How was the RawTherapee Film Simulation Collection created? And thanks!

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Hi everyone.
Especially @patdavid.

I’ve been shooting mostly film (and more recently scanning and inverting it in RT with the film negative module). And it’s only recently that I’ve started playing with the film simulation HaldCLUT module for my “purely” digital shots.

With that said, I’m very interested in the process, the choices and the tweaks that were made to create so-called “film simulations”. Unfortunately the RawPedia article about the module omits this part.

The number of film stocks available in the RawTherapee Film Simulation Collection is impressive. I’d be glad to hear what kind of images were used as a base for a given look. Were you, contributors, working off of already inverted scans? Did it involve colour checkers (CC24, 48 or more)? In your source images, to what degree was the processing subject to interpretation?

Is there a place I should look at to find some documentation that will help assess the “validity” (i.e. how confident are the authors a given film simulation HaldCLUT is as realistic as possible?) of certain looks?

In @AlexandrTantsura’s :thread: The source of film simulations, @afre was saying:

The simulations should match pretty closely. We have lots of talented people who make these cluts, some with actual reference material. The sources should be documented in the source code.

Then, @patdavid :

Portra 400 was likely a combination of multiple other efforts tweaked to something pleasing.

Then @nik concluded:

Pat David’s answer suggests that the Portra emulation is not actually trying to match Portra particularly well, which might explain the OP’s observation.

:person_shrugging:

Threads I’ve read:

Now, apart from the scientific grounds for the previously mentioned collection, I’m also interested in HaldCLUT attempts that were made using this approach: The Peter Principle - Out of Focus: Emulating analog film digitally Part 2 - Emulation process
i.e. take your favourite colour checker, your film stock, shoot it in whatever conditions you want to approximate/replicate on digital, match it to your digital capture and create a new HaldCLUT.

Thanks everyone for reading.

EDIT:
Found these:

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