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DCP looked lifted
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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15 Replies
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easyDCP does not make the colour conversion by itself?
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Margus
https://iconstudios.eu
https://vimeo.com/iconstudioseu/videosDaVinci 9, OSX 10.7.4
MacPro 5.1 2×2,93 24GB
GTX 470 / Quadro 4000
Multibridge 2 Pro -
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 -
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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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
https://iconstudios.eu
https://vimeo.com/iconstudioseu/videosDaVinci 9, OSX 10.7.4
MacPro 5.1 2×2,93 24GB
GTX 470 / Quadro 4000
Multibridge 2 Pro -
Have you tried to ProRes(HQ) in DATA level? It might work…
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The easyDCP manual says it does this:
Is that doing more than the rec709toXYZ LUT in Resolve?
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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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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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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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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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