2K log DPX RED workflow with RESOLVE

[John Edwards]

Hello,

I'm trying to develop a workflow based around 2K log DPXs from RED R3D sources. I've come across a lot of conflicting information regarding this and the creation of log DPX files from R3D's. I'm looking for the following or something similar;

Shoot RED>Transcode to ProRes/DNxHD in RedCine/FCP/Avid>Offline Edit>XML/EDL>Clipfinder or CrimsonWorkflow & RedCineX>2K log DPX (Redlog or PDlog?)>Resolve (With LUT? Which? Where?)>2K DPX/QT etc

The reason I want to do this is I don't have a RedRocket yet and can only get a realtime debayer at 1/4 res. This would let me stay realtime at 2K (and based from testing with up to 7 100% blur nodes!). My logic is that I can keep the quality of the R3D by using LOG, while not suffering the overheads of the debayer. Also, I'm looking to see a good-looking/normal image in Resolve with a LUT as a starting point, I don't want to grade the log directly! Ideally I would use a LUT that would take the Redlog or PDlog DPX and display the RED footage as it looks in RedSpace/RedColor. Also, I don't mind 'waiting' for the debayer during the DPX conversion, my machine is pretty quick.

Please get in touch if you've used this workflow or a similar one with success.

Thank you,

 

[paulherrin]

http://reduser.net/forum/showthread.php?61375-Ask-Mike-Most-Anything

 

[Nick Shaw]

Don't use REDlog or PDLog, they are now superseded by REDlogFilm. You can then use a display LUT to show that as e.g. REDgamma while grading in log. I just finished a project at Technicolor using exactly this approach, and it worked extremely well.

 

[Marcus Struzina]

Hi Nick please forgive the uninformed question, how was the display LUT generated, or is there a standard REDlogFilm to REDgamma display LUT available ?

 

[John Edwards]

Yes, where is that LUT? Is there even a simple RedLogFilm to Linear available? Or can you just use film log luts?

I'm going to do my on tests, but it would be really helpful if I had access to the right LUTs.

Thanks,

 

[John Tissavary]

It's not a LUT in the traditional sense, it's the matrix you select in the Red SDK transcode. Should be one of the options in the color tab of the R3D settings. I don't have Resolve 8 here (we're on an older version), so not positive, but that's how it works in other systems via Red SDK.

 

[John Edwards]

Yes, but you can't access that matrix when reading DPX's, only R3D files. I'm looking to use RedLogFilm 2K DPX's (from R3d's) with a LUT to get an image that looks similar to an r3d with RedColor2 and RedGamma matrices applies. I suppose I could make my own LUT in resolve or Lightspace CMS (If I bought it) with a bit of work, but surely this matrix/lut can be gleamed and created from the SDK or other public LUTs?

 

[John Edwards]

RIGHT....My colorist friend (Toby Tomkins) made a LUT that converts REDLogFilm/RedColor2 DPXs to something very close to REDColor2/REDGamma2 linear (i.e. what you would see with these settings applied to an R3D file in RCX/Color/DaVinci). If you would like this LUT, please PM me.

 

[Nick Shaw]

…is there a standard REDlogFilm to REDgamma display LUT available ?

No, but I have built one. However I did it for another project I am working on, so I cannot give it away for free.

 

[Marcus Struzina]

Nick of course completely understand, thanks for clearing up the way to go though. I think I'll first try manually matching a redlogfilm dpx ( Macbeth + greyscale file export from RedcineX) to a Redgamma dpx ( same file exported from redcineX with Redgamma instead ) in Color and generating a rough Display LUT from there. Would checking the subsequent exported DPX files against each other in photoshop to see how well they match make sense ? Guess I'm abit off topic as I'm still working with Color.

 

[Luis Otero]

The custom LUT are specific for your reference projector or monitor. Go here, and talk to Evangelos ( http://www.motionfx.gr/film-overview.html ). He will guide you to be within +- 3% of margin of error. The results are just incredible...

 

[Luis Otero]

Yes, but you can't access that matrix when reading DPX's, only R3D files. I'm looking to use RedLogFilm 2K DPX's (from R3d's) with a LUT to get an image that looks similar to an r3d with RedColor2 and RedGamma matrices applies. I suppose I could make my own LUT in resolve or Lightspace CMS (If I bought it) with a bit of work, but surely this matrix/lut can be gleamed and created from the SDK or other public LUTs?

John,

The "trick" it to get your R3D to behave as a Cineon image (just ask Graeme): RedColor2 and RedlogFilm, as Nick pointed out, will take you there. Once you have gotten there, then using the LUT that was created as a result of profiling you display/projector to be in a film "color space", grade your material. As a final step, for rendering, use the conversion LUTs to deliver the different versions that are appropriate to the outlet intended (Rec.&09, sRGB, DCP, etc).

But everything starts with profiling your display, either monitor or projector. After that, have fun grading using R3Ds without the need to first create DPX sequences. Reserve that step for the deliverable(s).

 

[M Most]

John,

The "trick" it to get your R3D to behave as a Cineon image (just ask Graeme): RedColor2 and RedlogFilm, as Nick pointed out, will take you there. Once you have gotten there, then using the LUT that was created as a result of profiling you display/projector to be in a film "color space", grade your material. As a final step, for rendering, use the conversion LUTs to deliver the different versions that are appropriate to the outlet intended (Rec.&09, sRGB, DCP, etc).

But everything starts with profiling your display, either monitor or projector. After that, have fun grading using R3Ds without the need to first create DPX sequences. Reserve that step for the deliverable(s).

I might be misinterpreting, but the original poster never said anything about film, and didn't imply that he wanted to push his images into a film color pallette. All he asked about was how to properly set up a processing path for seeing a proper image on some electronic display, which he didn't specify but I assume to be either digital projection or a monitor. You don't need any of what you're talking about for that, all you need is a display that's set up properly to that display's spec, and either a custom curve or a 1D LUT to go from RedlogFilm (roughly Cineon) to either video or digital cinema space. You can make such a LUT on Arri's website, or you can design a custom curve in Resolve easily enough.

If filmic colors and a film result are desired, what you say is one way to get there. There are others as well. But if that is not what was called for, what you're suggesting is not the most sensible approach.

 

[Luis Otero]

Mike,

I know that it is not your preferred path, which I respect. If it is not intended for film, then the system is set to the appropriate outlet it is intended to be used in.

I think in life there are more than one path to get where you want to go. Some paths are by intuition, others are guided by a "GPS", if I may use such analogy. The one I described above (guided by a "GPS") has provided us the +-3% accuracy compared with the film-out tests in all our projects since we implemented it; and a 1D LUT was just not enough for us to meet such standards. So, for us that fact is settled since it has been measured, so we have solid data to support it. By the way, implementing it was very sensible at all levels ($, time, etc.). We are small, and poor, so we needed to use a very sensible path.

So, I like to share it with other fellows redusers so they can hear about various experiences, and use them. That way anyone can arrive to their own conclusions based on the results they obtain.

Nevertheless, based on your posting I assume that we can agree that without having your image provider, monitor or projector, properly profiled and/or calibrated via any system you prefere (LUT, icc, etc) is just essential before venture to move via any path.

 

[M Most]

Nevertheless, based on your posting I assume that we can agree that without having your image provider, monitor or projector, properly profiled and/or calibrated via any system you prefere (LUT, icc, etc) is just essential before venture to move via any path.

Yes, a display has to be properly set up. But that wasn't the question being asked here. The question was how to get from RedlogFilm to something that is, well, viewable and correctable on a "normal" display. The only time a 3D LUT is required is when there is a color space conversion, or if the LUT is being used as a color correction that incorporates saturation changes. That's not the case for the original poster, or at least, there was no indication that it's the case.

 

[Nick Shaw]

The LUT I was referring to is a 1D LUT which converts material rendered as REDlogFilm to appear as if it had been rendered as REDgamma. I have converted it to a 3D LUT where appropriate for particular applications, but it does no colour-space conversion.

I find it a very useful LUT to grade through, as the DP sees the same REDgamma image they saw on set as a start point, but the colourist is working in log, and the image responds to grading accordingly. The colourist at Technicolor agreed with me.

 

[Marc Wielage]

The LUT I was referring to is a 1D LUT which converts material rendered as REDlogFilm to appear as if it had been rendered as REDgamma. I have converted it to a 3D LUT where appropriate for particular applications, but it does no colour-space conversion.

Mike above is right in that there are many ways to skin this cat, and some methods are more appropriate than others.

I've used Log-to-Lin converters within conventional 2K color correctors to just convert R3D files to linear color space for color correction on the fly; I've used custom LUTs with Luther (the DFT box); I've used custom and preset LUTs within Northlight; and I've used custom curves and other adjustments to get there on more limited HD systems. Not all color correction systems are comfortable using R3D files directly; for some workflows, all-DPX may be more convenient.

A lot depends on the specific display device being used and the intended delivery of the material. Assuming it's Rec709 for both, it's not difficult to do given some experience and a calibrated display. The key is finding a LUT that still retains enough range for the colorist to do their job, and that's a subjective call. RedcineX has the tools to get close, and the previous advice in this thread will work. I would strongly advise doing a workflow test with several different types of set before deciding on a common path (RedGamma2 vs. RedLog, etc.).

BTW, note that Cineon files are essentially DPX files with the older Kodak-created headers. My opinion is that DPX is the only thing to worry about for most post houses, unless for some reason they're specifically using Cineon software (which would be unusual in 2011).