I work for/with/teach pro colorists, so I've been around this type of work for over a decade. What you're trying to do is a standard thing. Take a log-encoded file, and transform that math of the encoding to the math of the sequence and/or display system. Which in the old days 2-4 years ago meant either a LUT or a manual conversion process. Actually, with much experience in doing this with color controls, even in Premiere, you can do it per clip in less time that it takes to find the correct LUT and apply it, then trim the clip to fit the LUT. And anyway, most pro colorists either roll their own conversion LUTs, or use the transforms provided by the programs. Because no LUT can be really built for all "made in the wild" clips you may have. They are built from clips that have had a certain scene contrast and color combined with specific camera settings and even a bit of aesthetic choices by the person building that LUT. So even on LUTs you create for your own clips, you need to apply the LUT to the clip, but then, in color corrections applied before the LUT, you need to adjust exposure and contrast and saturation to fit the clip into what the LUT was built to work with. Or you will get either clipped or crushed data, or shadows not where they're supposed to be, highights in the wrong place, all that type of issue. In Premiere, that means using the Creative tab to apply your log-to-linear conversion LUT, then using the Basic tab to do the trimming for that clip. Log to linear LUTs are really falling out of favor with colorists anyway, as the algorithmic math used in tonemapping in both Premiere and Resolve blows away the limited 'math' of pretty much any LUT. And because of the far better, complex math involved in algorithms, you don't need to trim the clip to fit the LUT. Especially for those without a lot of experience, you will get far better results, faster, and without breaking your pixels, if you use Premiere's tonemapping to do the log to linear work. That's just the basic heavy lifting to get a solid, safe and reliable starting point. Then you either do manual adjustments to taste, or create Lumetri presets of your own with any settings you like that fit your project needs and aesthetic choices. And apply them to entire groups of clips in the project panel bin as a "source" effect. Awesome control, and fast.
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