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michael stirling
DCP looked lifted
on Aug 28, 2013 at 9:16:36 am

Hi

I've just got back from a screening of feature and trailer DCPs I created and the feature looked so bad. I'm not the Colourist on this job, just QCing the grade and delivering. We screened at MPC so I'd be 99.9% certain the room was correct.

The projects were delivered to me as ProRes 422HQ

For the trailer I rendered to 16bit tiff RGB and did the the colour transformation in easyDCP - that looked great.
The feature I rendered 16bit Tiff with the Resolve rec7509 to XYZ LUT - it looked really bad, mostly due to lifted black level which really showed up the grade and noise (it was mostly shot in a forest at night).
Anyone had a similar issue with the Resolve LUT or can throw any light onto what could've happened?

Thanks,

Michael.


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Margus Voll
Re: DCP looked lifted
on Aug 28, 2013 at 1:09:16 pm

easyDCP does not make the colour conversion by itself?

--

Margus

http://iconstudios.eu
https://vimeo.com/iconstudioseu/videos

DaVinci 9, OSX 10.7.4
MacPro 5.1 2x2,93 24GB
GTX 470 / Quadro 4000
Multibridge 2 Pro


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michael stirling
Re: DCP looked lifted
on Aug 28, 2013 at 1:41:47 pm

It does...

That's what I did for the trailer. I'm going to be remaking the feature DCP using easyDCP for the colour transformation. My question was more does anyone have an opinion why the feature where I used to LUT from within Resolve instead looked so bad.

Thanks,
Michael


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Mike Most
Re: DCP looked lifted
on Aug 28, 2013 at 2:39:19 pm

The gamma of P3 (the setup used for DCI spec projection) is 2.6. The gamma for Rec 709 is somewhere between 2.2. and 2.4. If you converted from Rec709 to P3 as part of the DCP manufacturing process, but you graded in Rec709, that will lift the image so that it looks correct on a digital cinema projector. However, if you told the theater to set up for Rec709, and/or the conversion was done twice, that would get you the results you're describing.


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Margus Voll
Re: DCP looked lifted
on Aug 28, 2013 at 2:47:17 pm

Seems reasonable to me.

I have seen this here also.

I have not done dcp myself but i have seen similar problems around here also
with other people doing the conversion.

--

Margus

http://iconstudios.eu
https://vimeo.com/iconstudioseu/videos

DaVinci 9, OSX 10.7.4
MacPro 5.1 2x2,93 24GB
GTX 470 / Quadro 4000
Multibridge 2 Pro


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TJ Kim
Re: DCP looked lifted
on Aug 29, 2013 at 3:13:49 am

Have you tried to ProRes(HQ) in DATA level? It might work...


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michael stirling
Re: DCP looked lifted
on Aug 29, 2013 at 9:00:39 am

The easyDCP manual says it does this:



Is that doing more than the rec709toXYZ LUT in Resolve?


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Mike Most
Re: DCP looked lifted
on Aug 29, 2013 at 2:41:31 pm

That's fine as long as you're handing it full range video at the beginning of the chain rather than video scaled. If you're using a video scaled image, the delog step is going to yield a linear light image that is too light. This is made even worse when the 2.6 gamma is introduced. Rec709 video is meant to be viewed in a video scaled environment (that's what monitors are set up for), but a DCP incorporates no such thing. So to look correct, you need to be feeding that processing chain full range material, not scaled. One way to check if this is the case is to apply a video to full range LUT prior to sending the material to your DCP program. That should fix the issue.


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michael stirling
Re: DCP looked lifted
on Aug 30, 2013 at 9:55:02 am

I think that everyone is misunderstanding the problem I'm having. There is nothing wrong with easyDCP's colour transformation. Putting a rec709 file through the easyDCP chain looks great in the cinema in XYZ space there is no issue there - no video to data level LUT is required. This is now my workflow.

It's Da Vinci's rec709-XYZ LUT that looks bad. It does look like it needs a video to data LUT then the rec709-XYZ LUT but I'd have thought that it should also presume the start point of rec709 was video levels and transform accordingly.

This all might have come about because the source material was graded ProRes HQ at video levels and Resolve could be expecting the source to be full range when applying the LUT?

M


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Mike Most
Re: DCP looked lifted
on Aug 30, 2013 at 2:36:42 pm

Resolve always works internally in full range levels, and should generally be left that way. That's why there is a selection to "monitor using normally scaled video." That adds a full to video LUT on the output path, but not on the processing path, which allow for proper creation of different deliverable formats that may or may not require it. If you're monitoring with a Rec709 type HD display (as opposed to a digital cinema projector) you would have this switch enabled. When you make the DCP, the full range levels will be present and everything should come out right. If you work on a video monitor and do not have this enabled, you'll be making the compensation manually, creating a file that is inherently graded to video levels, and you'll have exactly the problem you described. In most DI theaters, the switch is disabled so that the digital cinema projector is being fed the levels it expects.


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Simon Blackledge
Re: DCP looked lifted
on Sep 18, 2013 at 12:11:33 pm

So basically if you have a file thats VIDEO and you have to playout to dcp you need a Video to FULL Lut .

So where can one find that?

Or

Can you load the file up. Tell Resolve in clip attar that its video
Goto delivery and set it to DATA and render out a data version ?

Will delivery stretch it out ?

S



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Ernest Savage
Re: DCP looked lifted
on Feb 22, 2014 at 9:04:02 pm

Hello,

After reading a 100 or so blog posts, I think I have this answered, but I have a few questions.

Background:

Shot Arri Alexa ProRes 4444 2k – ingest into Resolve – grade – output to Bluray DVD/web for festivals screeners and finally to DCP for digital projection at film festivals.

System config:

Resolve 10.1 – Decklink Extreme – HD-SDI via BNC cable – Panasonic BT-LH 2600W.

The process I should follow?:

I understand the difference between Rec709 video levels 64-940, and full range data levels 0-1023. From what I’ve read in the blogs, If I’m viewing through my HD broadcast monitor (the BTLH), then I need to set resolve to Rec 709 video levels 64-940). After grading, the DCP house says I should render out full range TIFFs (since they are 16 bit and DPX is lower, 12 bit, or 10 bit). The DCP house will then convert my blacks from 64 to 0 and my whites from 940 to 1023. The DCP house says they should able to match my look within a 4% margin of error.

My questions:

When I set Resolve to Rec709 FULL RANGE, instead of VIDEO LEVELS, I see the darker blacks, in my BTLH. What am I seeing? The image seems to represent more accurately what I’m seeing in my internal resolve scope. In other words, when I bring my blacks close to 0, and Resolve is set to rec709 full range, the image in my BTLH looks like the blacks are close to 0. When I set to video levels, my image looks washed out compared to what my internal scopes are representing. I know Resolve always works in 0-1023, but what am I seeing in the monitor? Can the BTLH represent 0-1023? I’m pretty sure not, but hoping some how it does.

Should I just work in Rec 709 video levels, use external scopes, and let DCP house adjust my blacks and whites? How will chroma be affected?

Thanks, you folks are a wealth of knowledge.


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Mike Most
Re: DCP looked lifted
on Feb 22, 2014 at 11:10:14 pm

>>Should I just work in Rec 709 video levels, use external scopes, and let DCP house adjust my blacks and >>whites? How will chroma be affected?

I'm glad you asked that question at the end of the post, because the answer to that is yes. Assuming they know what they're doing, the company making the DCP should be able to apply transforms for the three major differences between your Rec709 targeted material and the digital cinema format. Those three things are color space (including white point), gamma, and running speed (23.98 to 24) for both picture and sound. Your knowledge base and your equipment seem to let you work in video space just fine (assuming you're looking at a properly calibrated monitor). But digital cinema is not video space, and having them ask you to go "half way" by delivering 12 bit TIFF files - even though they will, by definition, be in the wrong color space and have the wrong gamma - tells me that either they are giving you bad direction, you're asking the wrong questions, or both.

What you need to do is turn out a video product you're happy with. What the company making the DCP for you needs to do is take that video product - in whatever format you deliver it (I would suggest either DPX sequence, uncompressed Quicktime, or Prores4444, with 5.1 audio either embedded or separate), but with the knowledge that it is in video space - and make a DCP that projects on a standard DCI compliant projector and looks virtually identical to your video product on a properly calibrated video monitor. How they do that should be irrelevant to you. "Do it yourself" only works if you really know what it is you're doing, have the equipment to do it and test it properly, and want to take on the responsibility of it being compatible with the intended distribution venues. If you are hiring a company to do that for you, you should not be doing anything to alter what you know how to make properly, because in doing so you are essentially taking on responsibility that should be theirs. If they don't see it that way, you might want to look elsewhere.


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Juan Salvo
Re: DCP looked lifted
on Feb 22, 2014 at 11:14:49 pm

Of course all that requires proper 709 viewing and pipeline, with a calibrated display and a high degree of confidence. Otherwise even the most experienced DCP author won't be able to make your film look right, cause it's been graded under whatever conditions it might have been. GIGO.

http://JuanSalvo.com
http://theColourSpace.com


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Margus Voll
Re: DCP looked lifted
on Feb 23, 2014 at 8:27:59 am

Proper DCP houses take your 709 video level files and deliver proper DCP.

Your display chain should be correct and then i see no problems.

We do it here on daily basis with Clipster or with software and the results are accurate.

--

Margus

http://iconstudios.eu
https://vimeo.com/iconstudioseu/videos

DaVinci 10, OSX 10.8.5
MacPro 5.1 2x2,93 24GB
GUI 4000 / GPU GTX 780
DL 4K
Eizo Color
Scope Box
Full Ligthspace CMS


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Ernest Savage
Re: DCP looked lifted
on Feb 27, 2014 at 5:53:45 am

Thanks for the confirmation. Several people have chimed in and all agree. Work in Rec 709 video levels (64-940) and let DCP house make the conversion. They say there will be about a 4% difference in contrast and chroma. Hopefully it's not enough for a regrade.


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