Use OOC JPGs to apply film simulations to raw files through LUT adjustments?

[pipet]

I'm a Fuji camera user and very much like the film simulations that can be applied to the out-of-camera (OOC) jpgs. Usually I shoot raw + jpg. The Fuji jpgs are very good, but once in a while I have to develop from raw and would like to apply these film simulations to the developed raw file.

This can be done e.g. in Lightroom that includes profiles for these film simulations. I'm not a Lightroom user, however. As an alternative, there is a series of HALD CLUTs for Fuji film simulations created by Stuart Sowerby. My workflow is to demosaic the Fuji raw files with Iridient X-developer (default settings) and import the resulting DNG file into Affinity. Now I can develop the DNG file in Affinity (not making any color or brightness contrast adjustments, as recommended) and apply Stuart's LUTs. These get me into the right ballpark, but with somewhat challenging images they are not spot on.

So I was thinking, that it should be possible to use the OOC jpg with the film simulation already applied in camera as a reference to guide the color adjustment of the raw file. So, naively I developed one of the DNG files (without any adjustments) and exported it to jpg for use as the identity image. I then applied a LUT adjustment with 'Infer LUT' and selecting the exported jpg as identy image and the OOC jpg as target (for lack of a better word) - but nothing happened.

So I'm wondering a) why is that not working? Do the LUT files need to confirm to a standard format (I have seen the matrix layout of Stuart's LUT files)? b) If the latter is the case, how can I build a proper LUT file from my identity jpg and the OOC jpg? or c) is there a more straightforward way to apply the color characteristics of the OOC jpg during raw development?

[v_kyr]

I recall that there was some problem (known issue) with LUTs lately, so you might want to see if it makes a difference or behaves more correct, if you try them out instead in RawTherapee.

[pipet]

Thanks for the hint. The RawTherapee result is in fact much better. I'd still be interested in how the OOC jpg could be used to influence the color characteristics of the raw development, either through LUTs or other means.