Bad quality LUTs

[Christoffer Glans]

I've been trying to simplify a workflow for fast Premiere projects that needs a grade but without being locked into that grade. So I basically grade a reference image and do a LUT which I import into Premieres Lumetri tool.
Now, this works with FilmConverts LUT generator, but when doing a regular export with more grade nodes I get these artifacts.

First one is FilmConvert, the next has more nodes on it.

 

[Christoffer Glans]

I found out that you can't use FilmConvert in the grade, together with qualifiers, masks or anything... whenever you do, you get these artifacts when outputting a LUT. So, you can only do basic grading... so, before this is fixed it's a bit useless.

 

[Marc Wielage]

This looks somewhat like a bit-depth problem, like a key or curve is yanking on 8-bit material too hard.

There are limitations as to what can be put in a LUT. As far as I know, the equivalents of Curves, Primaries, Contrast, and Saturation are about all you can do -- no keys, no windows, no effects. I've played and tested Film Convert quite a bit, and my observation is that there's nothing essentially in it that you can't do with the essential controls already in Resolve. The possible exception would be film grain, but even there you can use external grain or OFX plug-ins to add that (not within a LUT, of course). I'm very skeptical that Film Convert really makes digital material look like film, but I concede that some people may like the look, regardless of whether it is is or is not like film.

 

[Christoffer Glans]

This looks somewhat like a bit-depth problem, like a key or curve is yanking on 8-bit material too hard.

There are limitations as to what can be put in a LUT. As far as I know, the equivalents of Curves, Primaries, Contrast, and Saturation are about all you can do -- no keys, no windows, no effects. I've played and tested Film Convert quite a bit, and my observation is that there's nothing essentially in it that you can't do with the essential controls already in Resolve. The possible exception would be film grain, but even there you can use external grain or OFX plug-ins to add that (not within a LUT, of course). I'm very skeptical that Film Convert really makes digital material look like film, but I concede that some people may like the look, regardless of whether it is is or is not like film.

I use FilmConvert a lot because even if you can replicate the look, getting the conversion from a certain color science into a film look is not that easy and it's a good starting point for a grade. What I like with the grain is that it also affects the "blur" of the image together with the grain. Many other grain plugins only add grain, not converting it to a 16mm equal grain look.

I found that you can use qualifiers, but not use a parallell node structure while doing it, you can only do sequential grades. The problem occurs as soon as I use a plugin like FilmConvert (except when i'm exporting a LUT directly out of the OFX), windows, parallell nodes etc.

I'm not sure why it happens since it should just map the 3D cube. Broken to say the least.

 

[Marc Wielage]

I use FilmConvert a lot because even if you can replicate the look, getting the conversion from a certain color science into a film look is not that easy and it's a good starting point for a grade.

I would bet if you tried really hard, you could recreate that look. It just takes time, skill, and experience. There is no magic in the Film Convert software. To me, it's just a shortcut that neophytes use in lieu of relying on other methods to create a look.

If it gets you there, fine, but don't assume there aren't several other ways to reach that goal.