FORUMS: list search recent posts

Grading adjustment in Resolve for DCP creation

COW Forums : DaVinci Resolve

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Jean-Christophe savelli
Grading adjustment in Resolve for DCP creation
on Apr 23, 2012 at 12:07:34 pm

Hello everybody,
I need your advices about grade adjustment for DCP creation on Resolve.
I grade my short on Davinci on a rec709 monitor (legal video…etc..) so now i have to export it for DCP creation. So i have many interrogation about this.

- The gamma between 709 and DCI is not the same (2.2 vs 2.6)
- the color range is not the same…

So can simply convert my 709 grading with gamma compensation to be sure that it will be ok for DCP ? use unscalled full range parameter in Resolve ?
I really don't know the workflow for this kind of thing, i really need to be sure that i will make the good thing for my movie. In 709 the film is ok and i really would like to keep this "ok" for the DCP.

Thanks a lot for your help

JC


Return to posts index

Jack Jones
Re: Grading adjustment in Resolve for DCP creation
on Apr 23, 2012 at 2:36:22 pm

I don't know much about the Resolve specifics, but the following should be helpful;

You should make your DCP from your DCDM.

- The DCDM should be made up of full range 16-bit TIFF files, ideally broken down into reels.
i.e. filmtitle_r1_10000001.tif
- It should have a gamma conversion to match DCI spec of 2.6.
- It should be mapped into the XYZ colorspace using either a LUT or a Gamma Matrix.

Practical guidelines are available here: http://www.knuterikevensen.com/?p=312 and a full list of software/hardware are available on the DCP Wikipedia page.

Jack Jones
Freelance Nucoda/Baselight/DaVinci Colourist
--
http://www.jackjonescolourist.com


Return to posts index

Jean-Christophe savelli
Re: Grading adjustment in Resolve for DCP creation
on Apr 23, 2012 at 3:30:48 pm

Thanks for the link Jack.

So for Davinci user, do you think a need to check all my grading with unscalled full range activated or not ?


Return to posts index


Chris Martin
Re: Grading adjustment in Resolve for DCP creation
on Apr 23, 2012 at 5:06:14 pm

JC,

Are you making the actual DCP yourself or is another facility? If another facility is doing it then you should talk to them as it may be as simple as delivering them grading media and identifying that the working viewing environment was 709. The facility probably already has a process to transform the 709 to a DCP color environment (xyz, gamma 2.6).

If you are making the the DCDM yourself, which means creating a specific deliverable that is prepped for making a DCP, then as someone else has pointed out then you'll need to use a LUT that properly transforms the project from one graded in a rec709 to one that accounts for the xyz color space of DCP. This transform LUT when properly used will compensate for both the xyz color as well as the change from 2.2 to 2.6 gamma environment. The great thing is this is all math and you don't need to do any regrading to account for anything assuming you've been grading in a well calibrated rec709 environment and you are using a proper rec709toXYZ LUT. I know Resolve comes with a standard RGB to XYZ LUT but have not tried this one out.

Also if you're doing a DCDM, make sure you are also delivering media that fits proper DCDM specs. We do 16bit tifs, converted to xyz color, and usually resolution will be 1998x1080 - 1.85 ratio (unless anamorphic). This means if you are working 1920x1080 you have a decision to make to either protect aspect ratio and box the 1920x080 in 1998x1080 canvas or crop top and bottom.

Still, if a facility is doing the DCP then there's a good chance they could do all the above.


Cheers, Chris


Return to posts index

Jean-Christophe savelli
Re: Grading adjustment in Resolve for DCP creation
on Apr 23, 2012 at 10:43:33 pm

thx chris i do it by myself because i don't have the money to let a company doing this for me.

Waht i plan to do after reading all your advices :

- don't touch my grade, keep it in rec709 and in legal video
- upscale to 2k (2048x858, 2.39 ratio)
- export from resolve in dpx sequence still in rec709

i will use opendcp to create the dcp package. I see in opendcp that we can feed with rec709 dpx sequence.

Is it something bad with this workflow ?


Return to posts index

Jack Jones
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 6:25:55 am

With OpenDCP you have to feed it full range files otherwise your blacks will be lifted.

Full range, Rec. 709 16bit TIFF images with your chosen scaling for full, scope or flat. Do the Rec. 709 to XYZ transform in OpenDCP (which will account for the 2.6 gamma). Obviously ensure Logarithmic is unchecked.

Remember that with OpenDCP you have to compile the audio separately. You also need to know what servers it'll be playing on as to whether or not you can create SMPTE packages or if you can only create INTEROP 24/48fps.

Do a 10 second test and check it in the EasyDCP player demo. Grab a still from it and do an XYZ to Rec. 709 transform to check it's correct - the licensed software will do this transform but that's a semi-work around.

Most importantly be sure to speak with whoever is screening it and find out the exact details of what you can provide.

Jack Jones
Freelance Nucoda/Baselight/DaVinci Colourist
--
http://www.jackjonescolourist.com


Return to posts index


Juan Salvo
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 6:47:19 am

I've used openDCP in the past and have had major compatibility problems.

Someone looking to roll their own dcp obviously won't be grading in DCi space. I hope they have a properly calibrated 709 monitor, otherwise everything else is pointless.

For colorspace transforms I'd actually recommend AE, particularly if you're going the freebie route. There are a lot of great tutorials on this. But basically you grade 709 limited or full your choice, just know which. Then export out a qt. bring it into ae and using the interpret menu, define its colorspace, either 709 limited or full. Create a new comp with it, set your comp colorspace to DCi xyz then render out to an image sequence, and proceed with the dcp.

There are some not terribly expensive commercial software packages, that make much more standard and reliable dcps and will also do the colorspace conversion for you. I would strongly recommend one of these.

online editor | colorist | VFX | BD author

http://JuanSalvo.com


Return to posts index

Terrence Meiczinger
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 12:23:44 pm

Juan,

I'd be interested in hearing about your compatibility issues you have experienced with OpenDCP. It's been tested successfully against all the major vendors. If it was sometime ago, you were probably caught up in the MXF Interop and SMPTE switchover. SMPTE is the default for OpenDCP, but there were a lot of broken SMPTE implementations in field which may have caused problems. If you still have any information, I would appreciate it, so if there are problems with OpenDCP I can work to fix them. Thanks.

-Terrence


Return to posts index

Juan Salvo
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 4:17:32 pm

Hi Terrence,

It was the smpte / interop switch over. Particularly on the Dolby server, as we tested on various others and it was fine. I got burned pretty bad on that one (really, really embarrassing) and so haven't looked at OpenDCP again. This issue may have been dealt with since, but I haven't even tried. To be honest, using openDCP isn't worth the risk to me, better to use commercial solutions with relationships to the server manufacturers.

With regards to the broken smpte implementations, you're probably right, problem is exhibitors and server manufacturers have been painfully slow in updating these.

-Juan

online editor | colorist | VFX | BD author

http://JuanSalvo.com


Return to posts index


Terrence Meiczinger
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 5:03:29 pm

There was a period where firmware versions were all over the place. Even several of the big commercial DCP encoders had serious compatibility problems with SMPTE. The push for DCI compliance this year has improved things a lot. I am surprised you had issues with the Dolby though, considering that is what I use and it was probably the most tested server, but again I always had updated firmware.

I totally understand your position. As with any open source software, mileage varies, especially software that is in development. Obviously, I have no financial gain if somebody uses OpenDCP or not, but I certainly want make it as solid as possible and any feedback helps.

I appreciate your responding back to my questions.


Return to posts index

Juan Salvo
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 5:20:28 pm

I appreciate your asking the questions.

Glad to see the development of OpenDCP is ongoing. We all benefit from innovation and competition. So thank you for that.

online editor | colorist | VFX | BD author

http://JuanSalvo.com


Return to posts index

Jean-Christophe savelli
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 10:20:22 pm

it seems that you are involve in opendcp, i have a small question.

in the jpg2000 creation window, i see that we can select both sRGB or REC709 as input source. Does it meen that opendcp jpeg2000 can simply and easily convert REC709 source to a good XYZ version without need to adjust source in full range mode ?


Return to posts index


Knut Jansohn
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 11:43:54 am

[Jean-Christophe savelli] "The gamma between 709 and DCI is not the same (2.2 vs 2.6)"

That's not correct. See http://forums.creativecow.net/readpost/277/8229

If you did the grading in a dark enviorement with gamma 2.2, then your midtones will appear to dark with gamma 2.6 in a dark ambiance (cinema).

Regards
K.


Return to posts index

Jean-Christophe savelli
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 11:50:17 am

Ok i will do some test with AE for the export : both with full range and limited range to compare.

And yes you right Juan, the image will be darker, it is because i'm quite worry about that gamma question a the best solution to have a final dcp close to my graded 709 version, even the 709 gamma is 2.2, 2.4 or 2.5 it will be darker in DCP and i need to find the best solution to manage this.


Return to posts index

Knut Jansohn
Re: Grading adjustment in Resolve for DCP creation
on Apr 24, 2012 at 12:03:54 pm

You could solve the gamma-issue with a 1d-lut. How to is well described in the resolve manual.


Return to posts index


Jean-Christophe savelli
Re: Grading adjustment in Resolve for DCP creation
on Apr 25, 2012 at 3:20:40 pm

Thx for the information Knut so i look in the manual but i don't exactly know what i'm looking for ?
something like "1d lut gamma compensation" ?


Return to posts index

Knut Jansohn
Re: Grading adjustment in Resolve for DCP creation
on Apr 25, 2012 at 4:42:50 pm

[Jean-Christophe savelli] "something like "1d lut gamma compensation" ?"

No, it's not exactly that ticket. 'Only' how to deal with luts.
But if you could calibrate your monitor to the propper gamma a simple node on track will solve it too.

Or try this one: http://forums.creativecow.net/readpost/277/5082


Return to posts index

Jean-Christophe savelli
Re: Grading adjustment in Resolve for DCP creation
on Apr 25, 2012 at 4:45:26 pm

It's exactly what i finally done a node with black lift adjusted and a small gamma adjustment in the mid tone.


Return to posts index

Jean-Christophe savelli
Re: Grading adjustment in Resolve for DCP creation
on Apr 30, 2012 at 2:59:40 pm

Here is the result : everything seem to work, i will make new test tomorow but for the first try i'm quite happy.

Here is what i do :

- export my entire film from davinci in prores422 HQ REC709 unscalled full range.
- upscale and convert in TIFF 16 bits 2048x858 REC709 (lin luma)
- do the REC709 TIFF to JPG2000 XYZ in openDCP

I have a little désappointent with chroma level, little desaturation after XYZ conversion (3 or 4 % desaturate) but my black are black.

Do you think i have to adjust a little my chroma level in Resolve ?


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]