Here’s an update:
Over in another thread I realized that these 64x64x64 LUTs I’ve been building were massively over-conditioned. Scaling them down to 16x16x16 not only cut down processing time, but also produces smoother results.
More importantly, experimenting with Wilecoyote’s code made me realize I had one broken file in my training set. That dark shadow you can see in my previous test images was caused by that. My bad. This has been fixed.
Also, I removed all the almost-white and almost-black training images from my exposure series, as they are not doing the LUT any good, but take a lot of computation time.
Here’s a current set of LUTs that works quite well!
Fuji LUTs.zip (57.1 KB)
What I don’t yet understand is why these LUTs don’t reproduce the original JPEG colors better. It seems to have something to do with the way filmic processes colors. Or maybe my color averaging code is not working so well on account of the sRGB tone curve or something. At any rate, the LUTs in their current state do recreate the Fuji Film Simulation character pretty well, but they don’t match the colors exactly. I wish I knew why.