Probably a weird question, but is there any way to convert what is displayed in the VFB to 8-bit via a layer (and not via display correction)?
The reason I ask is that I have a set of LUTs that only seem to work on 8-bit images unfortunately and it’s a bit of a hassle to bring a render into PS to see the LUT’s effect…
There’s no way of doing that; you can view the pixel values in 8-bit though (rollout at the bottom, next to the pixel values). Mind if you send the LUT so we can troubleshoot?
I would love it if you could take a look. support@chaos.com?
Or the contact form.
it’s not the bit depth but certain colour space and encoding (like log) combination that is expected by every lut. what is your lut made for?
I had hoped you’d chime in. I have tried (I think) every combination of settings to no avail.
It’s mimicing the RAW->JPG conversion that happens in camera on a fuji x100v (and once that is successful a GFX too).
I am making it specifically for the Vray vfb.
It’s been an extremely convoluted process thus far.
this is what I found:
Microsoft Word - F-Log2_DataSheet_Ver.1.0E.doc (fujifilm-x.com)
looks like BT.2020 colour space and F-log2 encoding. is this what you need for your lut?
Despite this already being beyond me, this isn’t quite what I’m after. I don’t believe there’s any resources out there that are for what I’m trying to achieve.
Fuji has a bunch of film simulations and I’m attempting to replicate these. The film simulations are only applied in-camera as the raw is converted into a JPG meaning the results are only available in 8-bit.
I have taken series of photographs of colour charts and calculated the difference between these and reference values and have ended up with a LUT via several pieces of shitty software which don’t really allow any control over colour spaces or encoding.
They seem to work perfectly in photos in 8-bit, not not in a 32-bit color space or in the Vray vfb. Happy to share what I have with you in case you’re curious to try and solve my problem 
so the luts you created require you to find Fuji ODT (output device transform), recreate it in frame buffer (or with ocio).
can you output one of the log encodings from your camera? it would be much easier as it is known starting point (fuji log or log2).
or maybe you can just measure the difference between „normal” output and fujii log.
might be enough.
If I have measured the difference between the refernce values specified by the manufacturer of the color chart. and the output from the camera, this should work (as it does in 8 bit in photoshop). I suppose I could try and make a profile that gets the VFB output to match my starting point… I fear that won’t work as the whole 32-bit → 8-bit mismatch is going to happen again.
it would be:
raw render >> curves adjustement (most likely, or just lut if fuji log does not reach above 13.5 float) to encode into correct log >> lut (that would consist of acescg to BT.2020 conversion and the “fuji film look”.
this is how to make precise curves in VFB:
https://forums.chaos.com/forum/chaos-common/chaos-common-public/1199171-lin2log-lut?p=1203476#post1203476
I’m afraid I understand close to nothing of what you’ve written.
Edit: Ok I am making progress. Thanks for helping to spark some ideas on what the issue might be.
Aleksandar, you can ignore my mail to support for now
Edit: Duplicate post. What’s up with the forums atm? Really slow and lots of errors when trying to post?
I found this from Fuji:
GFX100_FLog_FGamut_to_WDR_BT.709_33grid_V.1.01.cub e LUT for F-Log (Look Up Table) / IDT for F-Log (Input Device Transform) | FUJIFILM X Series & GFX – Global (fujifilm-x.com)
it looks like Fuji default ODT for BT.709 displays. Not sure but looks ok.
I’m attaching lut that would take you from acescg raw render to Fuji F-Log.
put GFX100_FLog_FGamut_to_WDR_BT.709_33grid_V.1.01.cub e on top.
this might be the default Fuji look. I guess.
edit: issues with forum uploads
Thank you! Should come in handy in future
is there any Fuji software supplied with the camera? it should let you use those film emulations on a single raw photo, maybe even output this to log encoded 12 bit file. would make things much easier.
So the software that comes with the camera is operated on a PC/MAC but the processing happens in-camera (while it’s plugged into your workstation). It’s a bit of a black box and the RAWs do not get the same treatment unfortunately. This is why I am trying to match these 8-bit jpegs that come out of the camera.
I have made a lot of progress in the last 24 hours and am very very close to getting what I wanted. The problem I had was that I was matching “corrected” colors in sRGB. I remade the color chart in max which gave me raw colors to match with which has largely solved my problem.
There’s still a lot of stuff to do with color spaces and display correction that I really have a hard time understanding which I’m sure would have gotten me there sooner and would help me close that last tiny 1% gap between what I want and what I get.
good luck.
and please share results.