DPX log workflow

[Rolf]

I have 2 questions about workflow within Nuke.

When working with DPX log files, what is the correct method of viewing the files when working with them? Nuke’s Read node has identified the file as cineon. I am confused as to what I set the viewer LUT to be when I am working with the file.

Also, if I have linear or 8bit elements (stock footage like smoke or flames) how do I deal with the different color spaces when I am comping so that is looks correct.

Thank you,

William

[Anonymous]

vanilla log dpx’s should typically be set to cineon in the read node, and nuke will do this by default.

then, as you’re working in linear space, just set your viewer lookup to typically sRGB or whatever lut you use to normalize for your monitor.

it is possible to have such a thing as a linear dpx, so, you know… if for some reason things look wonky, you might check your files.

as for other elements, everything in nuke is dropped in with the intention of having any colorspace undone in the read and flattened to linear, and then can be lutted from there. so usually your 8 bit sources will come in set to sRGB and exr’s might be linear, etc. and then you apply the viewer sRGB lut to invert the monitor gamma.

the defaults are very well chosen, should get you the right settings most of the time.

[Annett Duffy]

Thanks Jbills.
I just found out the DPX files were exported using REDCINE-X. Does anyone know the LUT in Nuke that should be applied to these files (my guess is RedLog)? I have downloaded the software and looked at the manual but it doesn’t say. The files are 10bit.

[guillem ramisa]

@Rolf 32717 wrote:

Thanks Jbills.
I just found out the DPX files were exported using REDCINE-X. Does anyone know the LUT in Nuke that should be applied to these files (my guess is RedLog)? I have downloaded the software and looked at the manual but it doesn’t say. The files are 10bit.

You have to ask the person that did the Redcine export. You have quite a few options when it comes to choosing gamma for exports.

[Annett Duffy]

The REDgamma default was used.

[guillem ramisa]

@Rolf 32719 wrote:

The REDgamma default was used.

I think redcine defaults to exports like this – Color space: REDcolor and Gamma space: REDgamma
It’s a bit of a jungle with all of those export settings and I’m no expert myself but REDgamma isn’t a log format really so using REDlog to make the DPX linear would be wrong.
REDgamma is supposed to be (I think) something that is possible to grade but still look “nicer” (for the end client) than something like a regular log file.
The problem is that I believe there is no option to make that kind of gamma linear in Nuke. You have REDlog and REDspace and that is not the same.
So if you really need to know that you are working with your dpx sources in linear space in Nuke you should probably ask for an export with another gamma encoded, like REDlog for example or maybe PDLog685 (that I believe is RED’s flavor of Cineon but I’m not sure it’s exactly the same). You could also get the original R3D file of course, even better I guess.
I actually tested a few things in how nuke reads R3D files vs RED DPX exports with various gamma encodes. First I had the original R3D with a read node, everything set to linear. Then imported the same clip but as various dpx exports with REDLog (read node set to REDLog) and PDLog685 (read node set to cineon) and they all should look the same, or at least I thought so? They were pretty similar but varied a bit. I think the REDLog DPX was the one that came the closest to the directly imported R3D file. Hmm, a bit disturbing, but I’m not surprised. RED files are a mess.
And as mentioned earlier, I’m no expert here so you shouldn’t listen too closely. If there is anyone else out there that knows all about the difference between REDLog and REDLogfilm for example I’d be happy to hear all about it 🙂

[Shekhar Rathore]

Just did a quick test for you that may help. I took an R3D into REDCINE-X and kicked out a 10-bit DPX sequence using REDcolor as the colorspace and REDgamma as the gamma space. I brought that image sequence into factory default Nuke (viewer set to standard sRGB) and set the read node to sRGB. As far as I can tell, the image in my Nuke viewer looks absolutely identical to what I see in my REDCINE-X viewer. Also, I get the same results when I bring the R3D directly into Nuke, set the read node to sRGB, and then set the debayer options in the same node to REDcolor and REDgamma respectively. (and set to color v2)

[Author]

Posts