doing dailies on. This is an aggregation of data collected from anyone taking digital notes on set, alongside our lab.

One of many new exciting tools we have added to our database is the ability to upload your VFX pull EDL and be prompted to download a zipped folder. Within this folder, each event from the EDL is now its own folder, named after the VFX Shot Name. Within each of these VFX Shot folders, you will have the specific LUT and or CDLs used, which have also been re-named to match the VFX shot name. Also, within each individual shots folder will be a CSV extraction for that single event, with all Metadata we have aggregated across production. With this kind of organization and automation, all guess work for what look goes with which shot, has been removed!

This tool is now available for both our internal crew, as well as any client that has a VFX Pull EDL!

Director of Workflow