is our system ok to grade for theatrical screening?

[Joakim Ziegler]

I’m sure adding a gamma option to OpenDCP would be hugely useful. As I mentioned, you might want to look into white point correction too, I don’t know if you already do that.

We generally do all our grading in P3, and that’s much easier to convert to DCI X’Y’Z’, since it’s completely standardized, but it’s often useful to be able to convert from Rec.709 for material people bring in. For what it’s worth, EasyDCP is one of the better built-in conversions I’ve seen in DCP software, but we mostly make our own LUTs (we use CineSpace).

I think it might be time to look at OpenDCP again, maybe. DCP authoring is not really so complicated that we should be paying a bunch of money for the software, and most software is actually not great in functionality or UI. We use CineAsset, and it does the job, but I can’t say I love it.

—
Joakim Ziegler – Postproduction Supervisor

[Pepijn Klijs]

Joakim, please have a look at DCP builder. It has lot of functionality in there that you might like. I’m curious to see your opinion on it.

Editor/Colorist, Amsterdam, The Netherlands
http://www.pepijnklijs.nl

[Toby Risk]

Test different workflows and see what works for you.
Grade 709 / convert using open DCP
or grade XYZ with a xyz to 709 display lut on resolve, render to 16 bit TIFFS and just do a straight mxf package on openDCP

Alternatively if you can find any facility that runs QUBE as their DCP encoding software, its colour transform is near perfect, we’ve looked and looked and never seen any visible difference, after about 10 feature films and umpteen trailers/commercrials.

Now we grade features natively in p3 and render to XYZ. We only use 709 to XYZ for commercials as they are usually TV originated.

Colourist | Editor | Post-Production Consultant — 23 years at the post-production coalface, and still loving it.

[Mike Most]

Rec709 gamma may not be explicitly defined, but it is well known and common across platforms. Any software that is offering a Rec709 to X’Y’Z’ for a DCP needs to take that into account and do a gamma conversion to 2.6 (which IS defined for P3) as part of the overall conversion. That is the default in programs like Qube, even though it can be overridden by the user, and the reason I mentioned earlier that any such conversion should yield a proper result. I was unaware that there was no gamma conversion being performed in the software that was specifically being referred to, so I apologize for my ignorance in that regard……

[Joakim Ziegler]

Rec.709 display gamma is “well known and common” only to the extent that it’s between 2.2 and 2.4. Common values are 2.2, 2.35, and 2.4. There’s no standard or consensus more exact than that, if someone’s telling you there is, they’re incorrect.

I was going to link to Charles Poynton’s excellent article on the subject, where he describes exactly this de facto standard, but I can’t seem to find it on his site at the moment… I might just not be looking properly.

—
Joakim Ziegler – Postproduction Supervisor

[Juan Salvo]

Poynton is a very strong and vocal proponent of the BT.1886 standard and it’s corresponding 2.4 gamma. I think this is quickly becoming the defacto standard.

Colorist | Online Editor | Post Super | VFX Artist | BD Author

https://JuanSalvo.com

[Vagelis Kasapakis]

Thank you all guys,
all your posts are very helpful.
I want to thank Terence specially for creating and sharing openDCP which I have used sometimes with success.
I tried DCP builder these days and it has some interesting features, but it was much slower at encoding 1080p 16bit tifs to 2K jpeg2000 than openDCP, which was again slow. It took my 8core mac pro 50 minutes for a 5min clip. Is this normal? Is jpeg2000 encoding so heavy? I have read in forums people reporting 2x realtime conversion with 4core mac pro using easydcp.
Anyway, the DCPs created by both openDCP and dcpbuilder load perfectly in easydcp player demo and play in low res with ffmpeg (https://www.belle-nuit.com/open-source-dcp-player-proof-of-concept). Colors seem ok with both easydcp player and ffmpeg xyz to rgb conversion.
thanks again,
vagelis

[Pepijn Klijs]

I’m on a i7 3930k 4,2 ghz (6 core) and Im getting 4fps in DCP builder and OpenDCP. Only finaldcp gives me an impressive 24fps render. I don’t know how fast easydcp renders, but I also don’t care, as Im doing dcp’s sporadic and cannot justify its cost.

Editor/Colorist, Amsterdam, The Netherlands
http://www.pepijnklijs.nl